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Re: [PATCH] af_unix: Revert 'lock_interruptible' in stream receive code

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Hannes Frederic Sowa <hannes@stressinduktion.org> writes:
> On 16.12.2015 21:09, Rainer Weikusat wrote:
>> With b3ca9b02b00704053a38bfe4c31dbbb9c13595d0, the AF_UNIX SOCK_STREAM
>> receive code was changed from using mutex_lock(&u->readlock) to
>> mutex_lock_interruptible(&u->readlock) to prevent signals from being
>> delayed for an indefinite time if a thread sleeping on the mutex
>> happened to be selected for handling the signal. But this was never a
>> problem with the stream receive code (as opposed to its datagram
>> counterpart) as that never went to sleep waiting for new messages with the
>> mutex held and thus, wouldn't cause secondary readers to block on the
>> mutex waiting for the sleeping primary reader. As the interruptible
>> locking makes the code more complicated in exchange for no benefit,
>> change it back to using mutex_lock.
>> 
>> Signed-off-by: Rainer Weikusat <rweikusat@mobileactivedefense.com>
>> ---
>> 
>> Considering that the datagram receive routine also doesn't go the sleep
>> with the mutex held anymore, the 37ab4fa7844a044dc21fde45e2a0fc2f3c3b6490
>> change to unix_autobind is now similarly purposeless.
>
> I wouldn't do this conversion, yet. There is still a deadlock lingering
> around which should be solved earlier:
>
> http://lists.openwall.net/netdev/2015/11/10/4
>
> Unfortunately I haven't found a good way how to solve it, yet.

Judging from the link, that's not related to the stream receive code.
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[PATCH] af_unix: Revert 'lock_interruptible' in stream receive code Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-12-16 21:10 +0100
  Re: [PATCH] af_unix: Revert 'lock_interruptible' in stream receive  code Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-12-17 10:30 +0100
    Re: [PATCH] af_unix: Revert 'lock_interruptible' in stream receive code Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-12-17 16:30 +0100
      Re: [PATCH] af_unix: Revert 'lock_interruptible' in stream receive  code Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-12-17 16:50 +0100
    Re: [PATCH] af_unix: Revert 'lock_interruptible' in stream receive code Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-12-18 00:30 +0100
      splice-bind deadlock (was: [PATCH] af_unix: Revert 'lock_interruptible' in stream receive code) Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2015-12-18 17:10 +0100
  Re: [PATCH] af_unix: Revert 'lock_interruptible' in stream receive  code David Miller <davem@davemloft.net> - 2015-12-17 21:40 +0100

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