diff options
author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2011-01-19 11:51:39 (GMT) |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2011-01-21 15:32:42 (GMT) |
commit | 547e9fd7d328af261f184bf66effc5033c886498 (patch) | |
tree | 88c2cbe138029a017769d4465798db181b1c5461 /kernel/perf_event.c | |
parent | 8c8a9b25b5de3f1eeac721cf34f4379e56d5d694 (diff) | |
download | linux-fsl-qoriq-547e9fd7d328af261f184bf66effc5033c886498.tar.xz |
perf: Annotate cpuctx->ctx.mutex to avoid a lockdep splat
Lockdep spotted:
loop_1b_instruc/1899 is trying to acquire lock:
(event_mutex){+.+.+.}, at: [<ffffffff810e1908>] perf_trace_init+0x3b/0x2f7
but task is already holding lock:
(&ctx->mutex){+.+.+.}, at: [<ffffffff810eb45b>] perf_event_init_context+0xc0/0x218
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&ctx->mutex){+.+.+.}:
-> #2 (cpu_hotplug.lock){+.+.+.}:
-> #1 (module_mutex){+.+...}:
-> #0 (event_mutex){+.+.+.}:
But because the deadlock would be cpuhotplug (cpu-event) vs fork
(task-event) it cannot, in fact, happen. We can annotate this by giving the
perf_event_context used for the cpuctx a different lock class from those
used by tasks.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_event.c')
-rw-r--r-- | kernel/perf_event.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 244ca3a..c5fa717 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -5380,6 +5380,8 @@ free_dev: goto out; } +static struct lock_class_key cpuctx_mutex; + int perf_pmu_register(struct pmu *pmu, char *name, int type) { int cpu, ret; @@ -5428,6 +5430,7 @@ skip_type: cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu); __perf_event_init_context(&cpuctx->ctx); + lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex); cpuctx->ctx.type = cpu_context; cpuctx->ctx.pmu = pmu; cpuctx->jiffies_interval = 1; |