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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Chris Mason <clm@fb.com>, Josef Bacik <jbacik@fb.com>,
	David Sterba <dsterba@suse.com>
Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
	tglx@linutronix.de,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH 2/2] btrfs: swap free() and trace point in run_ordered_work()
Date: Wed, 14 Dec 2016 15:05:30 +0100	[thread overview]
Message-ID: <20161214140530.6534-2-bigeasy@linutronix.de> (raw)
In-Reply-To: <20161214140530.6534-1-bigeasy@linutronix.de>

The previous patch removed a trace point due to a use after free problem
with tracing enabled. While looking at the backtrace it took me a while
to find the right spot. While doing so I noticed that this trace point
could be used after one of two clean-up functions were invoked:
- run_one_async_free()
- async_cow_free()

Both of them free the `work' item so a later use in the tracepoint is
not possible.
This patch swaps the order so we first have the trace point and then
free the struct.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 fs/btrfs/async-thread.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index d0dfc3d2e199..6f4631bf74f8 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -288,8 +288,8 @@ static void run_ordered_work(struct __btrfs_workqueue *=
wq)
 		 * we don't want to call the ordered free functions
 		 * with the lock held though
 		 */
-		work->ordered_free(work);
 		trace_btrfs_all_work_done(work);
+		work->ordered_free(work);
 	}
 	spin_unlock_irqrestore(lock, flags);
 }
--=20
2.11.0


WARNING: multiple messages have this Message-ID (diff)
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Chris Mason <clm@fb.com>, Josef Bacik <jbacik@fb.com>,
	David Sterba <dsterba@suse.com>
Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
	tglx@linutronix.de,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH 2/2] btrfs: swap free() and trace point in run_ordered_work()
Date: Wed, 14 Dec 2016 15:05:30 +0100	[thread overview]
Message-ID: <20161214140530.6534-2-bigeasy@linutronix.de> (raw)
In-Reply-To: <20161214140530.6534-1-bigeasy@linutronix.de>

The previous patch removed a trace point due to a use after free problem
with tracing enabled. While looking at the backtrace it took me a while
to find the right spot. While doing so I noticed that this trace point
could be used after one of two clean-up functions were invoked:
- run_one_async_free()
- async_cow_free()

Both of them free the `work' item so a later use in the tracepoint is
not possible.
This patch swaps the order so we first have the trace point and then
free the struct.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 fs/btrfs/async-thread.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index d0dfc3d2e199..6f4631bf74f8 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -288,8 +288,8 @@ static void run_ordered_work(struct __btrfs_workqueue *wq)
 		 * we don't want to call the ordered free functions
 		 * with the lock held though
 		 */
-		work->ordered_free(work);
 		trace_btrfs_all_work_done(work);
+		work->ordered_free(work);
 	}
 	spin_unlock_irqrestore(lock, flags);
 }
-- 
2.11.0

  reply	other threads:[~2016-12-14 14:05 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-14 14:05 [PATCH 1/2] btrfs: drop trace_btrfs_all_work_done() from normal_work_helper() Sebastian Andrzej Siewior
2016-12-14 14:05 ` Sebastian Andrzej Siewior
2016-12-14 14:05 ` Sebastian Andrzej Siewior [this message]
2016-12-14 14:05   ` [PATCH 2/2] btrfs: swap free() and trace point in run_ordered_work() Sebastian Andrzej Siewior
2016-12-14 14:08   ` [RFC] btrfs: lockdep says "possible recursive locking detected" in btrfs_clear_lock_blocking_rw() Sebastian Andrzej Siewior
2016-12-20 17:26 ` [PATCH 1/2] btrfs: drop trace_btrfs_all_work_done() from normal_work_helper() David Sterba
2016-12-21  0:33   ` Qu Wenruo
2016-12-21  8:28     ` Sebastian Andrzej Siewior
2016-12-21  8:45       ` Qu Wenruo
2016-12-21  8:55         ` Sebastian Andrzej Siewior
2016-12-21 14:08         ` David Sterba

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