Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

Pull locking fixes from Ingo Molnar:
 "Two lockdep fixes"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lockdep: Fix lock_chain::base size
  locking/lockdep: Fix ->irq_context calculation

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index d026b190c53066d25753ce98f0d7c66d864a6c0a..d10ef06971b57d8783934333612cb196421716ab 100644 (file)
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -196,9 +196,11 @@ struct lock_list {
  * We record lock dependency chains, so that we can cache them:
  */
 struct lock_chain {
-       u8                              irq_context;
-       u8                              depth;
-       u16                             base;
+       /* see BUILD_BUG_ON()s in lookup_chain_cache() */
+       unsigned int                    irq_context :  2,
+                                       depth       :  6,
+                                       base        : 24;
+       /* 4 byte hole */
        struct hlist_node               entry;
        u64                             chain_key;
 };

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index ed9410936a220632995d40006f024357d5abe38a..78c1c0ee6dc1256904e1afb90611818813fc031c 100644 (file)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2176,15 +2176,37 @@ cache_hit:
        chain->irq_context = hlock->irq_context;
        i = get_first_held_lock(curr, hlock);
        chain->depth = curr->lockdep_depth + 1 - i;
+
+       BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
+       BUILD_BUG_ON((1UL << 6)  <= ARRAY_SIZE(curr->held_locks));
+       BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
+
        if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
                chain->base = nr_chain_hlocks;
-               nr_chain_hlocks += chain->depth;
                for (j = 0; j < chain->depth - 1; j++, i++) {
                        int lock_id = curr->held_locks[i].class_idx - 1;
                        chain_hlocks[chain->base + j] = lock_id;
                }
                chain_hlocks[chain->base + j] = class - lock_classes;
        }
+
+       if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
+               nr_chain_hlocks += chain->depth;
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+       /*
+        * Important for check_no_collision().
+        */
+       if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
+               if (debug_locks_off_graph_unlock())
+                       return 0;
+
+               print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
+               dump_stack();
+               return 0;
+       }
+#endif
+
        hlist_add_head_rcu(&chain->entry, hash_head);
        debug_atomic_inc(chain_lookup_misses);
        inc_chains();
@@ -2932,6 +2954,11 @@ static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
        return 1;
 }
 
+static inline unsigned int task_irq_context(struct task_struct *task)
+{
+       return 2 * !!task->hardirq_context + !!task->softirq_context;
+}
+
 static int separate_irq_context(struct task_struct *curr,
                struct held_lock *hlock)
 {
@@ -2940,8 +2967,6 @@ static int separate_irq_context(struct task_struct *curr,
        /*
         * Keep track of points where we cross into an interrupt context:
         */
-       hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
-                               curr->softirq_context;
        if (depth) {
                struct held_lock *prev_hlock;
 
@@ -2973,6 +2998,11 @@ static inline int mark_irqflags(struct task_struct *curr,
        return 1;
 }
 
+static inline unsigned int task_irq_context(struct task_struct *task)
+{
+       return 0;
+}
+
 static inline int separate_irq_context(struct task_struct *curr,
                struct held_lock *hlock)
 {
@@ -3241,6 +3271,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
        hlock->acquire_ip = ip;
        hlock->instance = lock;
        hlock->nest_lock = nest_lock;
+       hlock->irq_context = task_irq_context(curr);
        hlock->trylock = trylock;
        hlock->read = read;
        hlock->check = check;

diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index dbb61a3025484b4d38bd090bd5923c21a3960ced..a0f61effad25cf0fa2d1dd27557dccd4a3f3ffc5 100644 (file)
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -141,6 +141,8 @@ static int lc_show(struct seq_file *m, void *v)
        int i;
 
        if (v == SEQ_START_TOKEN) {
+               if (nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)
+                       seq_printf(m, "(buggered) ");
                seq_printf(m, "all lock chains:\n");
                return 0;
        }