Re: [PATCH 09/11] net: Clean up sk_wait_event() vs might_sleep()

Peter Zijlstra
2014-09-24T08:36:47Z

On Wed, Sep 24, 2014 at 10:18:54AM +0200, Peter Zijlstra wrote:
> 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 fixup_sleep(); which goes away on !DEBUG builds.
>
> Cc: netdev@vger.kernel.org
> Cc: David Miller <davem@davemloft.net>
> Reported-by: Ilya Dryomov <ilya.dryomov@inktank.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Dave, FYI this patch relies on a previous one that introduces the
fixup_sleep()

lkml.kernel.org/r/20140924082242.186408915@infradead.org

If you're ok with things, I'll merge this one along with the rest of
things.

> ---
> include/net/sock.h | 1 +
> 1 file changed, 1 insertion(+)
>
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -902,6 +902,7 @@ static inline void sock_rps_reset_rxhash
> if (!__rc) { \
> *(__timeo) = schedule_timeout(*(__timeo)); \
> } \
> + fixup_sleep(); \
> lock_sock(__sk); \
> __rc = __condition; \
> __rc; \
>
>