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>

diff --git a/include/net/sock.h b/include/net/sock.h
index 7db3db1..e6f235e 100644 (file)
--- 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;                                                   \