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perf/core: Fix event_function_local() 

Vincent reported triggering the WARN_ON_ONCE() in event_function_local().

While thinking through cases I noticed that by using event_function()
directly, we miss the inactive case usually handled by
event_function_call().

Therefore construct a blend of event_function_call() and
event_function() that handles the cases relevant to
event_function_local().

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org # 4.5+
Fixes: fae3fde651 ("perf: Collapse and fix event_function_call() users")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-08-16 13:33:26 +02:00 committed by Ingo Molnar
parent 6c4687cc17
commit cca2094605
1 changed files with 48 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
kernel/events/core.c
View File

@ -242,18 +242,6 @@ unlock:
return ret;
}
static void event_function_local(struct perf_event *event, event_f func, void *data)
{
struct event_function_struct efs = {
.event = event,
.func = func,
.data = data,
};
int ret = event_function(&efs);
WARN_ON_ONCE(ret);
}
static void event_function_call(struct perf_event *event, event_f func, void *data)
{
struct perf_event_context *ctx = event->ctx;
@ -303,6 +291,54 @@ again:
raw_spin_unlock_irq(&ctx->lock);
}
/*
* Similar to event_function_call() + event_function(), but hard assumes IRQs
* are already disabled and we're on the right CPU.
*/
static void event_function_local(struct perf_event *event, event_f func, void *data)
{
struct perf_event_context *ctx = event->ctx;
struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
struct task_struct *task = READ_ONCE(ctx->task);
struct perf_event_context *task_ctx = NULL;
WARN_ON_ONCE(!irqs_disabled());
if (task) {
if (task == TASK_TOMBSTONE)
return;
task_ctx = ctx;
}
perf_ctx_lock(cpuctx, task_ctx);
task = ctx->task;
if (task == TASK_TOMBSTONE)
goto unlock;
if (task) {
/*
* We must be either inactive or active and the right task,
* otherwise we're screwed, since we cannot IPI to somewhere
* else.
*/
if (ctx->is_active) {
if (WARN_ON_ONCE(task != current))
goto unlock;
if (WARN_ON_ONCE(cpuctx->task_ctx != ctx))
goto unlock;
}
} else {
WARN_ON_ONCE(&cpuctx->ctx != ctx);
}
func(event, cpuctx, ctx, data);
unlock:
perf_ctx_unlock(cpuctx, task_ctx);
}
#define PERF_FLAG_ALL (PERF_FLAG_FD_NO_GROUP |\
PERF_FLAG_FD_OUTPUT |\
PERF_FLAG_PID_CGROUP |\