From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: X-Spam-Status: No, score=-3.9 required=3.0 tests=ALL_TRUSTED,AWL,BAYES_00 shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from localhost (dcvr.yhbt.net [127.0.0.1]) by dcvr.yhbt.net (Postfix) with ESMTP id 37BB21F4BD for ; Tue, 1 Oct 2019 23:18:02 +0000 (UTC) From: Eric Wong To: meta@public-inbox.org Subject: [PATCH] listener: warn on some accept()/accept4() errors Date: Tue, 1 Oct 2019 23:18:02 +0000 Message-Id: <20191001231802.660-1-e@80x24.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit List-Id: We need to warn when hitting file or socket memory limits or misconfigurations which clear O_NONBLOCK to make it easier to diagnose configuration problems. We'll also warn on some other errors in case bugs creep in... --- lib/PublicInbox/Listener.pm | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/lib/PublicInbox/Listener.pm b/lib/PublicInbox/Listener.pm index f6a5da69..821c3458 100644 --- a/lib/PublicInbox/Listener.pm +++ b/lib/PublicInbox/Listener.pm @@ -10,6 +10,13 @@ use Socket qw(SOL_SOCKET SO_KEEPALIVE IPPROTO_TCP TCP_NODELAY); use fields qw(post_accept); require IO::Handle; use PublicInbox::Syscall qw(EPOLLIN EPOLLEXCLUSIVE EPOLLET); +use Errno qw(EAGAIN ECONNABORTED EPERM); + +# Warn on transient errors, mostly resource limitations. +# EINTR would indicate the failure to set NonBlocking in systemd or similar +my %ERR_WARN = map {; + eval("Errno::$_()") => $_ +} qw(EMFILE ENFILE ENOBUFS ENOMEM EINTR); sub new ($$$) { my ($class, $s, $cb) = @_; @@ -35,6 +42,18 @@ sub event_step { IO::Handle::blocking($c, 0); # no accept4 :< $self->{post_accept}->($c, $addr, $sock); $self->requeue; + } elsif ($! == EAGAIN || $! == ECONNABORTED || $! == EPERM) { + # EAGAIN is common and likely + # ECONNABORTED is common with bad connections + # EPERM happens if firewall rules prevent a connection + # on Linux (and everything that emulates Linux). + # Firewall rules are sometimes intentional, so we don't + # warn on EPERM to avoid being too noisy... + return; + } elsif (my $sym = $ERR_WARN{int($!)}) { + warn "W: accept(): $! ($sym)\n"; + } else { + warn "BUG?: accept(): $!\n"; } } -- EW