Merge remote-tracking branch 'rcu/rcu/next'
authorStephen Rothwell <sfr@canb.auug.org.au>
Tue, 13 Sep 2016 02:12:37 +0000 (12:12 +1000)
committerStephen Rothwell <sfr@canb.auug.org.au>
Tue, 13 Sep 2016 02:12:37 +0000 (12:12 +1000)
47 files changed:
Documentation/RCU/Design/Expedited-Grace-Periods/ExpRCUFlow.svg [new file with mode: 0644]
Documentation/RCU/Design/Expedited-Grace-Periods/ExpSchedFlow.svg [new file with mode: 0644]
Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.html [new file with mode: 0644]
Documentation/RCU/Design/Expedited-Grace-Periods/Funnel0.svg [new file with mode: 0644]
Documentation/RCU/Design/Expedited-Grace-Periods/Funnel1.svg [new file with mode: 0644]
Documentation/RCU/Design/Expedited-Grace-Periods/Funnel2.svg [new file with mode: 0644]
Documentation/RCU/Design/Expedited-Grace-Periods/Funnel3.svg [new file with mode: 0644]
Documentation/RCU/Design/Expedited-Grace-Periods/Funnel4.svg [new file with mode: 0644]
Documentation/RCU/Design/Expedited-Grace-Periods/Funnel5.svg [new file with mode: 0644]
Documentation/RCU/Design/Expedited-Grace-Periods/Funnel6.svg [new file with mode: 0644]
Documentation/RCU/Design/Expedited-Grace-Periods/Funnel7.svg [new file with mode: 0644]
Documentation/RCU/Design/Expedited-Grace-Periods/Funnel8.svg [new file with mode: 0644]
Documentation/RCU/Design/Requirements/Requirements.html
Documentation/RCU/torture.txt
drivers/misc/lkdtm.h
drivers/misc/lkdtm_bugs.c
drivers/misc/lkdtm_core.c
include/linux/bug.h
include/linux/list.h
include/linux/rculist.h
include/linux/rcupdate.h
include/linux/torture.h
kernel/cpu.c
kernel/rcu/Makefile
kernel/rcu/rcuperf.c
kernel/rcu/rcutorture.c
kernel/rcu/tree.c
kernel/rcu/tree.h
kernel/rcu/tree_exp.h
kernel/rcu/tree_plugin.h
kernel/rcu/tree_trace.c
kernel/rcu/update.c
kernel/rcu/waketorture.c [new file with mode: 0644]
kernel/sched/core.c
kernel/torture.c
lib/Kconfig.debug
lib/list_debug.c
tools/testing/selftests/rcutorture/bin/kvm-recheck-wake.sh [new file with mode: 0755]
tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
tools/testing/selftests/rcutorture/bin/kvm.sh
tools/testing/selftests/rcutorture/configs/wake/CFLIST [new file with mode: 0644]
tools/testing/selftests/rcutorture/configs/wake/CFcommon [new file with mode: 0644]
tools/testing/selftests/rcutorture/configs/wake/SH [new file with mode: 0644]
tools/testing/selftests/rcutorture/configs/wake/SH.boot [new file with mode: 0644]
tools/testing/selftests/rcutorture/configs/wake/STI [new file with mode: 0644]
tools/testing/selftests/rcutorture/configs/wake/STI.boot [new file with mode: 0644]
tools/testing/selftests/rcutorture/configs/wake/ver_functions.sh [new file with mode: 0644]

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+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
+        "http://www.w3.org/TR/html4/loose.dtd">
+        <html>
+        <head><title>A Tour Through TREE_RCU's Expedited Grace Periods</title>
+        <meta HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
+
+<h2>Introduction</h2>
+
+This document describes RCU's expedited grace periods.
+Unlike RCU's normal grace periods, which accept long latencies to attain
+high efficiency and minimal disturbance, expedited grace periods accept
+lower efficiency and significant disturbance to attain shorter latencies.
+
+<p>
+There are three flavors of RCU (RCU-bh, RCU-preempt, and RCU-sched),
+but only two flavors of expedited grace periods because the RCU-bh
+expedited grace period maps onto the RCU-sched expedited grace period.
+Each of the remaining two implementations is covered in its own section.
+
+<ol>
+<li>   <a href="#Expedited Grace Period Design">
+       Expedited Grace Period Design</a>
+<li>   <a href="#RCU-preempt Expedited Grace Periods">
+       RCU-preempt Expedited Grace Periods</a>
+<li>   <a href="#RCU-sched Expedited Grace Periods">
+       RCU-sched Expedited Grace Periods</a>
+<li>   <a href="#Expedited Grace Period and CPU Hotplug">
+       Expedited Grace Period and CPU Hotplug</a>
+<li>   <a href="#Expedited Grace Period Refinements">
+       Expedited Grace Period Refinements</a>
+</ol>
+
+At the end we have the inescapable
+<a href="#Answers to Quick Quizzes">answers to the quick quizzes</a>.
+
+<h2><a name="Expedited Grace Period Design">
+Expedited Grace Period Design</a></h2>
+
+<p>
+The expedited RCU grace periods cannot be accused of being subtle,
+given that they for all intents and purposes hammer every CPU that
+has not yet provided a quiescent state for the current expedited
+grace period.
+The one saving grace is that the hammer has grown a bit smaller
+over time:  The old call to <tt>try_stop_cpus()</tt> has been
+replaced with a set of calls to <tt>smp_call_function_single()</tt>,
+each of which results in an IPI to the target CPU.
+The corresponding handler function checks the CPU's state, motivating
+a faster quiescent state where possible, and triggering a report
+of that quiescent state.
+As always for RCU, once everything has spent some time in a quiescent
+state, the expedited grace period has completed.
+
+<p>
+The details of the <tt>smp_call_function_single()</tt> handler's
+operation depend on the RCU flavor, as described in the following
+sections.
+
+<h2><a name="RCU-preempt Expedited Grace Periods">
+RCU-preempt Expedited Grace Periods</a></h2>
+
+<p>
+The overall flow of the handling of a given CPU by an RCU-preempt
+expedited grace period is shown in the following diagram:
+
+<p><img src="ExpRCUFlow.svg" alt="ExpRCUFlow.svg" width="55%">
+
+<p>
+The solid arrows denote direct action, for example, a function call.
+The dotted arrows denote indirect action, for example, an IPI
+or a state that is reached after some time.
+
+<p>
+If a given CPU is offline or idle, <tt>synchronize_rcu_expedited()</tt>
+will ignore it because idle and offline CPUs are already residing
+in quiescent states.
+Otherwise, the expedited grace period will use
+<tt>smp_call_function_single()</tt> to send the CPU an IPI, which
+is handled by <tt>sync_rcu_exp_handler()</tt>.
+
+<p>
+However, because this is preemptible RCU, <tt>sync_rcu_exp_handler()</tt>
+can check to see if the CPU is currently running in an RCU read-side
+critical section.
+If not, the handler can immediately report a quiescent state.
+Otherwise, it sets flags so that the outermost <tt>rcu_read_unlock()</tt>
+invocation will provide the needed quiescent-state report.
+This flag-setting avoids the previous forced preemption of all
+CPUs that might have RCU read-side critical sections.
+In addition, this flag-setting is done so as to avoid increasing
+the overhead of the common-case fastpath through the scheduler.
+
+<p>
+Again because this is preemptible RCU, an RCU read-side critical section
+can be preempted.
+When that happens, RCU will enqueue the task, which will the continue to
+block the current expedited grace period until it resumes and finds its
+outermost <tt>rcu_read_unlock()</tt>.
+The CPU will report a quiescent state just after enqueuing the task because
+the CPU is no longer blocking the grace period.
+It is instead the preempted task doing the blocking.
+
+<table>
+<tr><th>&nbsp;</th></tr>
+<tr><th align="left">Quick Quiz:</th></tr>
+<tr><td>
+       Why not just have the expedited grace period check the
+       state of all the CPUs?
+       After all, that would avoid all those real-time-unfriendly IPIs.
+</td></tr>
+<tr><th align="left">Answer:</th></tr>
+<tr><td bgcolor="#ffffff"><font color="ffffff">
+       Because we want the RCU read-side critical sections to run fast,
+       which means no memory barriers.
+       Therefore, it is not possible to safely check the state from some
+       other CPU.
+       And even if it was possible to safely check the state, it would
+       still be necessary to IPI the CPU to safely interact with the
+       upcoming <tt>rcu_read_unlock()</tt> invocation, which means that
+       the remote state testing would not help the worst-case
+       latency that real-time applications care about.
+
+       <p><font color="ffffff">One way to prevent your real-time
+       application from getting hit with these IPIs is to
+       build your kernel with <tt>CONFIG_NO_HZ_FULL=y</tt>.
+       RCU would then perceive the CPU running your application
+       as being idle, and it would be able to safely detect that
+       state without needing to IPI the CPU.
+</font></td></tr>
+<tr><td>&nbsp;</td></tr>
+</table>
+
+<p>
+Please note that this is just the overall flow:
+Additional complications can arise due to races with CPUs going idle
+or offline, among other things.
+
+<h2><a name="RCU-sched Expedited Grace Periods">
+RCU-sched Expedited Grace Periods</a></h2>
+
+<p>
+The overall flow of the handling of a given CPU by an RCU-sched
+expedited grace period is shown in the following diagram:
+
+<p><img src="ExpSchedFlow.svg" alt="ExpSchedFlow.svg" width="55%">
+
+<p>
+As with RCU-preempt's <tt>synchronize_rcu_expedited()</tt>,
+<tt>synchronize_sched_expedited()</tt> ignores offline and
+idle CPUs, again because they are in remotely detectable
+quiescent states.
+However, the <tt>synchronize_rcu_expedited()</tt> handler
+is <tt>sync_sched_exp_handler()</tt>, and because the
+<tt>rcu_read_lock_sched()</tt> and <tt>rcu_read_unlock_sched()</tt>
+leave no trace of their invocation, in general it is not possible to tell
+whether or not the current CPU is in an RCU read-side critical section.
+The best that <tt>sync_sched_exp_handler()</tt> can do is to check
+for idle, on the off-chance that the CPU went idle while the IPI
+was in flight.
+If the CPU is idle, then tt>sync_sched_exp_handler()</tt> reports
+the quiescent state.
+
+<p>
+Otherwise, the handler invokes <tt>resched_cpu()</tt>, which forces
+a future context switch.
+At the time of the context switch, the CPU reports the quiescent state.
+Should the CPU go offline first, it will report the quiescent state
+at that time.
+
+<h2><a name="Expedited Grace Period and CPU Hotplug">
+Expedited Grace Period and CPU Hotplug</a></h2>
+
+<p>
+The expedited nature of expedited grace periods require a much tighter
+interaction with CPU hotplug operations than is required for normal
+grace periods.
+In addition, attempting to IPI offline CPUs will result in splats, but
+failing to IPI online CPUs can result in too-short grace periods.
+Neither option is acceptable in production kernels.
+
+<p>
+The interaction between expedited grace periods and CPU hotplug operations
+is carried out at several levels:
+
+<ol>
+<li>   The number of CPUs that have ever been online is tracked
+       by the <tt>rcu_state</tt> structure's <tt>-&gt;ncpus</tt>
+       field.
+       The <tt>rcu_state</tt> structure's <tt>-&gt;ncpus_snap</tt>
+       field tracks the number of CPUs that have ever been online
+       at the beginning of an RCU expedited grace period.
+<li>   The identities of the CPUs that have ever been online is
+       tracked by the <tt>rcu_node</tt> structure's
+       <tt>-&gt;expmaskinitnext</tt> field.
+       The <tt>rcu_node</tt> structure's <tt>-&gt;expmaskinit</tt>
+       field tracks the identities of the CPUs that were online
+       at least once at the beginning of the most recent RCU
+       expedited grace period.
+       The <tt>rcu_state</tt> structure's <tt>-&gt;ncpus</tt> and
+       <tt>-&gt;ncpus_snap</tt> fields are used to detect when
+       new CPUs have come online for the first time, that is,
+       when the <tt>rcu_node</tt> structure's <tt>-&gt;expmaskinitnext</tt>
+       field has changed since the beginning of the last RCU
+       expedited grace period, which triggers an update of each
+       <tt>rcu_node</tt> structure's <tt>-&gt;expmaskinit</tt>
+       field from its <tt>-&gt;expmaskinitnext</tt> field.
+<li>   Each <tt>rcu_node</tt> structure's <tt>-&gt;expmaskinit</tt>
+       field is used to initialize that structure's
+       <tt>-&gt;expmask</tt> at the beginning of each RCU
+       expedited grace period.
+       This means that only those CPUs that have been online at least
+       once will be considered for a given grace period.
+<li>   Any CPU that goes offline will clear its bit in its leaf
+       <tt>rcu_node</tt> structure's <tt>-&gt;qsmaskinitnext</tt>
+       field, so any CPU with that bit clear can safely be ignored.
+       However, it is possible for a CPU coming online or going offline
+       to have this bit set for some time while <tt>cpu_online</tt>
+       returns <tt>false</tt>.
+<li>   For each non-idle CPU that RCU believes is currently online, the grace
+       period invokes <tt>smp_call_function_single()</tt>.
+       If this succeeds, the CPU was fully online.
+       Failure indicates that the CPU is in the process of coming online
+       or going offline, in which case it is necessary to wait for a
+       short time period and try again.
+       a concurrent CPU-hotplug operation to complete.
+<li>   In the case of RCU-sched, one of the last acts of an outgoing CPU
+       is to invoke <tt>rcu_report_dead()</tt>, which
+       reports a quiescent state for that CPU.
+       However, this is likely paranoia-induced redundancy. <!-- @@@ -->
+</ol>
+
+<table>
+<tr><th>&nbsp;</th></tr>
+<tr><th align="left">Quick Quiz:</th></tr>
+<tr><td>
+       Why all the dancing around with multiple counters and masks
+       tracking CPUs that were once online?
+       Why not just have a single set of masks tracking the currently
+       online CPUs and be done with it?
+</td></tr>
+<tr><th align="left">Answer:</th></tr>
+<tr><td bgcolor="#ffffff"><font color="ffffff">
+       Maintaining single set of masks tracking the online CPUs <i>sounds</i>
+       easier, at least until you try working out all the race conditions
+       between grace-period initialization and CPU-hotplug operations.
+       For example, suppose initialization is progressing down the
+       tree while a CPU-offline operation is progressing up the tree.
+       This situation can result in bits set at the top of the tree
+       that have no counterparts at the bottom of the tree.
+       Those bits will never be cleared, which will result in
+       grace-period hangs.
+       In short, that way lies madness, to say nothing of a great many
+       bugs, hangs, and deadlocks.
+
+       <p><font color="ffffff">
+       In contrast, the current multi-mask multi-counter scheme ensures
+       that grace-period initialization will always see consistent masks
+       up and down the tree, which brings significant simplifications
+       over the single-mask method.
+</font></td></tr>
+<tr><td>&nbsp;</td></tr>
+</table>
+
+<h2><a name="Expedited Grace Period Refinements">
+Expedited Grace Period Refinements</a></h2>
+
+<ol>
+<li>   <a href="#Idle-CPU Checks">Idle-CPU checks</a>.
+<li>   <a href="#Batching via Sequence Counter">
+       Batching via sequence counter</a>.
+<li>   <a href="#Funnel Locking and Wait/Wakeup">
+       Funnel locking and wait/wakeup</a>.
+<li>   <a href="#Use of Workqueues">Use of Workqueues</a>.
+<li>   <a href="#Stall Warnings">Stall warnings</a>.
+</ol>
+
+<h3><a name="Idle-CPU Checks">Idle-CPU Checks</a></h3>
+
+<p>@@@
+
+<h3><a name="Batching via Sequence Counter">
+Batching via Sequence Counter</a></h3>
+
+<p>
+If each grace-period request was carried out separately, expedited
+grace periods would have abysmal scalability and high-load characteristics.
+Because each grace-period operation can serve an unlimited number of
+updates, it is important to <i>batch</i> requests, so that a single
+expedited grace-period operation will cover all requests in the
+corresponding batch.
+
+<p>
+This batching is controlled by a sequence counter named
+<tt>-&gt;expedited_sequence</tt> in the <tt>rcu_state</tt> structure.
+This counter has an odd value when there is an expedited grace period
+in progress and an even value otherwise, so that dividing the counter
+value by two gives the number of completed grace periods.
+During any given update request, the counter must transition from
+even to odd and then back to even, thus indicating that a grace
+period has elapsed.
+Therefore, if the initial value of the counter is <tt>s</tt>,
+the updater must wait until the counter reaches at least the
+value <tt>(s+3)&amp;~0x1</tt>.
+
+<p>
+Again, only one request in a given batch need actually carry out
+a grace-period operation, which means that the rest need some way
+to efficiently wait for that grace period to complete.
+However, that is the topic of the next section.
+
+<h3><a name="Funnel Locking and Wait/Wakeup">
+Funnel Locking and Wait/Wakeup</a></h3>
+
+<p>
+The natural way to sort out which of a batch of updaters will initiate
+the expedited grace period is to use the <tt>rcu_node</tt> combining
+tree.
+The first updater corresponding to a given grace period arriving
+at a given <tt>rcu_node</tt> structure records its desired grace-period
+sequence number in the <tt>-&gt;exp_seq_rq</tt> field and move up
+to the next level in the tree.
+Otherwise, if the <tt>-&gt;exp_seq_rq</tt> field already contains
+the sequence number for the desire grace period or some later one,
+the updater blocks on one of four wait queues in the
+<tt>-&gt;exp_wq[]</tt> array, using the second-from-bottom
+and third-from bottom bits as an index.
+An <tt>-&gt;exp_lock</tt> field in the <tt>rcu_node</tt> structure
+synchronizes access to these fields.
+
+<p>
+An empty <tt>rcu_node</tt> tree is shown in the following diagram,
+with the white cells representing the <tt>-&gt;exp_seq_rq</tt> field
+and the red cells representing the elements of the
+<tt>-&gt;exp_wq[]</tt> array.
+
+<p><img src="Funnel0.svg" alt="Funnel0.svg" width="75%">
+
+<p>
+The next diagram shows the situation after the arrival of Task&nbsp;A
+and Task&nbsp;B at the leftmost and rightmost leaf <tt>rcu_node</tt>
+structures, respectively.
+The current value of the <tt>rcu_state</tt> structure's
+<tt>-&gt;expedited_sequence</tt> field is zero, so adding three and
+clearing the bottom bit results in the value two, which both tasks
+record in the <tt>-&gt;exp_seq_rq</tt> field of their respective
+<tt>rcu_node</tt> structures:
+
+<p><img src="Funnel1.svg" alt="Funnel1.svg" width="75%">
+
+<p>
+Each of Tasks&nbsp;A and&nbsp;B will move up to the root
+<tt>rcu_node</tt> structure.
+Suppose that Task&nbsp;A wins, recording its desired grace-period sequence
+number and resulting in the state shown below:
+
+<p><img src="Funnel2.svg" alt="Funnel2.svg" width="75%">
+
+<p>
+Task&nbsp;A now advances to initiate a new grace period, while Task&nbsp;B
+moves up to the root <tt>rcu_node</tt> structure, and, seeing that
+its desired sequence number is already recorded, blocks on
+<tt>-&gt;exp_wq[1]</tt>.
+
+<table>
+<tr><th>&nbsp;</th></tr>
+<tr><th align="left">Quick Quiz:</th></tr>
+<tr><td>
+       Why <tt>-&gt;exp_wq[1]</tt>?
+       Given that the value of these tasks' desired sequence number is
+       two, so shouldn't they instead block on <tt>-&gt;exp_wq[2]</tt>?
+</td></tr>
+<tr><th align="left">Answer:</th></tr>
+<tr><td bgcolor="#ffffff"><font color="ffffff">
+       No.
+
+       <p><font color="ffffff">
+       Recall that the bottom bit of the desired sequence number indicates
+       whether or not a grace period is currently in progress.
+       It is therefore necessary to shift the sequence number right one
+       bit position to obtain the number of the grace period.
+       This results in <tt>-&gt;exp_wq[1]</tt>.
+</font></td></tr>
+<tr><td>&nbsp;</td></tr>
+</table>
+
+<p>
+If Tasks&nbsp;C and&nbsp;D also arrive at this point, they will compute the
+same desired grace-period sequence number, and see that both leaf
+<tt>rcu_node</tt> structures already have that value recorded.
+They will therefore block on their respective <tt>rcu_node</tt>
+structures' <tt>-&gt;exp_wq[1]</tt> fields, as shown below:
+
+<p><img src="Funnel3.svg" alt="Funnel3.svg" width="75%">
+
+<p>
+Task&nbsp;A now acquires the <tt>rcu_state</tt> structure's
+<tt>-&gt;exp_mutex</tt> and initiates the grace period, which
+increments <tt>-&gt;expedited_sequence</tt>.
+Therefore, if Tasks&nbsp;E and&nbsp;F arrive, they will compute
+a desired sequence number of 4 and will record this value as
+shown below:
+
+<p><img src="Funnel4.svg" alt="Funnel4.svg" width="75%">
+
+<p>
+Tasks&nbsp;E and&nbsp;F will propagate up the <tt>rcu_node</tt>
+combining tree, with Task&nbsp;F blocking on the root <tt>rcu_node</tt>
+structure and Task&nbsp;E wait for Task&nbsp;A to finish so that
+it can start the next grace period.
+The resulting state is as shown below:
+
+<p><img src="Funnel5.svg" alt="Funnel5.svg" width="75%">
+
+<p>
+Once the grace period completes, Task&nbsp;A
+starts waking up the tasks waiting for this grace period to complete,
+increments the <tt>-&gt;expedited_sequence</tt>,
+acquires the <tt>-&gt;exp_wake_mutex</tt> and then releases the
+<tt>-&gt;exp_mutex</tt>.
+This results in the following state:
+
+<p><img src="Funnel6.svg" alt="Funnel6.svg" width="75%">
+
+<p>
+Task&nbsp;E can then acquire <tt>-&gt;exp_mutex</tt> and increment
+<tt>-&gt;expedited_sequence</tt> to the value three.
+If new tasks&nbsp;G and&nbsp;H arrive and moves up the combining tree at the
+same time, the state will be as follows:
+
+<p><img src="Funnel7.svg" alt="Funnel7.svg" width="75%">
+
+<p>
+Note that three of the root <tt>rcu_node</tt> structure's
+waitqueues are now occupied.
+However, at some point, Task&nbsp;A will wake up the
+tasks blocked on the <tt>-&gt;exp_wq</tt> waitqueues, resulting
+in the following state:
+
+<p><img src="Funnel8.svg" alt="Funnel8.svg" width="75%">
+
+<p>
+Execution will continue with Tasks&nbsp;E and&nbsp;H completing
+their grace periods and carrying out their wakeups.
+
+<table>
+<tr><th>&nbsp;</th></tr>
+<tr><th align="left">Quick Quiz:</th></tr>
+<tr><td>
+       What happens if Task&nbsp;A takes so long to do its wakeups
+       that Task&nbsp;E's grace period completes?
+</td></tr>
+<tr><th align="left">Answer:</th></tr>
+<tr><td bgcolor="#ffffff"><font color="ffffff">
+       Then Task&nbsp;E will block on the <tt>-&gt;exp_wake_mutex</tt>,
+       which will also prevent it from releasing <tt>-gt;exp_mutex</tt>,
+       which in turn will prevent the next grace period from starting.
+       This last is important in preventing overflow of the
+       <tt>-&gt;exp_wq[]</tt> array.
+</font></td></tr>
+<tr><td>&nbsp;</td></tr>
+</table>
+
+<h3><a name="Use of Workqueues">Use of Workqueues</a></h3>
+
+<h3><a name="Stall Warnings">Stall Warnings</a></h3>
+
+<p>@@@
+
+Includes overlapping wakeup phase with next expedited grace period.
+
+<h3><a name="Summary">
+Summary</a></h3>
+
+<p>@@@
+
+</body></html>
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index ece410f40436dc4f88fdf521bf84b7191b0ff798..a4d3838130e4ef6c30ac7ece5dc56e452d5274cb 100644 (file)
@@ -2493,6 +2493,28 @@ or some future &ldquo;lazy&rdquo;
 variant of <tt>call_rcu()</tt> that might one day be created for
 energy-efficiency purposes.
 
+<p>
+That said, there are limits.
+RCU requires that the <tt>rcu_head</tt> structure be aligned to a
+two-byte boundary, and passing a misaligned <tt>rcu_head</tt>
+structure to one of the <tt>call_rcu()</tt> family of functions
+will result in a splat.
+It is therefore necessary to exercise caution when packing
+structures containing fields of type <tt>rcu_head</tt>.
+Why not a four-byte or even eight-byte alignment requirement?
+Because the m68k architecture provides only two-byte alignment,
+and thus acts as alignment's least common denominator.
+
+<p>
+The reason for reserving the bottom bit of pointers to
+<tt>rcu_head</tt> structures is to leave the door open to
+&ldquo;lazy&rdquo; callbacks whose invocations can safely be deferred.
+Deferring invocation could potentially have energy-efficiency
+benefits, but only if the rate of non-lazy callbacks decreases
+significantly for some important workload.
+In the meantime, reserving the bottom bit keeps this option open
+in case it one day becomes useful.
+
 <h3><a name="Performance, Scalability, Response Time, and Reliability">
 Performance, Scalability, Response Time, and Reliability</a></h3>
 
index 118e7c176ce76aaca534c50fe7fe01da1cb3b710..278f6a9383b6c29c4714b97e9d51058984bd2711 100644 (file)
@@ -10,21 +10,6 @@ status messages via printk(), which can be examined via the dmesg
 command (perhaps grepping for "torture").  The test is started
 when the module is loaded, and stops when the module is unloaded.
 
-CONFIG_RCU_TORTURE_TEST_RUNNABLE
-
-It is also possible to specify CONFIG_RCU_TORTURE_TEST=y, which will
-result in the tests being loaded into the base kernel.  In this case,
-the CONFIG_RCU_TORTURE_TEST_RUNNABLE config option is used to specify
-whether the RCU torture tests are to be started immediately during
-boot or whether the /proc/sys/kernel/rcutorture_runnable file is used
-to enable them.  This /proc file can be used to repeatedly pause and
-restart the tests, regardless of the initial state specified by the
-CONFIG_RCU_TORTURE_TEST_RUNNABLE config option.
-
-You will normally -not- want to start the RCU torture tests during boot
-(and thus the default is CONFIG_RCU_TORTURE_TEST_RUNNABLE=n), but doing
-this can sometimes be useful in finding boot-time bugs.
-
 
 MODULE PARAMETERS
 
index fdf954c2107f935a36ca719ee6cd760a3d6e9182..cfa1039c62e725289cfe74aebb7a36de92b22eb2 100644 (file)
@@ -21,6 +21,8 @@ void lkdtm_SPINLOCKUP(void);
 void lkdtm_HUNG_TASK(void);
 void lkdtm_ATOMIC_UNDERFLOW(void);
 void lkdtm_ATOMIC_OVERFLOW(void);
+void lkdtm_CORRUPT_LIST_ADD(void);
+void lkdtm_CORRUPT_LIST_DEL(void);
 
 /* lkdtm_heap.c */
 void lkdtm_OVERWRITE_ALLOCATION(void);
index 182ae1894b328861323c42767aadd5f2588318b9..f336206d4b1ff74b6a45cd50e3b77bd1b5bd8c3f 100644 (file)
@@ -5,8 +5,13 @@
  * test source files.
  */
 #include "lkdtm.h"
+#include <linux/list.h>
 #include <linux/sched.h>
 
+struct lkdtm_list {
+       struct list_head node;
+};
+
 /*
  * Make sure our attempts to over run the kernel stack doesn't trigger
  * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
@@ -146,3 +151,66 @@ void lkdtm_ATOMIC_OVERFLOW(void)
        pr_info("attempting bad atomic overflow\n");
        atomic_inc(&over);
 }
+
+void lkdtm_CORRUPT_LIST_ADD(void)
+{
+       /*
+        * Initially, an empty list via LIST_HEAD:
+        *      test_head.next = &test_head
+        *      test_head.prev = &test_head
+        */
+       LIST_HEAD(test_head);
+       struct lkdtm_list good, bad;
+       void *target[2] = { };
+       void *redirection = &target;
+
+       pr_info("attempting good list addition\n");
+
+       /*
+        * Adding to the list performs these actions:
+        *      test_head.next->prev = &good.node
+        *      good.node.next = test_head.next
+        *      good.node.prev = test_head
+        *      test_head.next = good.node
+        */
+       list_add(&good.node, &test_head);
+
+       pr_info("attempting corrupted list addition\n");
+       /*
+        * In simulating this "write what where" primitive, the "what" is
+        * the address of &bad.node, and the "where" is the address held
+        * by "redirection".
+        */
+       test_head.next = redirection;
+       list_add(&bad.node, &test_head);
+
+       if (target[0] == NULL && target[1] == NULL)
+               pr_err("Overwrite did not happen, but no BUG?!\n");
+       else
+               pr_err("list_add() corruption not detected!\n");
+}
+
+void lkdtm_CORRUPT_LIST_DEL(void)
+{
+       LIST_HEAD(test_head);
+       struct lkdtm_list item;
+       void *target[2] = { };
+       void *redirection = &target;
+
+       list_add(&item.node, &test_head);
+
+       pr_info("attempting good list removal\n");
+       list_del(&item.node);
+
+       pr_info("attempting corrupted list removal\n");
+       list_add(&item.node, &test_head);
+
+       /* As with the list_add() test above, this corrupts "next". */
+       item.node.next = redirection;
+       list_del(&item.node);
+
+       if (target[0] == NULL && target[1] == NULL)
+               pr_err("Overwrite did not happen, but no BUG?!\n");
+       else
+               pr_err("list_del() corruption not detected!\n");
+}
index f9154b8d67f6974bd6a7f27c24be9e6b0b985ebe..7eeb71a755499f94cb576902200472145c331e25 100644 (file)
@@ -197,6 +197,8 @@ struct crashtype crashtypes[] = {
        CRASHTYPE(EXCEPTION),
        CRASHTYPE(LOOP),
        CRASHTYPE(OVERFLOW),
+       CRASHTYPE(CORRUPT_LIST_ADD),
+       CRASHTYPE(CORRUPT_LIST_DEL),
        CRASHTYPE(CORRUPT_STACK),
        CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
        CRASHTYPE(OVERWRITE_ALLOCATION),
index 292d6a10b0c2683ecbd57858ca069e3dc0bb952e..baff2e8fc8a82792045c3bb0112fb52cead7e6cb 100644 (file)
@@ -121,4 +121,21 @@ static inline enum bug_trap_type report_bug(unsigned long bug_addr,
 }
 
 #endif /* CONFIG_GENERIC_BUG */
+
+/*
+ * Since detected data corruption should stop operation on the affected
+ * structures, this returns false if the corruption condition is found.
+ */
+#define CHECK_DATA_CORRUPTION(condition, fmt, ...)                      \
+       do {                                                             \
+               if (unlikely(condition)) {                               \
+                       if (IS_ENABLED(CONFIG_BUG_ON_DATA_CORRUPTION)) { \
+                               pr_err(fmt, ##__VA_ARGS__);              \
+                               BUG();                                   \
+                       } else                                           \
+                               WARN(1, fmt, ##__VA_ARGS__);             \
+                       return false;                                    \
+               }                                                        \
+       } while (0)
+
 #endif /* _LINUX_BUG_H */
index 5183138aa932da88c83177b9f8372bd9c3437e13..d1039ecaf94fdbea21a25c0fa4a5ea351683dd91 100644 (file)
@@ -28,27 +28,42 @@ static inline void INIT_LIST_HEAD(struct list_head *list)
        list->prev = list;
 }
 
+#ifdef CONFIG_DEBUG_LIST
+extern bool __list_add_valid(struct list_head *new,
+                             struct list_head *prev,
+                             struct list_head *next);
+extern bool __list_del_entry_valid(struct list_head *entry);
+#else
+static inline bool __list_add_valid(struct list_head *new,
+                               struct list_head *prev,
+                               struct list_head *next)
+{
+       return true;
+}
+static inline bool __list_del_entry_valid(struct list_head *entry)
+{
+       return true;
+}
+#endif
+
 /*
  * Insert a new entry between two known consecutive entries.
  *
  * This is only for internal list manipulation where we know
  * the prev/next entries already!
  */
-#ifndef CONFIG_DEBUG_LIST
 static inline void __list_add(struct list_head *new,
                              struct list_head *prev,
                              struct list_head *next)
 {
+       if (!__list_add_valid(new, prev, next))
+               return;
+
        next->prev = new;
        new->next = next;
        new->prev = prev;
        WRITE_ONCE(prev->next, new);
 }
-#else
-extern void __list_add(struct list_head *new,
-                             struct list_head *prev,
-                             struct list_head *next);
-#endif
 
 /**
  * list_add - add a new entry
@@ -96,22 +111,20 @@ static inline void __list_del(struct list_head * prev, struct list_head * next)
  * Note: list_empty() on entry does not return true after this, the entry is
  * in an undefined state.
  */
-#ifndef CONFIG_DEBUG_LIST
 static inline void __list_del_entry(struct list_head *entry)
 {
+       if (!__list_del_entry_valid(entry))
+               return;
+
        __list_del(entry->prev, entry->next);
 }
 
 static inline void list_del(struct list_head *entry)
 {
-       __list_del(entry->prev, entry->next);
+       __list_del_entry(entry);
        entry->next = LIST_POISON1;
        entry->prev = LIST_POISON2;
 }
-#else
-extern void __list_del_entry(struct list_head *entry);
-extern void list_del(struct list_head *entry);
-#endif
 
 /**
  * list_replace - replace old entry by new one
@@ -381,8 +394,11 @@ static inline void list_splice_tail_init(struct list_head *list,
  *
  * Note that if the list is empty, it returns NULL.
  */
-#define list_first_entry_or_null(ptr, type, member) \
-       (!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
+#define list_first_entry_or_null(ptr, type, member) ({ \
+       struct list_head *head__ = (ptr); \
+       struct list_head *pos__ = READ_ONCE(head__->next); \
+       pos__ != head__ ? list_entry(pos__, type, member) : NULL; \
+})
 
 /**
  * list_next_entry - get the next element in list
index 8beb98dcf14f066fc4e9075ed0b94cc29998c9bc..4f7a9561b8c415d069505dab632b922903d87d2e 100644 (file)
@@ -45,19 +45,17 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list)
  * This is only for internal list manipulation where we know
  * the prev/next entries already!
  */
-#ifndef CONFIG_DEBUG_LIST
 static inline void __list_add_rcu(struct list_head *new,
                struct list_head *prev, struct list_head *next)
 {
+       if (!__list_add_valid(new, prev, next))
+               return;
+
        new->next = next;
        new->prev = prev;
        rcu_assign_pointer(list_next_rcu(prev), new);
        next->prev = new;
 }
-#else
-void __list_add_rcu(struct list_head *new,
-                   struct list_head *prev, struct list_head *next);
-#endif
 
 /**
  * list_add_rcu - add a new entry to rcu-protected list
index 1aa62e1a761bb851acffbd947e8be7df067ab660..321f9ed552a995f396696b71343f66cbd2e01d9e 100644 (file)
@@ -334,6 +334,7 @@ void rcu_sched_qs(void);
 void rcu_bh_qs(void);
 void rcu_check_callbacks(int user);
 void rcu_report_dead(unsigned int cpu);
+void rcu_cpu_starting(unsigned int cpu);
 
 #ifndef CONFIG_TINY_RCU
 void rcu_end_inkernel_boot(void);
index 6685a73736a2ecb77ce4bbec47e85b9dc207c332..a45702eb3e7b9eb1188f8076ba5c69abc1f510ed 100644 (file)
@@ -43,7 +43,7 @@
 
 #define TORTURE_FLAG "-torture:"
 #define TOROUT_STRING(s) \
-       pr_alert("%s" TORTURE_FLAG s "\n", torture_type)
+       pr_alert("%s" TORTURE_FLAG " %s\n", torture_type, s)
 #define VERBOSE_TOROUT_STRING(s) \
        do { if (verbose) pr_alert("%s" TORTURE_FLAG " %s\n", torture_type, s); } while (0)
 #define VERBOSE_TOROUT_ERRSTRING(s) \
index e7eca02c757f7ede7743cabb00aa64c787e90e7a..5df20d6d152071b40244fb5d85279b8040a641ba 100644 (file)
@@ -966,6 +966,7 @@ void notify_cpu_starting(unsigned int cpu)
        struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
        enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
 
+       rcu_cpu_starting(cpu);  /* Enables RCU usage on this CPU. */
        while (st->state < target) {
                st->state++;
                cpuhp_invoke_callback(cpu, st->state, true, NULL);
index 18dfc485225c3954ccf29a8743bc636f10db7d41..42cd319920b1d371696ad3d97d6f9de74f582ed4 100644 (file)
@@ -4,9 +4,10 @@ KCOV_INSTRUMENT := n
 
 obj-y += update.o sync.o
 obj-$(CONFIG_SRCU) += srcu.o
-obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
 obj-$(CONFIG_RCU_PERF_TEST) += rcuperf.o
+obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
 obj-$(CONFIG_TREE_RCU) += tree.o
 obj-$(CONFIG_PREEMPT_RCU) += tree.o
 obj-$(CONFIG_TREE_RCU_TRACE) += tree_trace.o
 obj-$(CONFIG_TINY_RCU) += tiny.o
+obj-$(CONFIG_WAKE_TORTURE_TEST) += waketorture.o
index d38ab08a3fe7eb5d92caf5b0c4d590299d912d90..123ccbd2244929ca822b30f68801d1680c62b404 100644 (file)
@@ -52,7 +52,7 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>");
 
 #define PERF_FLAG "-perf:"
 #define PERFOUT_STRING(s) \
-       pr_alert("%s" PERF_FLAG s "\n", perf_type)
+       pr_alert("%s" PERF_FLAG " %s\n", perf_type, s)
 #define VERBOSE_PERFOUT_STRING(s) \
        do { if (verbose) pr_alert("%s" PERF_FLAG " %s\n", perf_type, s); } while (0)
 #define VERBOSE_PERFOUT_ERRSTRING(s) \
@@ -400,9 +400,8 @@ rcu_perf_writer(void *arg)
                        sp.sched_priority = 0;
                        sched_setscheduler_nocheck(current,
                                                   SCHED_NORMAL, &sp);
-                       pr_alert("%s" PERF_FLAG
-                                "rcu_perf_writer %ld has %d measurements\n",
-                                perf_type, me, MIN_MEAS);
+                       pr_alert("%s%s rcu_perf_writer %ld has %d measurements\n",
+                                perf_type, PERF_FLAG, me, MIN_MEAS);
                        if (atomic_inc_return(&n_rcu_perf_writer_finished) >=
                            nrealwriters) {
                                schedule_timeout_interruptible(10);
index 971e2b138063a6920a96adc1f21e65619746a04b..bf08fee53dc7526a0342862976c66c40063432ed 100644 (file)
@@ -1238,6 +1238,7 @@ rcu_torture_stats_print(void)
        long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
        long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
        static unsigned long rtcv_snap = ULONG_MAX;
+       struct task_struct *wtp;
 
        for_each_possible_cpu(cpu) {
                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
@@ -1258,8 +1259,9 @@ rcu_torture_stats_print(void)
                atomic_read(&n_rcu_torture_alloc),
                atomic_read(&n_rcu_torture_alloc_fail),
                atomic_read(&n_rcu_torture_free));
-       pr_cont("rtmbe: %d rtbke: %ld rtbre: %ld ",
+       pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
                atomic_read(&n_rcu_torture_mberror),
+               n_rcu_torture_barrier_error,
                n_rcu_torture_boost_ktrerror,
                n_rcu_torture_boost_rterror);
        pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
@@ -1312,10 +1314,12 @@ rcu_torture_stats_print(void)
 
                rcutorture_get_gp_data(cur_ops->ttype,
                                       &flags, &gpnum, &completed);
-               pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x\n",
+               wtp = READ_ONCE(writer_task);
+               pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx\n",
                         rcu_torture_writer_state_getname(),
                         rcu_torture_writer_state,
-                        gpnum, completed, flags);
+                        gpnum, completed, flags,
+                        wtp == NULL ? ~0UL : wtp->state);
                show_rcu_gp_kthreads();
                rcu_ftrace_dump(DUMP_ALL);
        }
@@ -1362,12 +1366,12 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
                 onoff_interval, onoff_holdoff);
 }
 
-static void rcutorture_booster_cleanup(int cpu)
+static int rcutorture_booster_cleanup(unsigned int cpu)
 {
        struct task_struct *t;
 
        if (boost_tasks[cpu] == NULL)
-               return;
+               return 0;
        mutex_lock(&boost_mutex);
        t = boost_tasks[cpu];
        boost_tasks[cpu] = NULL;
@@ -1375,9 +1379,10 @@ static void rcutorture_booster_cleanup(int cpu)
 
        /* This must be outside of the mutex, otherwise deadlock! */
        torture_stop_kthread(rcu_torture_boost, t);
+       return 0;
 }
 
-static int rcutorture_booster_init(int cpu)
+static int rcutorture_booster_init(unsigned int cpu)
 {
        int retval;
 
@@ -1577,28 +1582,7 @@ static void rcu_torture_barrier_cleanup(void)
        }
 }
 
-static int rcutorture_cpu_notify(struct notifier_block *self,
-                                unsigned long action, void *hcpu)
-{
-       long cpu = (long)hcpu;
-
-       switch (action & ~CPU_TASKS_FROZEN) {
-       case CPU_ONLINE:
-       case CPU_DOWN_FAILED:
-               (void)rcutorture_booster_init(cpu);
-               break;
-       case CPU_DOWN_PREPARE:
-               rcutorture_booster_cleanup(cpu);
-               break;
-       default:
-               break;
-       }
-       return NOTIFY_OK;
-}
-
-static struct notifier_block rcutorture_cpu_nb = {
-       .notifier_call = rcutorture_cpu_notify,
-};
+static enum cpuhp_state rcutor_hp;
 
 static void
 rcu_torture_cleanup(void)
@@ -1638,11 +1622,8 @@ rcu_torture_cleanup(void)
        for (i = 0; i < ncbflooders; i++)
                torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
        if ((test_boost == 1 && cur_ops->can_boost) ||
-           test_boost == 2) {
-               unregister_cpu_notifier(&rcutorture_cpu_nb);
-               for_each_possible_cpu(i)
-                       rcutorture_booster_cleanup(i);
-       }
+           test_boost == 2)
+               cpuhp_remove_state(rcutor_hp);
 
        /*
         * Wait for all RCU callbacks to fire, then do flavor-specific
@@ -1869,14 +1850,13 @@ rcu_torture_init(void)
            test_boost == 2) {
 
                boost_starttime = jiffies + test_boost_interval * HZ;
-               register_cpu_notifier(&rcutorture_cpu_nb);
-               for_each_possible_cpu(i) {
-                       if (cpu_is_offline(i))
-                               continue;  /* Heuristic: CPU can go offline. */
-                       firsterr = rcutorture_booster_init(i);
-                       if (firsterr)
-                               goto unwind;
-               }
+
+               firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
+                                            rcutorture_booster_init,
+                                            rcutorture_booster_cleanup);
+               if (firsterr < 0)
+                       goto unwind;
+               rcutor_hp = firsterr;
        }
        firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
        if (firsterr)
index e5164deb51e1e2e7f8079e41fed5cc2678ea4b4b..96c52e43f7cac0e5d6b41004c0c72d269c351f4a 100644 (file)
@@ -41,7 +41,6 @@
 #include <linux/export.h>
 #include <linux/completion.h>
 #include <linux/moduleparam.h>
-#include <linux/module.h>
 #include <linux/percpu.h>
 #include <linux/notifier.h>
 #include <linux/cpu.h>
@@ -60,7 +59,6 @@
 #include "tree.h"
 #include "rcu.h"
 
-MODULE_ALIAS("rcutree");
 #ifdef MODULE_PARAM_PREFIX
 #undef MODULE_PARAM_PREFIX
 #endif
@@ -1306,7 +1304,8 @@ static void rcu_stall_kick_kthreads(struct rcu_state *rsp)
        if (!rcu_kick_kthreads)
                return;
        j = READ_ONCE(rsp->jiffies_kick_kthreads);
-       if (time_after(jiffies, j) && rsp->gp_kthread) {
+       if (time_after(jiffies, j) && rsp->gp_kthread &&
+           (rcu_gp_in_progress(rsp) || READ_ONCE(rsp->gp_flags))) {
                WARN_ONCE(1, "Kicking %s grace-period kthread\n", rsp->name);
                rcu_ftrace_dump(DUMP_ALL);
                wake_up_process(rsp->gp_kthread);
@@ -1848,6 +1847,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
                              struct rcu_data *rdp)
 {
        bool ret;
+       bool need_gp;
 
        /* Handle the ends of any preceding grace periods first. */
        if (rdp->completed == rnp->completed &&
@@ -1874,9 +1874,10 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
                 */
                rdp->gpnum = rnp->gpnum;
                trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpustart"));
-               rdp->cpu_no_qs.b.norm = true;
+               need_gp = !!(rnp->qsmask & rdp->grpmask);
+               rdp->cpu_no_qs.b.norm = need_gp;
                rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
-               rdp->core_needs_qs = !!(rnp->qsmask & rdp->grpmask);
+               rdp->core_needs_qs = need_gp;
                zero_cpu_stall_ticks(rdp);
                WRITE_ONCE(rdp->gpwrap, false);
        }
@@ -2344,7 +2345,7 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
        WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
        WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
        raw_spin_unlock_irqrestore_rcu_node(rcu_get_root(rsp), flags);
-       swake_up(&rsp->gp_wq);  /* Memory barrier implied by swake_up() path. */
+       rcu_gp_kthread_wake(rsp);
 }
 
 /*
@@ -2828,8 +2829,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
  * Also schedule RCU core processing.
  *
  * This function must be called from hardirq context.  It is normally
- * invoked from the scheduling-clock interrupt.  If rcu_pending returns
- * false, there is no point in invoking rcu_check_callbacks().
+ * invoked from the scheduling-clock interrupt.
  */
 void rcu_check_callbacks(int user)
 {
@@ -2970,7 +2970,7 @@ static void force_quiescent_state(struct rcu_state *rsp)
        }
        WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
        raw_spin_unlock_irqrestore_rcu_node(rnp_old, flags);
-       swake_up(&rsp->gp_wq); /* Memory barrier implied by swake_up() path. */
+       rcu_gp_kthread_wake(rsp);
 }
 
 /*
@@ -3121,7 +3121,9 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func,
        unsigned long flags;
        struct rcu_data *rdp;
 
-       WARN_ON_ONCE((unsigned long)head & 0x1); /* Misaligned rcu_head! */
+       /* Misaligned rcu_head! */
+       WARN_ON_ONCE((unsigned long)head & (sizeof(void *) - 1));
+
        if (debug_rcu_head_queue(head)) {
                /* Probable double call_rcu(), so leak the callback. */
                WRITE_ONCE(head->func, rcu_leak_callback);
@@ -3130,13 +3132,6 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func,
        }
        head->func = func;
        head->next = NULL;
-
-       /*
-        * Opportunistically note grace-period endings and beginnings.
-        * Note that we might see a beginning right after we see an
-        * end, but never vice versa, since this CPU has to pass through
-        * a quiescent state betweentimes.
-        */
        local_irq_save(flags);
        rdp = this_cpu_ptr(rsp->rda);
 
@@ -3792,8 +3787,6 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
        rnp = rdp->mynode;
        mask = rdp->grpmask;
        raw_spin_lock_rcu_node(rnp);            /* irqs already disabled. */
-       rnp->qsmaskinitnext |= mask;
-       rnp->expmaskinitnext |= mask;
        if (!rdp->beenonline)
                WRITE_ONCE(rsp->ncpus, READ_ONCE(rsp->ncpus) + 1);
        rdp->beenonline = true;  /* We have now been online. */
@@ -3860,6 +3853,32 @@ int rcutree_dead_cpu(unsigned int cpu)
        return 0;
 }
 
+/*
+ * Mark the specified CPU as being online so that subsequent grace periods
+ * (both expedited and normal) will wait on it.  Note that this means that
+ * incoming CPUs are not allowed to use RCU read-side critical sections
+ * until this function is called.  Failing to observe this restriction
+ * will result in lockdep splats.
+ */
+void rcu_cpu_starting(unsigned int cpu)
+{
+       unsigned long flags;
+       unsigned long mask;
+       struct rcu_data *rdp;
+       struct rcu_node *rnp;
+       struct rcu_state *rsp;
+
+       for_each_rcu_flavor(rsp) {
+               rdp = this_cpu_ptr(rsp->rda);
+               rnp = rdp->mynode;
+               mask = rdp->grpmask;
+               raw_spin_lock_irqsave_rcu_node(rnp, flags);
+               rnp->qsmaskinitnext |= mask;
+               rnp->expmaskinitnext |= mask;
+               raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
+       }
+}
+
 #ifdef CONFIG_HOTPLUG_CPU
 /*
  * The CPU is exiting the idle loop into the arch_cpu_idle_dead()
@@ -4209,8 +4228,10 @@ void __init rcu_init(void)
         * or the scheduler are operational.
         */
        pm_notifier(rcu_pm_notify, 0);
-       for_each_online_cpu(cpu)
+       for_each_online_cpu(cpu) {
                rcutree_prepare_cpu(cpu);
+               rcu_cpu_starting(cpu);
+       }
 }
 
 #include "tree_exp.h"
index f714f873bf9daea68d6e469a9fa3d8ef38c1f125..e99a5234d9ed86261cc56a882e42f957079cc87d 100644 (file)
@@ -400,6 +400,7 @@ struct rcu_data {
 #ifdef CONFIG_RCU_FAST_NO_HZ
        struct rcu_head oom_head;
 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
+       atomic_long_t exp_workdone0;    /* # done by workqueue. */
        atomic_long_t exp_workdone1;    /* # done by others #1. */
        atomic_long_t exp_workdone2;    /* # done by others #2. */
        atomic_long_t exp_workdone3;    /* # done by others #3. */
index 6d86ab6ec2c9792a206f8d7236e48b40f7e258b3..24343eb87b582e4f1dd5d436e6d7ef830e935c19 100644 (file)
@@ -359,7 +359,8 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
                        struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
 
                        if (raw_smp_processor_id() == cpu ||
-                           !(atomic_add_return(0, &rdtp->dynticks) & 0x1))
+                           !(atomic_add_return(0, &rdtp->dynticks) & 0x1) ||
+                           !(rnp->qsmaskinitnext & rdp->grpmask))
                                mask_ofl_test |= rdp->grpmask;
                }
                mask_ofl_ipi = rnp->expmask & ~mask_ofl_test;
@@ -384,17 +385,16 @@ retry_ipi:
                                mask_ofl_ipi &= ~mask;
                                continue;
                        }
-                       /* Failed, raced with offline. */
+                       /* Failed, raced with CPU hotplug operation. */
                        raw_spin_lock_irqsave_rcu_node(rnp, flags);
-                       if (cpu_online(cpu) &&
+                       if ((rnp->qsmaskinitnext & mask) &&
                            (rnp->expmask & mask)) {
+                               /* Online, so delay for a bit and try again. */
                                raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
                                schedule_timeout_uninterruptible(1);
-                               if (cpu_online(cpu) &&
-                                   (rnp->expmask & mask))
-                                       goto retry_ipi;
-                               raw_spin_lock_irqsave_rcu_node(rnp, flags);
+                               goto retry_ipi;
                        }
+                       /* CPU really is offline, so we can ignore it. */
                        if (!(rnp->expmask & mask))
                                mask_ofl_ipi &= ~mask;
                        raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
@@ -427,12 +427,10 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
                                jiffies_stall);
                if (ret > 0 || sync_rcu_preempt_exp_done(rnp_root))
                        return;
-               if (ret < 0) {
-                       /* Hit a signal, disable CPU stall warnings. */
-                       swait_event(rsp->expedited_wq,
-                                  sync_rcu_preempt_exp_done(rnp_root));
-                       return;
-               }
+               WARN_ON(ret < 0);  /* workqueues should not be signaled. */
+               if (rcu_cpu_stall_suppress)
+                       continue;
+               panic_on_rcu_stall();
                pr_err("INFO: %s detected expedited stalls on CPUs/tasks: {",
                       rsp->name);
                ndetected = 0;
@@ -500,7 +498,6 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s)
         * next GP, to proceed.
         */
        mutex_lock(&rsp->exp_wake_mutex);
-       mutex_unlock(&rsp->exp_mutex);
 
        rcu_for_each_node_breadth_first(rsp, rnp) {
                if (ULONG_CMP_LT(READ_ONCE(rnp->exp_seq_rq), s)) {
@@ -516,6 +513,70 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s)
        mutex_unlock(&rsp->exp_wake_mutex);
 }
 
+/* Let the workqueue handler know what it is supposed to do. */
+struct rcu_exp_work {
+       smp_call_func_t rew_func;
+       struct rcu_state *rew_rsp;
+       unsigned long rew_s;
+       struct work_struct rew_work;
+};
+
+/*
+ * Work-queue handler to drive an expedited grace period forward.
+ */
+static void wait_rcu_exp_gp(struct work_struct *wp)
+{
+       struct rcu_exp_work *rewp;
+
+       /* Initialize the rcu_node tree in preparation for the wait. */
+       rewp = container_of(wp, struct rcu_exp_work, rew_work);
+       sync_rcu_exp_select_cpus(rewp->rew_rsp, rewp->rew_func);
+
+       /* Wait and clean up, including waking everyone. */
+       rcu_exp_wait_wake(rewp->rew_rsp, rewp->rew_s);
+}
+
+/*
+ * Given an rcu_state pointer and a smp_call_function() handler, kick
+ * off the specified flavor of expedited grace period.
+ */
+static void _synchronize_rcu_expedited(struct rcu_state *rsp,
+                                      smp_call_func_t func)
+{
+       struct rcu_data *rdp;
+       struct rcu_exp_work rew;
+       struct rcu_node *rnp;
+       unsigned long s;
+
+       /* If expedited grace periods are prohibited, fall back to normal. */
+       if (rcu_gp_is_normal()) {
+               wait_rcu_gp(rsp->call);
+               return;
+       }
+
+       /* Take a snapshot of the sequence number.  */
+       s = rcu_exp_gp_seq_snap(rsp);
+       if (exp_funnel_lock(rsp, s))
+               return;  /* Someone else did our work for us. */
+
+       /* Marshall arguments and schedule the expedited grace period. */
+       rew.rew_func = func;
+       rew.rew_rsp = rsp;
+       rew.rew_s = s;
+       INIT_WORK_ONSTACK(&rew.rew_work, wait_rcu_exp_gp);
+       schedule_work(&rew.rew_work);
+
+       /* Wait for expedited grace period to complete. */
+       rdp = per_cpu_ptr(rsp->rda, raw_smp_processor_id());
+       rnp = rcu_get_root(rsp);
+       wait_event(rnp->exp_wq[(s >> 1) & 0x3],
+                  sync_exp_work_done(rsp,
+                                     &rdp->exp_workdone0, s));
+
+       /* Let the next expedited grace period start. */
+       mutex_unlock(&rsp->exp_mutex);
+}
+
 /**
  * synchronize_sched_expedited - Brute-force RCU-sched grace period
  *
@@ -534,29 +595,13 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s)
  */
 void synchronize_sched_expedited(void)
 {
-       unsigned long s;
        struct rcu_state *rsp = &rcu_sched_state;
 
        /* If only one CPU, this is automatically a grace period. */
        if (rcu_blocking_is_gp())
                return;
 
-       /* If expedited grace periods are prohibited, fall back to normal. */
-       if (rcu_gp_is_normal()) {
-               wait_rcu_gp(call_rcu_sched);
-               return;
-       }
-
-       /* Take a snapshot of the sequence number.  */
-       s = rcu_exp_gp_seq_snap(rsp);
-       if (exp_funnel_lock(rsp, s))
-               return;  /* Someone else did our work for us. */
-
-       /* Initialize the rcu_node tree in preparation for the wait. */
-       sync_rcu_exp_select_cpus(rsp, sync_sched_exp_handler);
-
-       /* Wait and clean up, including waking everyone. */
-       rcu_exp_wait_wake(rsp, s);
+       _synchronize_rcu_expedited(rsp, sync_sched_exp_handler);
 }
 EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
 
@@ -620,23 +665,8 @@ static void sync_rcu_exp_handler(void *info)
 void synchronize_rcu_expedited(void)
 {
        struct rcu_state *rsp = rcu_state_p;
-       unsigned long s;
-
-       /* If expedited grace periods are prohibited, fall back to normal. */
-       if (rcu_gp_is_normal()) {
-               wait_rcu_gp(call_rcu);
-               return;
-       }
-
-       s = rcu_exp_gp_seq_snap(rsp);
-       if (exp_funnel_lock(rsp, s))
-               return;  /* Someone else did our work for us. */
-
-       /* Initialize the rcu_node tree in preparation for the wait. */
-       sync_rcu_exp_select_cpus(rsp, sync_rcu_exp_handler);
 
-       /* Wait for ->blkd_tasks lists to drain, then wake everyone up. */
-       rcu_exp_wait_wake(rsp, s);
+       _synchronize_rcu_expedited(rsp, sync_rcu_exp_handler);
 }
 EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
 
index 0082fce402a0c11c922648ae0d90a9d2bd85561f..85c5a883c6e31047194a8c74603ce71ab8381f67 100644 (file)
@@ -2173,6 +2173,7 @@ static int rcu_nocb_kthread(void *arg)
                                cl++;
                        c++;
                        local_bh_enable();
+                       cond_resched_rcu_qs();
                        list = next;
                }
                trace_rcu_batch_end(rdp->rsp->name, c, !!list, 0, 0, 1);
index 86782f9a460432614725f0e234785a6b49d9f0db..b1f28972872cb1fe3edd4a835ad3cbb5d692886a 100644 (file)
@@ -185,16 +185,17 @@ static int show_rcuexp(struct seq_file *m, void *v)
        int cpu;
        struct rcu_state *rsp = (struct rcu_state *)m->private;
        struct rcu_data *rdp;
-       unsigned long s1 = 0, s2 = 0, s3 = 0;
+       unsigned long s0 = 0, s1 = 0, s2 = 0, s3 = 0;
 
        for_each_possible_cpu(cpu) {
                rdp = per_cpu_ptr(rsp->rda, cpu);
+               s0 += atomic_long_read(&rdp->exp_workdone0);
                s1 += atomic_long_read(&rdp->exp_workdone1);
                s2 += atomic_long_read(&rdp->exp_workdone2);
                s3 += atomic_long_read(&rdp->exp_workdone3);
        }
-       seq_printf(m, "s=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n",
-                  rsp->expedited_sequence, s1, s2, s3,
+       seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n",
+                  rsp->expedited_sequence, s0, s1, s2, s3,
                   atomic_long_read(&rsp->expedited_normal),
                   atomic_read(&rsp->expedited_need_qs),
                   rsp->expedited_sequence / 2);
index f0d8322bc3ec179f7a3cfa2f9bef7a0d8f8cb950..f19271dce0a9784709d7bc7860a2de972e67a070 100644 (file)
@@ -46,7 +46,7 @@
 #include <linux/export.h>
 #include <linux/hardirq.h>
 #include <linux/delay.h>
-#include <linux/module.h>
+#include <linux/moduleparam.h>
 #include <linux/kthread.h>
 #include <linux/tick.h>
 
@@ -54,7 +54,6 @@
 
 #include "rcu.h"
 
-MODULE_ALIAS("rcupdate");
 #ifdef MODULE_PARAM_PREFIX
 #undef MODULE_PARAM_PREFIX
 #endif
diff --git a/kernel/rcu/waketorture.c b/kernel/rcu/waketorture.c
new file mode 100644 (file)
index 0000000..68be404
--- /dev/null
@@ -0,0 +1,537 @@
+/*
+ * Specific stress-testing of wakeup logic in the presence of hotplug
+ * operations.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you can access it online at
+ * http://www.gnu.org/licenses/gpl-2.0.html.
+ *
+ * Copyright (C) IBM Corporation, 2016
+ *
+ * Author: Paul E. McKenney <paulmck@us.ibm.com>
+ */
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/err.h>
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <linux/rcupdate.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/atomic.h>
+#include <linux/bitops.h>
+#include <linux/completion.h>
+#include <linux/moduleparam.h>
+#include <linux/percpu.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/freezer.h>
+#include <linux/cpu.h>
+#include <linux/delay.h>
+#include <linux/stat.h>
+#include <linux/srcu.h>
+#include <linux/slab.h>
+#include <linux/trace_clock.h>
+#include <asm/byteorder.h>
+#include <linux/torture.h>
+#include <linux/vmalloc.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
+
+
+torture_param(int, nwaiters, -1, "Number of timed-wait threads");
+torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
+torture_param(int, onoff_interval, 0,
+            "Time between CPU hotplugs (jiffies), 0=disable");
+torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
+torture_param(int, stat_interval, 60,
+            "Number of seconds between stats printk()s");
+torture_param(bool, verbose, true,
+            "Enable verbose debugging printk()s");
+torture_param(int, wait_duration, 127,
+            "Number of microseconds to wait each iteration");
+torture_param(int, wait_grace, 20,
+            "Number of jiffies before complaining about long wait");
+
+static char *torture_type = "sh";
+module_param(torture_type, charp, 0444);
+MODULE_PARM_DESC(torture_type, "Type of wait to torture (sti, stui, ...)");
+
+static int nrealwaiters;
+static struct task_struct **waiter_tasks;
+static struct task_struct *stats_task;
+static struct task_struct *onoff_task;
+
+/* Yes, these cache-thrash, and it is inherent to the concurrency design. */
+static bool *waiter_done;              /* Waiter is done, don't wake. */
+static unsigned long *waiter_iter;     /* Number of wait iterations. */
+static bool *waiter_cts;               /* Waiter already checked. */
+static unsigned long *waiter_kicks;    /* Number of waiter starvations. */
+static unsigned long *waiter_ts;       /* Jiffies last run. */
+static DEFINE_MUTEX(waiter_mutex);
+static DEFINE_PER_CPU(u64, waiter_cputime); /* Nanoseconds. */
+static u64 starttime;
+
+static int onoff_cpu = -1;
+static long n_offline_attempts;
+static long n_offline_successes;
+static unsigned long sum_offline;
+static int min_offline = -1;
+static int max_offline;
+static long n_online_attempts;
+static long n_online_successes;
+static unsigned long sum_online;
+static int min_online = -1;
+static int max_online;
+
+static int torture_runnable = IS_ENABLED(MODULE);
+module_param(torture_runnable, int, 0444);
+MODULE_PARM_DESC(torture_runnable, "Start waketorture at boot");
+
+/*
+ * Operations vector for selecting different types of tests.
+ */
+
+struct wake_torture_ops {
+       void (*wait)(void);
+       const char *name;
+};
+
+static struct wake_torture_ops *cur_ops;
+
+/*
+ * Definitions for schedule_hrtimeout() torture testing.
+ */
+
+static void wait_schedule_hrtimeout(void)
+{
+       ktime_t wait = ns_to_ktime(wait_duration * 1000);
+
+       set_current_state(TASK_UNINTERRUPTIBLE);
+       schedule_hrtimeout(&wait, HRTIMER_MODE_REL);
+}
+
+static struct wake_torture_ops sh_ops = {
+       .wait           = wait_schedule_hrtimeout,
+       .name           = "sh"
+};
+
+/*
+ * Definitions for schedule_timeout_interruptible() torture testing.
+ */
+
+static void wait_schedule_timeout_interruptible(void)
+{
+       schedule_timeout_interruptible((wait_duration + 999) / 1000);
+}
+
+static struct wake_torture_ops sti_ops = {
+       .wait           = wait_schedule_timeout_interruptible,
+       .name           = "sti"
+};
+
+/*
+ * Definitions for schedule_timeout_uninterruptible() torture testing.
+ */
+
+static void wait_schedule_timeout_uninterruptible(void)
+{
+       schedule_timeout_uninterruptible((wait_duration + 999) / 1000);
+}
+
+static struct wake_torture_ops stui_ops = {
+       .wait           = wait_schedule_timeout_uninterruptible,
+       .name           = "stui"
+};
+
+/*
+ * Has the specified waiter thread run recently?
+ */
+static bool kthread_ran_recently(int tnum)
+{
+       smp_mb(); /* Ensure waiter_cts[] read before waiter_ts[].  [A] */
+       return time_before(READ_ONCE(waiter_ts[tnum]), jiffies + wait_grace);
+}
+
+/*
+ * Wakeup torture fake writer kthread.  Repeatedly calls sync, with a random
+ * delay between calls.
+ */
+static int wake_torture_waiter(void *arg)
+{
+       int i;
+       long me = (long)arg;
+       u64 ts;
+
+       VERBOSE_TOROUT_STRING("wake_torture_waiter task started");
+       set_user_nice(current, MAX_NICE);
+
+       preempt_disable();
+       ts = trace_clock_local();
+       do {
+               waiter_ts[me] = jiffies;
+               smp_mb(); /* Ensure waiter_ts[] written before waiter_cts[]. */
+                         /* Pairs with [A]. */
+               waiter_cts[me] = false;
+               __this_cpu_add(waiter_cputime, trace_clock_local() - ts);
+               preempt_enable();
+               cur_ops->wait();
+               preempt_disable();
+               ts = trace_clock_local();
+               waiter_iter[me]++;
+               for (i = 0; i < nrealwaiters; i++) {
+                       if (waiter_done[i] ||
+                           waiter_cts[i] ||
+                           kthread_ran_recently(i))
+                               continue;
+                       if (!mutex_trylock(&waiter_mutex)) {
+                               break; /* Keep lock contention to dull roar. */
+                       } else if (waiter_done[i] ||
+                                  waiter_cts[i] ||
+                                  kthread_ran_recently(i)) {
+                               mutex_unlock(&waiter_mutex);
+                       } else {
+                               waiter_cts[i] = true;
+                               waiter_kicks[i]++;
+                               pr_alert("%s%s wake_torture_waiter(): P%d (%#lx) failing to awaken!\n",
+                                        torture_type, TORTURE_FLAG,
+                                        waiter_tasks[i]->pid,
+                                        waiter_tasks[i]->state);
+                               rcu_ftrace_dump(DUMP_ALL);
+                               wake_up_process(waiter_tasks[i]);
+                               mutex_unlock(&waiter_mutex);
+                       }
+               }
+               __this_cpu_add(waiter_cputime, trace_clock_local() - ts);
+               preempt_enable();
+               torture_shutdown_absorb("wake_torture_waiter");
+               preempt_disable();
+               ts = trace_clock_local();
+       } while (!torture_must_stop());
+       __this_cpu_add(waiter_cputime, trace_clock_local() - ts);
+       preempt_enable();
+       mutex_lock(&waiter_mutex);
+       waiter_done[me] = true;
+       mutex_unlock(&waiter_mutex);
+       torture_kthread_stopping("wake_torture_waiter");
+       return 0;
+}
+
+/*
+ * Find a hotpluggable CPU and repeatedly take it online and offline.
+ */
+static int wake_torture_onoff(void *args)
+{
+       cpumask_var_t cm;
+       int cpu;
+       int i;
+
+       VERBOSE_TOROUT_STRING("wake_torture_onoff task started");
+       if (onoff_holdoff > 0) {
+               VERBOSE_TOROUT_STRING("wake_torture_onoff begin holdoff");
+               schedule_timeout_interruptible(onoff_holdoff * HZ);
+               VERBOSE_TOROUT_STRING("wake_torture_onoff end holdoff");
+       }
+
+       /*
+        * Find the last hotpluggable CPU, and affinity the waiter
+        * tasks elsewhere.
+        */
+       for_each_online_cpu(cpu) {
+               if (cpu_is_hotpluggable(cpu))
+                       onoff_cpu = cpu;
+       }
+       if (onoff_cpu < 0) {
+               VERBOSE_TOROUT_STRING("wake_torture_onoff: no hotpluggable CPUs!");
+               if (shutdown_secs > 0) {
+                       VERBOSE_TOROUT_STRING("wake_torture_onoff: Shutting down");
+                       kernel_power_off();
+                       VERBOSE_TOROUT_STRING("wake_torture_onoff: Survived kernel_power_off()?");
+               }
+       }
+       pr_alert("%s" TORTURE_FLAG " wake_torture_onoff: onoff_cpu: %d\n", torture_type, onoff_cpu);
+       if (!zalloc_cpumask_var(&cm, GFP_KERNEL)) {
+               VERBOSE_TOROUT_STRING("wake_torture_onoff: Out of memory, no affinity");
+       } else {
+               cpumask_copy(cm, cpu_online_mask);
+               cpumask_clear_cpu(onoff_cpu, cm);
+               if (cpumask_weight(cm) == 0)
+                       cpumask_setall(cm);
+               for (i = 0; i < nrealwaiters; i++)
+                       set_cpus_allowed_ptr(waiter_tasks[i], cm);
+       }
+
+       /* Cycle the victim CPU online and offline! */
+       while (!torture_must_stop() && onoff_cpu >= 0) {
+               if (!torture_offline(onoff_cpu,
+                                   &n_offline_attempts, &n_offline_successes,
+                                   &sum_offline, &min_offline, &max_offline))
+                       torture_online(onoff_cpu,
+                                      &n_online_attempts, &n_online_successes,
+                                      &sum_online, &min_online, &max_online);
+               schedule_timeout_interruptible(onoff_interval);
+       }
+       torture_kthread_stopping("wake_torture_onoff");
+       return 0;
+}
+
+/*
+ * Initiate waketorture-specific online-offline handling, which
+ * focuses on a single CPU.
+ */
+static int wake_torture_onoff_init(void)
+{
+       int ret = 0;
+
+       if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
+               return ret;
+       if (onoff_interval <= 0)
+               return 0;
+       ret = torture_create_kthread(wake_torture_onoff, NULL, onoff_task);
+       return ret;
+}
+
+/*
+ * Clean up after waketorture-specific online-offline handling.
+ */
+static void wake_torture_onoff_cleanup(void)
+{
+       if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
+               return;
+       VERBOSE_TOROUT_STRING("Stopping wake_torture_onoff task");
+       kthread_stop(onoff_task);
+       onoff_task = NULL;
+}
+
+/*
+ * Print torture statistics.  Caller must ensure that there is only one
+ * call to this function at a given time!!!  This is normally accomplished
+ * by relying on the module system to only have one copy of the module
+ * loaded, and then by giving the wake_torture_stats kthread full control
+ * (or the init/cleanup functions when wake_torture_stats thread is not
+ * running).
+ *
+ * Note that some care is required because this can be called once during
+ * cleanup processing after a failed startup attempt.
+ */
+static void
+wake_torture_stats_print(void)
+{
+       int i;
+       bool tardy = false;
+       u64 timediff;
+       u64 timetot;
+
+       if (!waiter_done || !waiter_iter || !waiter_cts ||
+           !waiter_kicks || !waiter_ts) {
+               TOROUT_STRING("Partial initialization, no stats print.\n");
+               return;
+       }
+       for (i = 0; i < nrealwaiters; i++)
+               if (waiter_kicks[i]) {
+                       if (!tardy)
+                               pr_alert("%s" TORTURE_FLAG " Tardy kthreads:",
+                                        torture_type);
+                       tardy = true;
+                       pr_cont("  P%d%c: %lud/%lu",
+                               waiter_tasks && waiter_tasks[i]
+                                       ? waiter_tasks[i]->pid
+                                       : -1,
+                               "!."[kthread_ran_recently(i)],
+                               waiter_kicks[i], waiter_iter[i]);
+               }
+       if (tardy)
+               pr_cont("\n");
+       else
+               TOROUT_STRING(" No tardy kthreads");
+       timediff = (trace_clock_global() - starttime) / 1000;
+       timetot = 0;
+       for_each_possible_cpu(i)
+               timetot += READ_ONCE(per_cpu(waiter_cputime, i));
+       timetot /= nr_cpu_ids;
+       timetot /= timediff;
+       pr_alert("%s" TORTURE_FLAG " timediff: %llu utilization: %llu.%llu nr_cpu_ids: %d onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d)\n",
+                torture_type, timediff,
+                timetot / 1000ULL, timetot % 1000ULL, nr_cpu_ids,
+                n_online_successes, n_online_attempts,
+                n_offline_successes, n_offline_attempts,
+                min_online, max_online,
+                min_offline, max_offline,
+                sum_online, sum_offline, HZ);
+}
+
+/*
+ * Periodically prints torture statistics, if periodic statistics printing
+ * was specified via the stat_interval module parameter.
+ */
+static int
+wake_torture_stats(void *arg)
+{
+       VERBOSE_TOROUT_STRING("wake_torture_stats task started");
+       do {
+               schedule_timeout_interruptible(stat_interval * HZ);
+               wake_torture_stats_print();
+               torture_shutdown_absorb("wake_torture_stats");
+       } while (!torture_must_stop());
+       torture_kthread_stopping("wake_torture_stats");
+       return 0;
+}
+
+static inline void
+wake_torture_print_module_parms(struct wake_torture_ops *cur_ops,
+                               const char *tag)
+{
+       pr_alert("%s" TORTURE_FLAG
+                "--- %s: nwaiters=%d onoff_holdoff=%d onoff_interval=%d shutdown_secs=%d stat_interval=%d verbose=%d wait_duration=%d wait_grace=%d\n",
+                torture_type, tag,
+                nrealwaiters, onoff_holdoff, onoff_interval,
+                shutdown_secs, stat_interval, verbose,
+                wait_duration, wait_grace);
+}
+
+static void
+wake_torture_cleanup(void)
+{
+       int i;
+       bool success;
+
+       (void)torture_cleanup_begin();
+
+       if (onoff_task)
+               wake_torture_onoff_cleanup();
+
+       if (waiter_tasks) {
+               for (i = 0; i < nrealwaiters; i++)
+                       torture_stop_kthread(wake_torture_waiter,
+                                            waiter_tasks[i]);
+               kfree(waiter_tasks);
+       }
+
+       torture_stop_kthread(wake_torture_stats, stats_task);
+
+       wake_torture_stats_print();  /* -After- the stats thread is stopped! */
+
+       success = !!waiter_kicks;
+       for (i = 0; i < nrealwaiters; i++)
+               if (!success || waiter_kicks[i]) {
+                       success = false;
+                       break;
+               }
+
+       kfree(waiter_done);
+       kfree(waiter_iter);
+       kfree(waiter_cts);
+       kfree(waiter_kicks);
+       kfree(waiter_ts);
+
+       wake_torture_print_module_parms(cur_ops,
+                                       success ? "End of test: SUCCESS"
+                                               : "End of test: FAILURE");
+       torture_cleanup_end();
+}
+
+static int __init
+wake_torture_init(void)
+{
+       int i;
+       int firsterr = 0;
+       static struct wake_torture_ops *torture_ops[] = {
+               &sh_ops, &sti_ops, &stui_ops
+       };
+
+       if (!torture_init_begin(torture_type, verbose, &torture_runnable))
+               return -EBUSY;
+       starttime = trace_clock_global();
+
+       /* Process args and tell the world that the torturer is on the job. */
+       for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
+               cur_ops = torture_ops[i];
+               if (strcmp(torture_type, cur_ops->name) == 0)
+                       break;
+       }
+       if (i == ARRAY_SIZE(torture_ops)) {
+               pr_alert("wake-torture: invalid torture type: \"%s\"\n",
+                        torture_type);
+               pr_alert("wake-torture types:");
+               for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
+                       pr_alert(" %s", torture_ops[i]->name);
+               pr_alert("\n");
+               firsterr = -EINVAL;
+               goto unwind;
+       }
+
+       if (nwaiters >= 0) {
+               nrealwaiters = nwaiters;
+       } else {
+               nrealwaiters = num_online_cpus() - 2 - nwaiters;
+               if (nrealwaiters <= 0)
+                       nrealwaiters = 1;
+       }
+       wake_torture_print_module_parms(cur_ops, "Start of test");
+
+       /* Initialize the statistics so that each run gets its own numbers. */
+
+       waiter_done = kcalloc(nrealwaiters, sizeof(*waiter_done), GFP_KERNEL);
+       waiter_iter = kcalloc(nrealwaiters, sizeof(*waiter_iter), GFP_KERNEL);
+       waiter_cts = kcalloc(nrealwaiters, sizeof(*waiter_cts), GFP_KERNEL);
+       waiter_kicks = kcalloc(nrealwaiters, sizeof(*waiter_kicks), GFP_KERNEL);
+       waiter_ts = kcalloc(nrealwaiters, sizeof(*waiter_ts), GFP_KERNEL);
+       if (!waiter_done || !waiter_iter || !waiter_cts || !waiter_kicks ||
+           !waiter_ts) {
+               VERBOSE_TOROUT_ERRSTRING("out of memory");
+               firsterr = -ENOMEM;
+               goto unwind;
+       }
+
+       /* Start up the kthreads. */
+
+       waiter_tasks = kcalloc(nrealwaiters, sizeof(waiter_tasks[0]),
+                              GFP_KERNEL);
+       if (!waiter_tasks) {
+               VERBOSE_TOROUT_ERRSTRING("out of memory");
+               firsterr = -ENOMEM;
+               goto unwind;
+       }
+       for (i = 0; i < nrealwaiters; i++) {
+               firsterr = torture_create_kthread(wake_torture_waiter,
+                                                 NULL, waiter_tasks[i]);
+               if (firsterr)
+                       goto unwind;
+       }
+       if (stat_interval > 0) {
+               firsterr = torture_create_kthread(wake_torture_stats, NULL,
+                                                 stats_task);
+               if (firsterr)
+                       goto unwind;
+       }
+       firsterr = torture_shutdown_init(shutdown_secs, wake_torture_cleanup);
+       if (firsterr)
+               goto unwind;
+       firsterr = wake_torture_onoff_init();
+       if (firsterr)
+               goto unwind;
+       torture_init_end();
+       return 0;
+
+unwind:
+       torture_init_end();
+       wake_torture_cleanup();
+       return firsterr;
+}
+
+module_init(wake_torture_init);
+module_exit(wake_torture_cleanup);
index a0086a5fc00893d63f1b0c42ac85f63508d07a2d..f5f7b3cdf0be0577d69fc44e4390e7d9a1e75c88 100644 (file)
@@ -581,6 +581,8 @@ static bool wake_up_full_nohz_cpu(int cpu)
         * If needed we can still optimize that later with an
         * empty IRQ.
         */
+       if (cpu_is_offline(cpu))
+               return true;  /* Don't try to wake offline CPUs. */
        if (tick_nohz_full_cpu(cpu)) {
                if (cpu != smp_processor_id() ||
                    tick_nohz_tick_stopped())
@@ -591,6 +593,11 @@ static bool wake_up_full_nohz_cpu(int cpu)
        return false;
 }
 
+/*
+ * Wake up the specified CPU.  If the CPU is going offline, it is the
+ * caller's responsibility to deal with the lost wakeup, for example,
+ * by hooking into the CPU_DEAD notifier like timers and hrtimers do.
+ */
 void wake_up_nohz_cpu(int cpu)
 {
        if (!wake_up_full_nohz_cpu(cpu))
index 75961b3decfe9489cfa08459a8efba8931a0343a..0d887eb62856e38761aa840ab22347cdc98c1c90 100644 (file)
@@ -43,6 +43,7 @@
 #include <linux/stat.h>
 #include <linux/slab.h>
 #include <linux/trace_clock.h>
+#include <linux/ktime.h>
 #include <asm/byteorder.h>
 #include <linux/torture.h>
 
@@ -446,9 +447,8 @@ EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
  * Variables for auto-shutdown.  This allows "lights out" torture runs
  * to be fully scripted.
  */
-static int shutdown_secs;              /* desired test duration in seconds. */
 static struct task_struct *shutdown_task;
-static unsigned long shutdown_time;    /* jiffies to system shutdown. */
+static ktime_t shutdown_time;          /* time to system shutdown. */
 static void (*torture_shutdown_hook)(void);
 
 /*
@@ -471,20 +471,20 @@ EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
  */
 static int torture_shutdown(void *arg)
 {
-       long delta;
-       unsigned long jiffies_snap;
+       ktime_t ktime_snap;
 
        VERBOSE_TOROUT_STRING("torture_shutdown task started");
-       jiffies_snap = jiffies;
-       while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
+       ktime_snap = ktime_get();
+       while (ktime_before(ktime_snap, shutdown_time) &&
               !torture_must_stop()) {
-               delta = shutdown_time - jiffies_snap;
                if (verbose)
                        pr_alert("%s" TORTURE_FLAG
-                                "torture_shutdown task: %lu jiffies remaining\n",
-                                torture_type, delta);
-               schedule_timeout_interruptible(delta);
-               jiffies_snap = jiffies;
+                                "torture_shutdown task: %llu ms remaining\n",
+                                torture_type,
+                                ktime_ms_delta(shutdown_time, ktime_snap));
+               set_current_state(TASK_INTERRUPTIBLE);
+               schedule_hrtimeout(&shutdown_time, HRTIMER_MODE_ABS);
+               ktime_snap = ktime_get();
        }
        if (torture_must_stop()) {
                torture_kthread_stopping("torture_shutdown");
@@ -511,10 +511,9 @@ int torture_shutdown_init(int ssecs, void (*cleanup)(void))
 {
        int ret = 0;
 
-       shutdown_secs = ssecs;
        torture_shutdown_hook = cleanup;
-       if (shutdown_secs > 0) {
-               shutdown_time = jiffies + shutdown_secs * HZ;
+       if (ssecs > 0) {
+               shutdown_time = ktime_add(ktime_get(), ktime_set(ssecs, 0));
                ret = torture_create_kthread(torture_shutdown, NULL,
                                             shutdown_task);
        }
index 2e2cca5092318faf62d10ed96a3b7d0a8b9cc129..785f04c80fcfabfb4b3c14d2b5039a98abb21103 100644 (file)
@@ -1214,7 +1214,7 @@ config DEBUG_BUGVERBOSE
 
 config DEBUG_LIST
        bool "Debug linked list manipulation"
-       depends on DEBUG_KERNEL
+       depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
        help
          Enable this to turn on extended checks in the linked-list
          walking routines.
@@ -1307,6 +1307,7 @@ config TORTURE_TEST
 config RCU_PERF_TEST
        tristate "performance tests for RCU"
        depends on DEBUG_KERNEL
+       depends on !UML
        select TORTURE_TEST
        select SRCU
        select TASKS_RCU
@@ -1324,6 +1325,7 @@ config RCU_PERF_TEST
 config RCU_TORTURE_TEST
        tristate "torture tests for RCU"
        depends on DEBUG_KERNEL
+       depends on !UML
        select TORTURE_TEST
        select SRCU
        select TASKS_RCU
@@ -1413,6 +1415,24 @@ config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
          This option specifies the number of jiffies to wait between
          each rcu_node structure cleanup operation.
 
+config WAKE_TORTURE_TEST
+       tristate "Torture test for wakeups and CPU hotplug"
+       depends on DEBUG_KERNEL
+       depends on 64BIT
+       depends on TRACE_CLOCK
+       select TORTURE_TEST
+       default n
+       help
+         This option provides a kernel module that runs torture tests
+         on wakeups from timed waits in the presence of CPU hotplug.
+         The kernel module may be built after the fact on the running
+         kernel to be tested, if desired.
+
+         Say Y here if you want wakeup torture tests to be built into
+         the kernel.
+         Say M if you want the wakeup torture tests to build as a module.
+         Say N if you are unsure.
+
 config RCU_CPU_STALL_TIMEOUT
        int "RCU CPU stall timeout in seconds"
        depends on RCU_STALL_COMMON
@@ -1969,6 +1989,16 @@ config TEST_STATIC_KEYS
 
          If unsure, say N.
 
+config BUG_ON_DATA_CORRUPTION
+       bool "Trigger a BUG when data corruption is detected"
+       select DEBUG_LIST
+       help
+         Select this option if the kernel should BUG when it encounters
+         data corruption in kernel memory structures when they get checked
+         for validity.
+
+         If unsure, say N.
+
 source "samples/Kconfig"
 
 source "lib/Kconfig.kgdb"
index 3859bf63561c63936947b007fe3ee20e822509a1..7f7bfa55eb6df3e9c9c3c2a244ff02d475197e9d 100644 (file)
@@ -2,8 +2,7 @@
  * Copyright 2006, Red Hat, Inc., Dave Jones
  * Released under the General Public License (GPL).
  *
- * This file contains the linked list implementations for
- * DEBUG_LIST.
+ * This file contains the linked list validation for DEBUG_LIST.
  */
 
 #include <linux/export.h>
 #include <linux/rculist.h>
 
 /*
- * Insert a new entry between two known consecutive entries.
- *
- * This is only for internal list manipulation where we know
- * the prev/next entries already!
+ * Check that the data structures for the list manipulations are reasonably
+ * valid. Failures here indicate memory corruption (and possibly an exploit
+ * attempt).
  */
 
-void __list_add(struct list_head *new,
-                             struct list_head *prev,
-                             struct list_head *next)
+bool __list_add_valid(struct list_head *new, struct list_head *prev,
+                     struct list_head *next)
 {
-       WARN(next->prev != prev,
-               "list_add corruption. next->prev should be "
-               "prev (%p), but was %p. (next=%p).\n",
+       CHECK_DATA_CORRUPTION(next->prev != prev,
+               "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
                prev, next->prev, next);
-       WARN(prev->next != next,
-               "list_add corruption. prev->next should be "
-               "next (%p), but was %p. (prev=%p).\n",
+       CHECK_DATA_CORRUPTION(prev->next != next,
+               "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
                next, prev->next, prev);
-       WARN(new == prev || new == next,
-            "list_add double add: new=%p, prev=%p, next=%p.\n",
-            new, prev, next);
-       next->prev = new;
-       new->next = next;
-       new->prev = prev;
-       WRITE_ONCE(prev->next, new);
+       CHECK_DATA_CORRUPTION(new == prev || new == next,
+               "list_add double add: new=%p, prev=%p, next=%p.\n",
+               new, prev, next);
+
+       return true;
 }
-EXPORT_SYMBOL(__list_add);
+EXPORT_SYMBOL(__list_add_valid);
 
-void __list_del_entry(struct list_head *entry)
+bool __list_del_entry_valid(struct list_head *entry)
 {
        struct list_head *prev, *next;
 
        prev = entry->prev;
        next = entry->next;
 
-       if (WARN(next == LIST_POISON1,
+       CHECK_DATA_CORRUPTION(next == LIST_POISON1,
                "list_del corruption, %p->next is LIST_POISON1 (%p)\n",
-               entry, LIST_POISON1) ||
-           WARN(prev == LIST_POISON2,
+               entry, LIST_POISON1);
+       CHECK_DATA_CORRUPTION(prev == LIST_POISON2,
                "list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
-               entry, LIST_POISON2) ||
-           WARN(prev->next != entry,
-               "list_del corruption. prev->next should be %p, "
-               "but was %p\n", entry, prev->next) ||
-           WARN(next->prev != entry,
-               "list_del corruption. next->prev should be %p, "
-               "but was %p\n", entry, next->prev))
-               return;
-
-       __list_del(prev, next);
-}
-EXPORT_SYMBOL(__list_del_entry);
+               entry, LIST_POISON2);
+       CHECK_DATA_CORRUPTION(prev->next != entry,
+               "list_del corruption. prev->next should be %p, but was %p\n",
+               entry, prev->next);
+       CHECK_DATA_CORRUPTION(next->prev != entry,
+               "list_del corruption. next->prev should be %p, but was %p\n",
+               entry, next->prev);
+       return true;
 
-/**
- * list_del - deletes entry from list.
- * @entry: the element to delete from the list.
- * Note: list_empty on entry does not return true after this, the entry is
- * in an undefined state.
- */
-void list_del(struct list_head *entry)
-{
-       __list_del_entry(entry);
-       entry->next = LIST_POISON1;
-       entry->prev = LIST_POISON2;
-}
-EXPORT_SYMBOL(list_del);
-
-/*
- * RCU variants.
- */
-void __list_add_rcu(struct list_head *new,
-                   struct list_head *prev, struct list_head *next)
-{
-       WARN(next->prev != prev,
-               "list_add_rcu corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
-               prev, next->prev, next);
-       WARN(prev->next != next,
-               "list_add_rcu corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
-               next, prev->next, prev);
-       new->next = next;
-       new->prev = prev;
-       rcu_assign_pointer(list_next_rcu(prev), new);
-       next->prev = new;
 }
-EXPORT_SYMBOL(__list_add_rcu);
+EXPORT_SYMBOL(__list_del_entry_valid);
diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck-wake.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck-wake.sh
new file mode 100755 (executable)
index 0000000..fc9ee19
--- /dev/null
@@ -0,0 +1,39 @@
+#!/bin/bash
+#
+# Analyze a given results directory for waketorture diagnostics.
+#
+# Usage: kvm-recheck-wake resdir
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, you can access it online at
+# http://www.gnu.org/licenses/gpl-2.0.html.
+#
+# Copyright (C) IBM Corporation, 2016
+#
+# Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+
+i="$1"
+if test -d $i
+then
+       :
+else
+       echo Unreadable results directory: $i
+       exit 1
+fi
+PATH=`pwd`/tools/testing/selftests/rcutorture/bin:$PATH; export PATH
+. tools/testing/selftests/rcutorture/bin/functions.sh
+
+configfile=`echo $i | sed -e 's/^.*\///'`
+
+sed -e 's/^\[[^]]*]//' < $i/console.log | grep -e -torture |
+       grep "Tardy kthreads" | tail -1
index f659346d335854328fd1af1e662c21179b4b305c..060c1eec73f49e53cb63b380a4d1a21883c2fb4e 100755 (executable)
@@ -48,7 +48,7 @@ do
                                cat $i/Make.oldconfig.err
                        fi
                        parse-build.sh $i/Make.out $configfile
-                       if test "$TORTURE_SUITE" != rcuperf
+                       if test "$TORTURE_SUITE" != rcuperf -a "$TORTURE_SUITE" != wake
                        then
                                parse-torture.sh $i/console.log $configfile
                        fi
index 0aed965f0062848a0c9899ce94e8687dc3e1b338..0109ddf7b666cf4cb63fabf6c7dcd53c658d931f 100755 (executable)
@@ -163,7 +163,7 @@ do
                shift
                ;;
        --torture)
-               checkarg --torture "(suite name)" "$#" "$2" '^\(lock\|rcu\|rcuperf\)$' '^--'
+               checkarg --torture "(suite name)" "$#" "$2" '^\(lock\|rcu\|rcuperf\|wake\)$' '^--'
                TORTURE_SUITE=$2
                shift
                ;;
diff --git a/tools/testing/selftests/rcutorture/configs/wake/CFLIST b/tools/testing/selftests/rcutorture/configs/wake/CFLIST
new file mode 100644 (file)
index 0000000..850c262
--- /dev/null
@@ -0,0 +1 @@
+STI
diff --git a/tools/testing/selftests/rcutorture/configs/wake/CFcommon b/tools/testing/selftests/rcutorture/configs/wake/CFcommon
new file mode 100644 (file)
index 0000000..ffba181
--- /dev/null
@@ -0,0 +1,2 @@
+CONFIG_WAKE_TORTURE_TEST=y
+CONFIG_PRINTK_TIME=y
diff --git a/tools/testing/selftests/rcutorture/configs/wake/SH b/tools/testing/selftests/rcutorture/configs/wake/SH
new file mode 100644 (file)
index 0000000..7a17c50
--- /dev/null
@@ -0,0 +1,19 @@
+CONFIG_SMP=y
+CONFIG_NR_CPUS=16
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
+#CHECK#CONFIG_PREEMPT_RCU=y
+CONFIG_HZ_PERIODIC=y
+CONFIG_NO_HZ_IDLE=n
+CONFIG_NO_HZ_FULL=n
+CONFIG_RCU_TRACE=y
+CONFIG_HOTPLUG_CPU=y
+CONFIG_RCU_FANOUT=2
+CONFIG_RCU_FANOUT_LEAF=2
+CONFIG_RCU_NOCB_CPU=n
+CONFIG_DEBUG_LOCK_ALLOC=n
+CONFIG_RCU_BOOST=y
+CONFIG_RCU_KTHREAD_PRIO=2
+CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
+CONFIG_RCU_EXPERT=y
diff --git a/tools/testing/selftests/rcutorture/configs/wake/SH.boot b/tools/testing/selftests/rcutorture/configs/wake/SH.boot
new file mode 100644 (file)
index 0000000..a631c87
--- /dev/null
@@ -0,0 +1 @@
+rcupdate.rcu_expedited waketorture.torture_type=sh
diff --git a/tools/testing/selftests/rcutorture/configs/wake/STI b/tools/testing/selftests/rcutorture/configs/wake/STI
new file mode 100644 (file)
index 0000000..7a17c50
--- /dev/null
@@ -0,0 +1,19 @@
+CONFIG_SMP=y
+CONFIG_NR_CPUS=16
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
+#CHECK#CONFIG_PREEMPT_RCU=y
+CONFIG_HZ_PERIODIC=y
+CONFIG_NO_HZ_IDLE=n
+CONFIG_NO_HZ_FULL=n
+CONFIG_RCU_TRACE=y
+CONFIG_HOTPLUG_CPU=y
+CONFIG_RCU_FANOUT=2
+CONFIG_RCU_FANOUT_LEAF=2
+CONFIG_RCU_NOCB_CPU=n
+CONFIG_DEBUG_LOCK_ALLOC=n
+CONFIG_RCU_BOOST=y
+CONFIG_RCU_KTHREAD_PRIO=2
+CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
+CONFIG_RCU_EXPERT=y
diff --git a/tools/testing/selftests/rcutorture/configs/wake/STI.boot b/tools/testing/selftests/rcutorture/configs/wake/STI.boot
new file mode 100644 (file)
index 0000000..67ac1ad
--- /dev/null
@@ -0,0 +1 @@
+rcupdate.rcu_expedited waketorture.torture_type=sti
diff --git a/tools/testing/selftests/rcutorture/configs/wake/ver_functions.sh b/tools/testing/selftests/rcutorture/configs/wake/ver_functions.sh
new file mode 100644 (file)
index 0000000..7331a18
--- /dev/null
@@ -0,0 +1,43 @@
+#!/bin/bash
+#
+# Kernel-version-dependent shell functions for the rest of the scripts.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, you can access it online at
+# http://www.gnu.org/licenses/gpl-2.0.html.
+#
+# Copyright (C) IBM Corporation, 2016
+#
+# Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+
+# waketorture_param_onoff bootparam-string config-file
+#
+# Adds onoff waketorture module parameters to kernels having it.
+waketorture_param_onoff () {
+       if ! bootparam_hotplug_cpu "$1" && configfrag_hotplug_cpu "$2"
+       then
+               echo CPU-hotplug kernel, adding waketorture onoff. 1>&2
+               echo waketorture.onoff_interval=50 waketorture.onoff_holdoff=30
+       fi
+}
+
+# per_version_boot_params bootparam-string config-file seconds
+#
+# Adds per-version torture-module parameters to kernels supporting them.
+per_version_boot_params () {
+       echo $1 `waketorture_param_onoff "$1" "$2"` \
+               waketorture.stat_interval=15 \
+               waketorture.shutdown_secs=$3 \
+               waketorture.torture_runnable=1 \
+               waketorture.verbose=1
+}
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