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From: Eric Wong <e@80x24.org>
To: meta@public-inbox.org
Subject: [PATCH 4/4] DS: epoll: fix misordered EPOLL_CTL_DEL call
Date: Wed,  8 May 2019 19:18:56 +0000	[thread overview]
Message-ID: <20190508191856.20485-5-e@80x24.org> (raw)
In-Reply-To: <20190508191856.20485-1-e@80x24.org>

Any operations on an fd after POSIX::close() are invalid, so
epoll_ctl will fail.  Worse off, in a multi-threaded Perl, the
fd may be reused by another thread and EPOLL_CTL_DEL can hit the
wrong file description as a result.

cf. https://rt.cpan.org/Ticket/Display.html?id=129487
---
 lib/PublicInbox/DS.pm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/PublicInbox/DS.pm b/lib/PublicInbox/DS.pm
index c03bd5d..779215c 100644
--- a/lib/PublicInbox/DS.pm
+++ b/lib/PublicInbox/DS.pm
@@ -333,8 +333,8 @@ sub EpollEventLoop {
                 } else {
                     my $fd = $ev->[0];
                     warn "epoll() returned fd $fd w/ state $state for which we have no mapping.  removing.\n";
-                    POSIX::close($fd);
                     epoll_ctl($Epoll, EPOLL_CTL_DEL, $fd, 0);
+                    POSIX::close($fd);
                 }
                 next;
             }
-- 
EW


      parent reply	other threads:[~2019-05-08 19:18 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-05  0:52 [PATCH 0/4] bundle Danga::Socket and Sys::Syscall Eric Wong
2019-05-05  0:52 ` [PATCH 1/4] " Eric Wong
2019-05-05  4:56   ` [PATCH 5/4] DS: workaround IO::Kqueue EINTR (mis-)handling Eric Wong
2019-05-08  9:07   ` [PATCH 6/4] DS: handle EINTR in IO::Poll path, too Eric Wong
2019-05-05  0:52 ` [PATCH 2/4] listener: use EPOLLEXCLUSIVE for listen sockets Eric Wong
2019-05-05  0:52 ` [PATCH 3/4] DS: remove unused fields and functions Eric Wong
2019-05-05  0:52 ` [PATCH 4/4] DS: drop profiling support Eric Wong
2019-05-08 19:18 ` [PATCH 0/4] Danga::Socket bundling cleanups Eric Wong
2019-05-08 19:18   ` [PATCH 1/4] build: do not manify DS and Syscall pods Eric Wong
2019-05-08 19:18   ` [PATCH 2/4] syscall: drop readahead wrapper Eric Wong
2019-05-08 19:18   ` [PATCH 3/4] DS: drop unused "_undef" sub Eric Wong
2019-05-08 19:18   ` Eric Wong [this message]

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