Rainer Weikusat <rw@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> 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).
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