[tip:perf/core] perf: Simplify perf_event_exit_task_context()

From: tip-bot for Peter Zijlstra
Date: Thu May 08 2014 - 06:46:22 EST


Commit-ID: 3a497f48637e2aac17eabb84a17f8ac5216028fc
Gitweb: http://git.kernel.org/tip/3a497f48637e2aac17eabb84a17f8ac5216028fc
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Mon, 5 May 2014 12:42:29 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 7 May 2014 13:44:19 +0200

perf: Simplify perf_event_exit_task_context()

Instead of jumping through hoops to make sure to find (and exit) each
event, do it the simple straight fwd way.

Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-tij931199thfkys8vbnokdpf@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/events/core.c | 17 +----------------
1 file changed, 1 insertion(+), 16 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 83505a3..7ab734f 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7485,24 +7485,9 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
*/
mutex_lock(&child_ctx->mutex);

-again:
- list_for_each_entry_safe(child_event, tmp, &child_ctx->pinned_groups,
- group_entry)
- __perf_event_exit_task(child_event, child_ctx, child);
-
- list_for_each_entry_safe(child_event, tmp, &child_ctx->flexible_groups,
- group_entry)
+ list_for_each_entry_rcu(child_event, &child_ctx->event_list, event_entry)
__perf_event_exit_task(child_event, child_ctx, child);

- /*
- * If the last event was a group event, it will have appended all
- * its siblings to the list, but we obtained 'tmp' before that which
- * will still point to the list head terminating the iteration.
- */
- if (!list_empty(&child_ctx->pinned_groups) ||
- !list_empty(&child_ctx->flexible_groups))
- goto again;
-
mutex_unlock(&child_ctx->mutex);

put_ctx(child_ctx);
--
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