From: Pedro Alves <palves@redhat.com>
To: Don Breazeal <donb@codesourcery.com>, gdb-patches@sourceware.org
Subject: Re: [PATCH 2/3] PR remote/19496, interrupted syscall in forking-threads-plus-bkpt
Date: Mon, 01 Feb 2016 19:38:00 -0000 [thread overview]
Message-ID: <56AFB427.2070909@redhat.com> (raw)
In-Reply-To: <1453942111-1215-3-git-send-email-donb@codesourcery.com>
On 01/28/2016 12:48 AM, Don Breazeal wrote:
> This patch addresses "fork:Interrupted system call" (or wait:) failures
> in gdb.threads/forking-threads-plus-breakpoint.exp.
>
> The test program spawns ten threads, each of which do ten fork/waitpid
> sequences. The cause of the problem was that when one of the fork
> children exited before the corresponding fork parent could initiate its
> waitpid for that child, a SIGCHLD was delivered and interrupted a fork
> or waitpid in another thread.
>
> The fix was to wrap the system calls in a loop to retry the call if
> it was interrupted, like:
>
> do
> {
> pid = fork ();
> }
> while (pid == -1 && errno == EINTR);
>
> Since this is a Linux-only test I figure it is OK to use errno and EINTR.
>
> Tested on Nios II Linux target with x86 Linux host.
I'd prefer to avoid this if possible. These loops potentially hide
bugs like ERESTARTSYS escaping out of a syscall and mishandling of
signals. See bc9540e842eb5639ca59cb133adef211d252843c for example:
https://sourceware.org/ml/gdb-patches/2015-02/msg00654.html
How about setting SIGCHLD to SIG_IGN, or making SIGCHLD be SA_RESTART?
Thanks,
Pedro Alves
next prev parent reply other threads:[~2016-02-01 19:38 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 0:48 [PATCH 0/3] PR remote/19496, remote fork failures Don Breazeal
2016-01-28 0:48 ` [PATCH 1/3] PR remote/19496, internal err forking-threads-plus-bkpt Don Breazeal
2016-02-01 19:26 ` [pushed] Test gdb.threads/forking-threads-plus-breakpoint.exp with, displaced stepping off (Re: [PATCH 1/3] PR remote/19496, internal err forking-threads-plus-bkpt) Pedro Alves
2016-02-01 20:38 ` [PATCH 1/3] PR remote/19496, internal err forking-threads-plus-bkpt Pedro Alves
2016-02-11 0:26 ` [PATCH v2 " Don Breazeal
2016-02-12 20:15 ` Pedro Alves
2016-02-16 17:21 ` Don Breazeal
2016-01-28 0:48 ` [PATCH 2/3] PR remote/19496, interrupted syscall in forking-threads-plus-bkpt Don Breazeal
2016-02-01 19:38 ` Pedro Alves [this message]
2016-01-28 0:48 ` [PATCH 3/3] PR remote/19496, timeout " Don Breazeal
2016-02-01 12:05 ` Pedro Alves
2016-02-01 19:29 ` Don Breazeal
2016-02-01 20:09 ` Pedro Alves
2016-02-11 0:28 ` [PATCH v2 " Don Breazeal
2016-02-25 17:29 ` [PING]Re: " Don Breazeal
2016-03-03 18:20 ` [PING] " Don Breazeal
2016-03-14 21:30 ` Don Breazeal
2016-03-15 15:30 ` Pedro Alves
2016-03-16 17:29 ` Don Breazeal
2016-03-16 22:51 ` Don Breazeal
2016-03-17 10:38 ` Pedro Alves
2016-02-11 0:28 ` [PATCH v2 2/3] PR remote/19496, interrupted syscall " Don Breazeal
2016-02-25 17:28 ` Don Breazeal
2016-03-03 18:19 ` [PING] " Don Breazeal
2016-03-14 21:29 ` Don Breazeal
2016-03-15 12:55 ` Pedro Alves
2016-03-16 18:26 ` Don Breazeal
2016-03-16 18:33 ` Pedro Alves
2016-03-16 22:18 ` Don Breazeal
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