On 08/08/2012 02:59 PM, Peter Feiner wrote:
>>From man poll(2), poll does not set errno=EAGAIN, however it does set
> errno=EINTR. Have libvirt retry on the appropriate errno.
man poll(2) is slightly wrong - according to POSIX, poll may _also_ set
EAGAIN when "The allocation of internal data structures failed but a
subsequent request may succeed." But you are correct that poll()
interrupted by a signal must be EINTR.
I went looking (git grep -A3 '\bpoll *([a-zA-Z]'), and some of our code
already checks for _both_ EAGAIN and EINTR, so I'd feel safer updating
ALL the code to check for both instead of one.
>
> Under heavy load, a program of mine kept getting libvirt errors 'poll on
> socket
> failed: Interrupted system call'. The signals were SIGCHLD from processes
> forked
> by threads unrelated to those using libvirt.
>
> diff --git a/src/rpc/virnetclient.c b/src/rpc/virnetclient.c
> index 2530ffa..f2a6922 100644
> --- a/src/rpc/virnetclient.c
> +++ b/src/rpc/virnetclient.c
> @@ -1374,7 +1374,7 @@ static int virNetClientIOEventLoop(virNetClientPtr
> client,
>
> repoll:
> ret = poll(fds, ARRAY_CARDINALITY(fds), timeout);
> - if (ret < 0 && errno == EAGAIN)
> + if (ret < 0 && errno == EINTR)
> goto repoll;
>
> ignore_value(pthread_sigmask(SIG_SETMASK, &oldmask, NULL));
>
I squashed this into your change, and pushed. I also added you to
AUTHORS; let me know if you prefer an alternate spelling of name or email.
diff --git i/src/rpc/virnetclient.c w/src/rpc/virnetclient.c
index 2530ffa..42bdc54 100644
--- i/src/rpc/virnetclient.c
+++ w/src/rpc/virnetclient.c
@@ -1,7 +1,7 @@
/*
* virnetclient.c: generic network RPC client
*
- * Copyright (C) 2006-2011 Red Hat, Inc.
+ * Copyright (C) 2006-2012 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
@@ -651,7 +651,7 @@ int virNetClientSetTLSSession(virNetClientPtr client,
repoll:
ret = poll(fds, ARRAY_CARDINALITY(fds), -1);
- if (ret < 0 && errno == EAGAIN)
+ if (ret < 0 && (errno == EAGAIN || errno == EINTR))
goto repoll;
ignore_value(pthread_sigmask(SIG_BLOCK, &oldmask, NULL));
@@ -675,7 +675,7 @@ int virNetClientSetTLSSession(virNetClientPtr client,
repoll2:
ret = poll(fds, ARRAY_CARDINALITY(fds), -1);
- if (ret < 0 && errno == EAGAIN)
+ if (ret < 0 && (errno == EAGAIN || errno == EINTR))
goto repoll2;
ignore_value(pthread_sigmask(SIG_BLOCK, &oldmask, NULL));
@@ -1374,7 +1374,7 @@ static int virNetClientIOEventLoop(virNetClientPtr
client,
repoll:
ret = poll(fds, ARRAY_CARDINALITY(fds), timeout);
- if (ret < 0 && errno == EAGAIN)
+ if (ret < 0 && (errno == EAGAIN || errno == EINTR))
goto repoll;
ignore_value(pthread_sigmask(SIG_SETMASK, &oldmask, NULL));
diff --git i/src/util/event_poll.c w/src/util/event_poll.c
index 1bc1d41..0e7d1c1 100644
--- i/src/util/event_poll.c
+++ w/src/util/event_poll.c
@@ -1,7 +1,7 @@
/*
* event.c: event loop for monitoring file handles
*
- * Copyright (C) 2007, 2010-2011 Red Hat, Inc.
+ * Copyright (C) 2007, 2010-2012 Red Hat, Inc.
* Copyright (C) 2007 Daniel P. Berrange
*
* This library is free software; you can redistribute it and/or
@@ -615,7 +615,7 @@ int virEventPollRunOnce(void) {
ret = poll(fds, nfds, timeout);
if (ret < 0) {
EVENT_DEBUG("Poll got error event %d", errno);
- if (errno == EINTR) {
+ if (errno == EINTR || errno == EAGAIN) {
goto retry;
}
virReportSystemError(errno, "%s",
--
Eric Blake eblake@xxxxxxxxxx +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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