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Message-ID: <tip-66fff22483d8542dfb4d61a28d21277bbde321e8@git.kernel.org>
Date: Thu, 11 Jun 2009 00:42:49 GMT
From: tip-bot for Peter Zijlstra <a.p.zijlstra@...llo.nl>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, acme@...hat.com, paulus@...ba.org,
hpa@...or.com, mingo@...hat.com, a.p.zijlstra@...llo.nl,
efault@....de, tglx@...utronix.de, mingo@...e.hu
Subject: [tip:perfcounters/core] perf_counter: Annotate exit ctx recursion
Commit-ID: 66fff22483d8542dfb4d61a28d21277bbde321e8
Gitweb: http://git.kernel.org/tip/66fff22483d8542dfb4d61a28d21277bbde321e8
Author: Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Wed, 10 Jun 2009 22:53:37 +0200
Committer: Ingo Molnar <mingo@...e.hu>
CommitDate: Thu, 11 Jun 2009 02:39:01 +0200
perf_counter: Annotate exit ctx recursion
Ever since Paul fixed it to unclone the context before taking the
ctx->lock this became a false positive, annotate it away.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Mike Galbraith <efault@....de>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
kernel/perf_counter.c | 13 ++++++++++++-
1 files changed, 12 insertions(+), 1 deletions(-)
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 51c571e..ae591a1 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -3879,7 +3879,18 @@ void perf_counter_exit_task(struct task_struct *child)
spin_unlock(&child_ctx->lock);
local_irq_restore(flags);
- mutex_lock(&child_ctx->mutex);
+ /*
+ * We can recurse on the same lock type through:
+ *
+ * __perf_counter_exit_task()
+ * sync_child_counter()
+ * fput(parent_counter->filp)
+ * perf_release()
+ * mutex_lock(&ctx->mutex)
+ *
+ * But since its the parent context it won't be the same instance.
+ */
+ mutex_lock_nested(&child_ctx->mutex, SINGLE_DEPTH_NESTING);
again:
list_for_each_entry_safe(child_counter, tmp, &child_ctx->counter_list,
--
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