unix/dgram: return EAGAIN instead of ENOBUFS when O_NONBLOCK set
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Authored by glebius on Feb 6 2022, 6:33 PM.

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markj
cem
mjg

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network

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rG65572cade35a: unix/dgram: return EAGAIN instead of ENOBUFS when O_NONBLOCK set

Summary

This is behavior what some programs expect and what Linux does. For
example nginx expects EAGAIN when sending messages to /var/run/log,
which it connects to with O_NONBLOCK. Particularly with nginx the
problem is magnified by the fact that a ENOBUFS on send(2) is also
logged, so situation creates a log-bomb - a failed log message
triggers another log message.

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rS FreeBSD src repository - subversion

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Buildable 44310
Build 41198: arc lint + arc unit

Event Timeline

glebius created this revision.Feb 6 2022, 6:33 PM

Herald added a subscriber: imp. · View Herald TranscriptFeb 6 2022, 6:33 PM

glebius requested review of this revision.Feb 6 2022, 6:33 PM

Harbormaster completed remote builds in B44310: Diff 102434.Feb 6 2022, 6:33 PM

I think this is probably ok. EAGAIN is the usual error value for this case. I thought this would break our syslog(3), which explicitly checks for ENOBUFS, but it uses a blocking socket.

This revision is now accepted and ready to land.Feb 6 2022, 10:35 PM

Closed by commit rG65572cade35a: unix/dgram: return EAGAIN instead of ENOBUFS when O_NONBLOCK set (authored by glebius). · Explain WhyFeb 14 2022, 5:23 PM

This revision was automatically updated to reflect the committed changes.

glebius added a commit: rG65572cade35a: unix/dgram: return EAGAIN instead of ENOBUFS when O_NONBLOCK set.

glebius added a reverting change: rG71e70c25c008: Revert "unix/dgram: return EAGAIN instead of ENOBUFS when O_NONBLOCK set".Feb 21 2023, 5:06 PM