On Tue, Aug 13, 2024 at 11:28:54AM -0700, Namhyung Kim wrote:
Duh, yeah.
> ---
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 9893ba5e98aa..85204c2376fa 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -298,13 +298,14 @@ 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 perf_cpu_context *cpuctx;
> struct task_struct *task = READ_ONCE(ctx->task); /* verified in event_function */
> struct event_function_struct efs = {
> .event = event,
> .func = func,
> .data = data,
> };
> + unsigned long flags;
>
> if (!event->parent) {
> /*
> @@ -327,22 +328,27 @@ static void event_function_call(struct perf_event *event, event_f func, void *da
> if (!task_function_call(task, event_function, &efs))
> return;
>
> + local_irq_save(flags);
This can just be local_irq_disable() though, seeing how the fingered
commit replaced raw_spin_lock_irq().
I'll queue the below...
---
Subject: perf: Really fix event_function_call() locking
From: Namhyung Kim <namhyung@xxxxxxxxxx>
Date: Tue Aug 13 22:55:11 CEST 2024
Commit 558abc7e3f89 ("perf: Fix event_function_call() locking") lost
IRQ disabling by mistake.
Fixes: 558abc7e3f89 ("perf: Fix event_function_call() locking")
Reported-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
kernel/events/core.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -298,8 +298,8 @@ 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 perf_cpu_context *cpuctx;
struct event_function_struct efs = {
.event = event,
.func = func,
@@ -327,22 +327,25 @@ static void event_function_call(struct p
if (!task_function_call(task, event_function, &efs))
return;
+ local_irq_disable();
+ cpuctx = this_cpu_ptr(&perf_cpu_context);
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) {
- perf_ctx_unlock(cpuctx, ctx);
- return;
- }
+ if (task == TASK_TOMBSTONE)
+ goto unlock;
if (ctx->is_active) {
perf_ctx_unlock(cpuctx, ctx);
+ local_irq_enable();
goto again;
}
func(event, NULL, ctx, data);
+unlock:
perf_ctx_unlock(cpuctx, ctx);
+ local_irq_enable();
}
/*
|