tracing: Allow irq/preempt tracers to be used by instances

The irqsoff, preemptoff and preemptirqsoff tracers can now be used by
instances. But they may only be used by one instance at a time (including
the top level directory). This allows multiple tracers to run while the
irqsoff (and friends) tracer is running simultaneously.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 40aa300d3491bde7110d4fe603294a39609e231e..9bb104f748d0c048f14db4b5ba9ea29535675ce2 100644 (file)
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -597,8 +597,13 @@ static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
        unregister_irqsoff_function(tr, graph);
 }
 
-static void __irqsoff_tracer_init(struct trace_array *tr)
+static bool irqsoff_busy;
+
+static int __irqsoff_tracer_init(struct trace_array *tr)
 {
+       if (irqsoff_busy)
+               return -EBUSY;
+
        save_flags = trace_flags;
 
        /* non overwrite screws up the latency tracers */
@@ -617,6 +622,9 @@ static void __irqsoff_tracer_init(struct trace_array *tr)
        if (start_irqsoff_tracer(tr, (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
                                      is_graph())))
                printk(KERN_ERR "failed to start irqsoff tracer\n");
+
+       irqsoff_busy = true;
+       return 0;
 }
 
 static void irqsoff_tracer_reset(struct trace_array *tr)
@@ -629,6 +637,8 @@ static void irqsoff_tracer_reset(struct trace_array *tr)
        set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
        set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
        ftrace_reset_array_ops(tr);
+
+       irqsoff_busy = false;
 }
 
 static void irqsoff_tracer_start(struct trace_array *tr)
@@ -646,8 +656,7 @@ static int irqsoff_tracer_init(struct trace_array *tr)
 {
        trace_type = TRACER_IRQS_OFF;
 
-       __irqsoff_tracer_init(tr);
-       return 0;
+       return __irqsoff_tracer_init(tr);
 }
 static struct tracer irqsoff_tracer __read_mostly =
 {
@@ -667,6 +676,7 @@ static struct tracer irqsoff_tracer __read_mostly =
 #endif
        .open           = irqsoff_trace_open,
        .close          = irqsoff_trace_close,
+       .allow_instances = true,
        .use_max_tr     = true,
 };
 # define register_irqsoff(trace) register_tracer(&trace)
@@ -679,8 +689,7 @@ static int preemptoff_tracer_init(struct trace_array *tr)
 {
        trace_type = TRACER_PREEMPT_OFF;
 
-       __irqsoff_tracer_init(tr);
-       return 0;
+       return __irqsoff_tracer_init(tr);
 }
 
 static struct tracer preemptoff_tracer __read_mostly =
@@ -701,6 +710,7 @@ static struct tracer preemptoff_tracer __read_mostly =
 #endif
        .open           = irqsoff_trace_open,
        .close          = irqsoff_trace_close,
+       .allow_instances = true,
        .use_max_tr     = true,
 };
 # define register_preemptoff(trace) register_tracer(&trace)
@@ -715,8 +725,7 @@ static int preemptirqsoff_tracer_init(struct trace_array *tr)
 {
        trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
 
-       __irqsoff_tracer_init(tr);
-       return 0;
+       return __irqsoff_tracer_init(tr);
 }
 
 static struct tracer preemptirqsoff_tracer __read_mostly =
@@ -737,6 +746,7 @@ static struct tracer preemptirqsoff_tracer __read_mostly =
 #endif
        .open           = irqsoff_trace_open,
        .close          = irqsoff_trace_close,
+       .allow_instances = true,
        .use_max_tr     = true,
 };