perf/core: Remove invalid warning from list_update_cgroup_even()t

8fc31ce8 · David Carrillo-Cisneros <[email protected]> · 2016-12-04 00:46:17 -08:00

The warning introduced in commit:

  864c2357ca89 ("perf/core: Do not set cpuctx->cgrp for unscheduled cgroups")

assumed that a cgroup switch always precedes list_del_event. This is
not the case. Remove warning.

Make sure that cpuctx->cgrp is NULL until a cgroup event is sched in
or ctx->nr_cgroups == 0.

Signed-off-by: David Carrillo-Cisneros <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: Nilay Vaish <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ravi V Shankar <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vegard Nossum <[email protected]>
Cc: Vikas Shivappa <[email protected]>
Cc: Vince Weaver <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Commit: 8fc31ce8896fc3cea1d79688c8ff950ad4e73afe
Parents: 7f612a7f

Changes

1 files changed · +8 −11

File	Status	Add	Del	Content
kernel/events/core.c	modified	+8	−11	View file

kernel/events/core.c

View file

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6ee1feb..02c8421 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -903,17 +903,14 @@ list_update_cgroup_event(struct perf_event *event,
 	 */
 	cpuctx = __get_cpu_context(ctx);
 
-	/* Only set/clear cpuctx->cgrp if current task uses event->cgrp. */
-	if (perf_cgroup_from_task(current, ctx) != event->cgrp) {
-		/*
-		 * We are removing the last cpu event in this context.
-		 * If that event is not active in this cpu, cpuctx->cgrp
-		 * should've been cleared by perf_cgroup_switch.
-		 */
-		WARN_ON_ONCE(!add && cpuctx->cgrp);
-		return;
-	}
-	cpuctx->cgrp = add ? event->cgrp : NULL;
+	/*
+	 * cpuctx->cgrp is NULL until a cgroup event is sched in or
+	 * ctx->nr_cgroup == 0 .
+	 */
+	if (add && perf_cgroup_from_task(current, ctx) == event->cgrp)
+		cpuctx->cgrp = event->cgrp;
+	else if (!add)
+		cpuctx->cgrp = NULL;
 }
 
 #else /* !CONFIG_CGROUP_PERF */