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42 lines
1.8 KiB
42 lines
1.8 KiB
commit 487b38e86c08431bc5f48aac72c8d753ee23cb03
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Author: Willy Tarreau <w@1wt.eu>
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Date: Fri Jul 26 15:10:39 2019 +0200
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BUG/MINOR: log: make sure writev() is not interrupted on a file output
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Since 1.9 we support sending logs to various non-blocking outputs like
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stdou/stderr or flies, by using writev() which guarantees that it only
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returns after having written everything or nothing. However the syscall
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may be interrupted while doing so, and this is visible when writing to
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a tty during debug sessions, as some logs occasionally appear interleaved
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if an xterm or SSH connection is not very fast. Performance here is not a
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critical concern, log correctness is. Let's simply take the logger's lock
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around the writev() call to prevent multiple senders from stepping onto
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each other's toes.
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This may be backported to 2.0 and 1.9.
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(cherry picked from commit 9fbcb7e2e9c32659ab11927394fec2e160be2d0b)
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Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
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diff --git a/src/log.c b/src/log.c
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index ef999d13..99f185e4 100644
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--- a/src/log.c
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+++ b/src/log.c
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@@ -1672,8 +1672,15 @@ send:
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iovec[7].iov_len = 1;
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if (logsrv->addr.ss_family == AF_UNSPEC) {
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- /* the target is a direct file descriptor */
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+ /* the target is a direct file descriptor. While writev() guarantees
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+ * to write everything, it doesn't guarantee that it will not be
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+ * interrupted while doing so. This occasionally results in interleaved
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+ * messages when the output is a tty, hence the lock. There's no real
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+ * performance concern here for such type of output.
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+ */
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+ HA_SPIN_LOCK(LOGSRV_LOCK, &logsrv->lock);
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sent = writev(*plogfd, iovec, 8);
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+ HA_SPIN_UNLOCK(LOGSRV_LOCK, &logsrv->lock);
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}
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else {
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msghdr.msg_name = (struct sockaddr *)&logsrv->addr;
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