[tip:sched/core] sched, net: Clean up sk_wait_event() vs. might_sleep()

tip-bot for Peter Zijlstra
2014-10-28T11:12:35Z

Commit-ID: 26cabd31259ba43f68026ce3f62b78094124333f
Gitweb: http://git.kernel.org/tip/26cabd31259ba43f68026ce3f62b78094124333f
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Wed, 24 Sep 2014 10:18:54 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 Oct 2014 10:56:37 +0100

sched, net: Clean up sk_wait_event() vs. might_sleep()

WARNING: CPU: 1 PID: 1744 at kernel/sched/core.c:7104 __might_sleep+0x58/0x90()
do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff81070e10>] prepare_to_wait+0x50 /0xa0

[<ffffffff8105bc38>] __might_sleep+0x58/0x90
[<ffffffff8148c671>] lock_sock_nested+0x31/0xb0
[<ffffffff81498aaa>] sk_stream_wait_memory+0x18a/0x2d0

Which is a false positive because sk_wait_event() will already have
TASK_RUNNING at that point if it would've gone through
schedule_timeout().

So annotate with sched_annotate_sleep(); which goes away on !DEBUG builds.

Reported-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140924082242.524407432@infradead.org
Cc: David S. Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: netdev@vger.kernel.org
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: oleg@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
include/net/sock.h | 1 +
1 file changed, 1 insertion(+)

diff --git a/include/net/sock.h b/include/net/sock.h
index 7db3db1..e6f235e 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -897,6 +897,7 @@ static inline void sock_rps_reset_rxhash(struct sock *sk)
if (!__rc) { \
*(__timeo) = schedule_timeout(*(__timeo)); \
} \
+ sched_annotate_sleep(); \
lock_sock(__sk); \
__rc = __condition; \
__rc; \