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From f7abffec751e454d119df273dc6e49e5f7106078 Mon Sep 17 00:00:00 2001
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From: Sage Weil <sage@redhat.com>
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Date: Wed, 7 Dec 2016 18:25:55 -0600
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Subject: [PATCH] msg/simple/Pipe: avoid returning 0 on poll timeout
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If poll times out it will return 0 (no data to read on socket). In
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165e5abdbf6311974d4001e43982b83d06f9e0cc we changed tcp_read_wait from
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returning -1 to returning -errno, which means we return 0 instead of -1
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in this case.
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This makes tcp_read() get into an infinite loop by repeatedly trying to
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read from the socket and getting EAGAIN.
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Fix by explicitly checking for a 0 return from poll(2) and returning
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EAGAIN in that case.
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Fixes: http://tracker.ceph.com/issues/18184
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Signed-off-by: Sage Weil <sage@redhat.com>
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(cherry picked from commit 6c3d015c6854a12cda40673848813d968ff6afae)
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---
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src/msg/simple/Pipe.cc | 5 ++++-
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1 file changed, 4 insertions(+), 1 deletion(-)
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diff --git a/src/msg/simple/Pipe.cc b/src/msg/simple/Pipe.cc
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index 80b948d..cfb1986 100644
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--- a/src/msg/simple/Pipe.cc
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+++ b/src/msg/simple/Pipe.cc
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@@ -2500,8 +2500,11 @@ int Pipe::tcp_read_wait()
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if (has_pending_data())
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return 0;
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- if (poll(&pfd, 1, msgr->timeout) <= 0)
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+ int r = poll(&pfd, 1, msgr->timeout);
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+ if (r < 0)
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return -errno;
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+ if (r == 0)
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+ return -EAGAIN;
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evmask = POLLERR | POLLHUP | POLLNVAL;
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#if defined(__linux__)
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--
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2.7.4
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