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Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code

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On Sun, 2016-02-07 at 22:24 +0000, Rainer Weikusat wrote:
> Rainer Weikusat <rw@doppelsaurus.mobileactivedefense.com> writes:
> 
> [...]
> 
> > The start uses that to record an error which might need to be
> > reported, the return statement uses it to indicate that an error has
> > occurred. Hence, some kind of in-between translation must occur.  The
> > mutex_lock_interruptible happened to do that but that was never it's
> > intended purpose.
> 
> Additional information: The 'trick' of using recvmsg w/o a receive
> buffer in order to retrieve control messages in fact wouldn't have
> worked with the unix_stream_recvmsg prior to introduction of the
> interruptible lock as that (judging from the git source) would have
> triggered all the same issues,
> 
> 	- -EOPNOTSUP if a msg was available
> 
>         - -EAGAIN if the code had to wait
> 
>         - not receiving the creds if the -EAGAIN hadn't happened because
>           of the continue (that's the other patch)
> 
> IOW, that's a feature inadvertendly added by an otherwise useless code
> change (mea culpa).

This is exactly the needed information for stable teams.

Goal is here is not to blame someone (you, me ... it does not matter) ,
but give to stable teams the point the problem showed up.

See the 'Fixes' tag as a time saver for people like me.

It is incredibly useful when hutting bugs, because each commit can
easily point to the 'bug origin'.

Having spent time lately in af_unix code insanity, I really can tell.

At the time someone fixes a bug, he/she has a clear view of what is
happening, but months later, he/she often has to start again the commits
analysis.

Thanks a lot.

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[V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream  receive code Joseph Salisbury <joseph.salisbury@canonical.com> - 2016-02-05 20:00 +0100
  Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-05 21:00 +0100
    Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in  stream receive code Joseph Salisbury <joseph.salisbury@canonical.com> - 2016-02-05 21:10 +0100
      Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-05 22:20 +0100
        Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-05 23:10 +0100
  Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-05 22:50 +0100
    Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in  stream receive code Eric Dumazet <eric.dumazet@gmail.com> - 2016-02-06 00:10 +0100
      Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-07 19:50 +0100
        Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-07 21:40 +0100
        Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-07 23:30 +0100
          Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in  stream receive code Eric Dumazet <eric.dumazet@gmail.com> - 2016-02-08 04:40 +0100
  [PATCH] af_unix: Don't set err in unix_stream_read_generic unless there was an error Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-05 23:40 +0100
    Re: [PATCH] af_unix: Don't set err in unix_stream_read_generic unless there was an error Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-07 20:30 +0100
      [PATCH] af_unix: Don't set err in unix_stream_read_generic unless there was an error Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-08 16:40 +0100
        Re: [PATCH] af_unix: Don't set err in unix_stream_read_generic unless there was an error Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-08 19:10 +0100
          [PATCH] af_unix: Don't set err in unix_stream_read_generic unless there was an error Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-08 19:50 +0100
        Re: [PATCH] af_unix: Don't set err in unix_stream_read_generic unless  there was an error Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2016-02-08 19:40 +0100

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