linux-kernel - [tip:perfcounters/core] perf_counter: fix up counter free paths

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Date:	Fri, 20 Mar 2009 10:25:08 GMT
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, paulus@...ba.org, hpa@...or.com,
	mingo@...hat.com, rostedt@...dmis.org, a.p.zijlstra@...llo.nl,
	tglx@...utronix.de, mingo@...e.hu
Subject: [tip:perfcounters/core] perf_counter: fix up counter free paths

Commit-ID:  789ce7d327a1548779d8b3ca15f244e17c899fe8
Gitweb:     http://git.kernel.org/tip/789ce7d327a1548779d8b3ca15f244e17c899fe8
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Thu, 19 Mar 2009 20:26:16 +0100
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 20 Mar 2009 11:15:12 +0100

perf_counter: fix up counter free paths

Impact: fix crash during perfcounters use

I found another counter free path, create a free_counter() call to
accomodate generic tear-down.

Fixes an RCU bug.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
LKML-Reference: <20090319194233.652078652@...llo.nl>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 kernel/perf_counter.c |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 99d5930..97f891f 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1150,6 +1150,11 @@ static void free_counter_rcu(struct rcu_head *head)
 	kfree(counter);
 }
 
+static void free_counter(struct perf_counter *counter)
+{
+	call_rcu(&counter->rcu_head, free_counter_rcu);
+}
+
 /*
  * Called when the last reference to the file is gone.
  */
@@ -1168,7 +1173,7 @@ static int perf_release(struct inode *inode, struct file *file)
 	mutex_unlock(&counter->mutex);
 	mutex_unlock(&ctx->mutex);
 
-	call_rcu(&counter->rcu_head, free_counter_rcu);
+	free_counter(counter);
 	put_context(ctx);
 
 	return 0;
@@ -2128,10 +2133,10 @@ __perf_counter_exit_task(struct task_struct *child,
 					 list_entry) {
 			if (sub->parent) {
 				sync_child_counter(sub, sub->parent);
-				kfree(sub);
+				free_counter(sub);
 			}
 		}
-		kfree(child_counter);
+		free_counter(child_counter);
 	}
 }
 
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