linux-kernel - Re: net: BUG still has locks held in unix_stream_splice

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Date:   Mon, 10 Oct 2016 03:46:07 +0100
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     David Miller <davem@...emloft.net>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        Eric Dumazet <edumazet@...gle.com>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: net: BUG still has locks held in unix_stream_splice_read

On Sun, Oct 09, 2016 at 12:06:14PM +0200, Dmitry Vyukov wrote:
> I suspect this is:
> 
> commit 25869262ef7af24ccde988867ac3eb1c3d4b88d4
> Author: Al Viro <viro@...iv.linux.org.uk>
> Date:   Sat Sep 17 21:02:10 2016 -0400
>     skb_splice_bits(): get rid of callback
>     since pipe_lock is the outermost now, we don't need to drop/regain
>     socket locks around the call of splice_to_pipe() from skb_splice_bits(),
>     which kills the need to have a socket-specific callback; we can just
>     call splice_to_pipe() and be done with that.

Unlikely, since that particular commit removes unlocking/relocking ->iolock
around the call of splice_to_pipe().  Original would've retaken the same
lock on the way out; it's not as if we could leave the syscall there.

It might be splice-related, but I don't believe that you've got the right
commit here.