From: John Baldwin <jhb@FreeBSD.org>
To: Pedro Alves <pedro@palves.net>, gdb-patches@sourceware.org
Subject: Re: [PATCH 0/4] Introduce scoped_ignore_signal & make it thread safe
Date: Tue, 15 Jun 2021 10:04:45 -0700 [thread overview]
Message-ID: <ad44860f-d842-cf03-a9a6-91299180fe9e@FreeBSD.org> (raw)
In-Reply-To: <20210615111429.1879286-1-pedro@palves.net>
On 6/15/21 4:14 AM, Pedro Alves wrote:
> For the Ctrl-C rework series I posted recently, I stared at code using
> scoped_ignore_sigttou a lot, and it annoyed me that it isn't thread
> safe, because it changes the signal's disposition.
>
> Very recently, we got a new scoped_ignore_sigpipe class modelled on
> scoped_ignore_sigttou, which made me want to fix this before it ever
> becomes a (hard to debug) problem. I mentioned this here:
>
> https://sourceware.org/pipermail/gdb-patches/2021-June/179958.html
I think this looks ok to me. The one difference I can think of when
using sigpromask() instead of SIG_IGN is if the signal might be
sent to another thread instead of masked. However, both SIGPIPE
and SIGTTOU sent in the context of write() should be sent to the
specific thread calling write(). SIGTTOU is a bit funky in that
it gets raised to the entire process group, but in FreeBSD at least
we only raise it if it is not masked for the current thread that
has invoked write(). (If the signal is masked, it isn't raised at
all.)
--
John Baldwin
next prev parent reply other threads:[~2021-06-15 17:04 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 11:14 Pedro Alves
2021-06-15 11:14 ` [PATCH 1/4] Move scoped_ignore_sigttou to gdbsupport/ Pedro Alves
2021-06-15 11:14 ` [PATCH 2/4] Introduce scoped_restore_signal Pedro Alves
2021-06-17 14:57 ` Pedro Alves
2021-06-15 11:14 ` [PATCH 3/4] scoped_ignore_signal: Use sigprocmask+sigtimedwait instead of signal Pedro Alves
2021-06-26 12:35 ` Simon Marchi
2021-06-26 13:41 ` John Baldwin
2021-06-26 19:10 ` Simon Marchi
2021-06-27 14:55 ` Pedro Alves
2021-06-27 19:01 ` Simon Marchi
2021-06-15 11:14 ` [PATCH 4/4] Add a unit test for scoped_ignore_sigpipe Pedro Alves
2021-06-15 22:26 ` Lancelot SIX
2021-06-17 13:00 ` Pedro Alves
2021-06-15 17:04 ` John Baldwin [this message]
2021-06-17 14:38 ` [PATCH 0/4] Introduce scoped_ignore_signal & make it thread safe Pedro Alves
2021-06-17 15:36 ` Pedro Alves
2021-06-17 16:45 ` John Baldwin
2021-06-17 18:44 ` [pushed] Don't call sigtimedwait for scoped_ignore_sigttou Pedro Alves
2021-06-15 20:16 ` [PATCH 0/4] Introduce scoped_ignore_signal & make it thread safe Tom Tromey
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