[PATCH 10/13] perf: Simplify perf_event_context_sched_in()

Peter Zijlstra
2023-11-02T15:33:12Z

kernel/events/core.c | 38 +++++++++++++++-----------------------
1 file changed, 15 insertions(+), 23 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -713,6 +713,9 @@ static void perf_ctx_enable(struct perf_
}
}

+DEFINE_GUARD(perf_ctx_disable, struct perf_event_context *,
+ perf_ctx_disable(_T, false), perf_ctx_enable(_T, false))
+
static void ctx_sched_out(struct perf_event_context *ctx, enum event_type_t event_type);
static void ctx_sched_in(struct perf_event_context *ctx, enum event_type_t event_type);

@@ -3903,31 +3906,27 @@ static void perf_event_context_sched_in(
struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
struct perf_event_context *ctx;

- rcu_read_lock();
+ guard(rcu)();
+
ctx = rcu_dereference(task->perf_event_ctxp);
if (!ctx)
- goto rcu_unlock;
-
- if (cpuctx->task_ctx == ctx) {
- perf_ctx_lock(cpuctx, ctx);
- perf_ctx_disable(ctx, false);
-
- perf_ctx_sched_task_cb(ctx, true);
-
- perf_ctx_enable(ctx, false);
- perf_ctx_unlock(cpuctx, ctx);
- goto rcu_unlock;
- }
+ return;

- perf_ctx_lock(cpuctx, ctx);
+ guard(perf_ctx_lock)(cpuctx, ctx);
/*
* We must check ctx->nr_events while holding ctx->lock, such
* that we serialize against perf_install_in_context().
*/
if (!ctx->nr_events)
- goto unlock;
+ return;
+
+ guard(perf_ctx_disable)(ctx);
+
+ if (cpuctx->task_ctx == ctx) {
+ perf_ctx_sched_task_cb(ctx, true);
+ return;
+ }

- perf_ctx_disable(ctx, false);
/*
* We want to keep the following priority order:
* cpu pinned (that don't need to move), task pinned,
@@ -3947,13 +3946,6 @@ static void perf_event_context_sched_in(

if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree))
perf_ctx_enable(&cpuctx->ctx, false);
-
- perf_ctx_enable(ctx, false);
-
-unlock:
- perf_ctx_unlock(cpuctx, ctx);
-rcu_unlock:
- rcu_read_unlock();
}

/*