[PATCH 12/13] perf: Simplify perf_event_*_on_exec()

Peter Zijlstra
2023-11-02T15:33:21Z

kernel/events/core.c | 88 +++++++++++++++++++++++----------------------------
1 file changed, 40 insertions(+), 48 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4318,39 +4318,36 @@ static void perf_event_enable_on_exec(st
enum event_type_t event_type = 0;
struct perf_cpu_context *cpuctx;
struct perf_event *event;
- unsigned long flags;
int enabled = 0;

- local_irq_save(flags);
- if (WARN_ON_ONCE(current->perf_event_ctxp != ctx))
- goto out;
-
- if (!ctx->nr_events)
- goto out;
-
- cpuctx = this_cpu_ptr(&perf_cpu_context);
- perf_ctx_lock(cpuctx, ctx);
- ctx_sched_out(ctx, EVENT_TIME);
-
- list_for_each_entry(event, &ctx->event_list, event_entry) {
- enabled |= event_enable_on_exec(event, ctx);
- event_type |= get_event_type(event);
+ scoped_guard (irqsave) {
+ if (WARN_ON_ONCE(current->perf_event_ctxp != ctx))
+ return;
+
+ if (!ctx->nr_events)
+ return;
+
+ cpuctx = this_cpu_ptr(&perf_cpu_context);
+ guard(perf_ctx_lock)(cpuctx, ctx);
+
+ ctx_sched_out(ctx, EVENT_TIME);
+
+ list_for_each_entry(event, &ctx->event_list, event_entry) {
+ enabled |= event_enable_on_exec(event, ctx);
+ event_type |= get_event_type(event);
+ }
+
+ /*
+ * Unclone and reschedule this context if we enabled any event.
+ */
+ if (enabled) {
+ clone_ctx = unclone_ctx(ctx);
+ ctx_resched(cpuctx, ctx, event_type);
+ } else {
+ ctx_sched_in(ctx, EVENT_TIME);
+ }
}

- /*
- * Unclone and reschedule this context if we enabled any event.
- */
- if (enabled) {
- clone_ctx = unclone_ctx(ctx);
- ctx_resched(cpuctx, ctx, event_type);
- } else {
- ctx_sched_in(ctx, EVENT_TIME);
- }
- perf_ctx_unlock(cpuctx, ctx);
-
-out:
- local_irq_restore(flags);
-
if (clone_ctx)
put_ctx(clone_ctx);
}
@@ -4367,34 +4364,29 @@ static void perf_event_remove_on_exec(st
{
struct perf_event_context *clone_ctx = NULL;
struct perf_event *event, *next;
- unsigned long flags;
bool modified = false;

- mutex_lock(&ctx->mutex);
+ scoped_guard (mutex, &ctx->mutex) {
+ if (WARN_ON_ONCE(ctx->task != current))
+ return;

- if (WARN_ON_ONCE(ctx->task != current))
- goto unlock;
+ list_for_each_entry_safe(event, next, &ctx->event_list, event_entry) {
+ if (!event->attr.remove_on_exec)
+ continue;

- list_for_each_entry_safe(event, next, &ctx->event_list, event_entry) {
- if (!event->attr.remove_on_exec)
- continue;
+ if (!is_kernel_event(event))
+ perf_remove_from_owner(event);

- if (!is_kernel_event(event))
- perf_remove_from_owner(event);
+ modified = true;

- modified = true;
+ perf_event_exit_event(event, ctx);
+ }

- perf_event_exit_event(event, ctx);
+ guard(raw_spinlock_irqsave)(&ctx->lock);
+ if (modified)
+ clone_ctx = unclone_ctx(ctx);
}

- raw_spin_lock_irqsave(&ctx->lock, flags);
- if (modified)
- clone_ctx = unclone_ctx(ctx);
- raw_spin_unlock_irqrestore(&ctx->lock, flags);
-
-unlock:
- mutex_unlock(&ctx->mutex);
-
if (clone_ctx)
put_ctx(clone_ctx);
}