[PATCH AUTOSEL 6.10 167/197] perf: Fix event_function_call() locking

From: Sasha Levin
Date: Wed Sep 25 2024 - 09:25:18 EST


From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

[ Upstream commit 558abc7e3f895049faa46b08656be4c60dc6e9fd ]

All the event_function/@func call context already uses perf_ctx_lock()
except for the !ctx->is_active case. Make it all consistent.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Reviewed-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240807115550.138301094@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/events/core.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 081d9692ce747..e18a07de9920a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -263,6 +263,7 @@ static int event_function(void *info)
static void event_function_call(struct perf_event *event, event_f func, void *data)
{
struct perf_event_context *ctx = event->ctx;
+ struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
struct task_struct *task = READ_ONCE(ctx->task); /* verified in event_function */
struct event_function_struct efs = {
.event = event,
@@ -291,22 +292,22 @@ static void event_function_call(struct perf_event *event, event_f func, void *da
if (!task_function_call(task, event_function, &efs))
return;

- raw_spin_lock_irq(&ctx->lock);
+ perf_ctx_lock(cpuctx, ctx);
/*
* Reload the task pointer, it might have been changed by
* a concurrent perf_event_context_sched_out().
*/
task = ctx->task;
if (task == TASK_TOMBSTONE) {
- raw_spin_unlock_irq(&ctx->lock);
+ perf_ctx_unlock(cpuctx, ctx);
return;
}
if (ctx->is_active) {
- raw_spin_unlock_irq(&ctx->lock);
+ perf_ctx_unlock(cpuctx, ctx);
goto again;
}
func(event, NULL, ctx, data);
- raw_spin_unlock_irq(&ctx->lock);
+ perf_ctx_unlock(cpuctx, ctx);
}

/*
--
2.43.0