perf: Really fix event_function_call() locking

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@intel.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9893ba5e98aa292f1526b7cf3685f58dcb7c097a..c6a720f412258079c9fca17f246444bcad9f823a 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -298,8 +298,8 @@ unlock:
 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 @@ again:
        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();
 }
 
 /*