| Message ID | m3r3mmdn7g.fsf@sspiff.org |
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Received: (qmail 77060 invoked by alias); 29 Aug 2015 17:23:15 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: <gdb-patches.sourceware.org> List-Unsubscribe: <mailto:gdb-patches-unsubscribe-##L=##H@sourceware.org> List-Subscribe: <mailto:gdb-patches-subscribe@sourceware.org> List-Archive: <http://sourceware.org/ml/gdb-patches/> List-Post: <mailto:gdb-patches@sourceware.org> List-Help: <mailto:gdb-patches-help@sourceware.org>, <http://sourceware.org/ml/#faqs> Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 77050 invoked by uid 89); 29 Aug 2015 17:23:14 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.3 required=5.0 tests=AWL, BAYES_00, FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM, MALFORMED_FREEMAIL, RCVD_IN_DNSWL_LOW, SPF_PASS autolearn=no version=3.3.2 X-HELO: mail-pa0-f54.google.com Received: from mail-pa0-f54.google.com (HELO mail-pa0-f54.google.com) (209.85.220.54) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Sat, 29 Aug 2015 17:23:13 +0000 Received: by pabzx8 with SMTP id zx8so94038181pab.1 for <gdb-patches@sourceware.org>; Sat, 29 Aug 2015 10:23:11 -0700 (PDT) X-Received: by 10.68.250.5 with SMTP id yy5mr25032215pbc.34.1440868991673; Sat, 29 Aug 2015 10:23:11 -0700 (PDT) Received: from seba.sebabeach.org.gmail.com (173-13-178-53-sfba.hfc.comcastbusiness.net. [173.13.178.53]) by smtp.gmail.com with ESMTPSA id j5sm9227231pdi.7.2015.08.29.10.23.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 29 Aug 2015 10:23:11 -0700 (PDT) From: Doug Evans <xdje42@gmail.com> To: gdb-patches@sourceware.org Subject: [RFC] Block all async signals used by gdb when initializing Guile cc: guile-devel@gnu.org Date: Sat, 29 Aug 2015 10:22:11 -0700 Message-ID: <m3r3mmdn7g.fsf@sspiff.org> MIME-Version: 1.0 Content-Type: text/plain X-IsSubscribed: yes |
Commit Message
Doug Evans
Aug. 29, 2015, 5:22 p.m. UTC
Hi. When Guile initializes it will start several GC threads (libgc). It's important that these threads block SIGCHLD (PR 17247). This patch extends this to all async signals used by gdb. One improvement on this patch would be to have event-top.c (or some such) provide a routine that calls sigaddset for each appropriate signal rather than defining the list in guile.c. 2015-08-29 Doug Evans <xdje42@gmail.com> * guile/guile.c (_initialize_guile): Block all asynchronous signals used by gdb when initializing Guile.
Comments
> From: Doug Evans <xdje42@gmail.com> > cc: guile-devel@gnu.org > Date: Sat, 29 Aug 2015 10:22:11 -0700 > > --- a/gdb/guile/guile.c > +++ b/gdb/guile/guile.c > @@ -847,7 +847,7 @@ _initialize_guile (void) > #if HAVE_GUILE > { > #ifdef HAVE_SIGPROCMASK > - sigset_t sigchld_mask, prev_mask; > + sigset_t guile_init_mask, prev_mask; > #endif > > /* The Python support puts the C side in module "_gdb", leaving the Python > @@ -867,9 +867,23 @@ _initialize_guile (void) > have SIGCHLD blocked. PR 17247. > Really libgc and Guile should do this, but we need to work with > libgc 7.4.x. */ > - sigemptyset (&sigchld_mask); > - sigaddset (&sigchld_mask, SIGCHLD); > - sigprocmask (SIG_BLOCK, &sigchld_mask, &prev_mask); > + sigemptyset (&guile_init_mask); > + sigaddset (&guile_init_mask, SIGCHLD); > + /* Also block other asynchronous signals used by GDB. See event-top.c. > + Really we want to block every signal here except for those specifically > + used by Guile (e.g., GC threads), but this is safer for now. */ > + sigaddset (&guile_init_mask, SIGINT); > + sigaddset (&guile_init_mask, SIGTERM); > +#ifdef SIGQUIT > + sigaddset (&guile_init_mask, SIGQUIT); > +#endif > +#ifdef SIGHUP > + sigaddset (&guile_init_mask, SIGHUP); > +#endif > +#ifdef SIGWINCH > + sigaddset (&guile_init_mask, SIGWINCH); > +#endif > + sigprocmask (SIG_BLOCK, &guile_init_mask, &prev_mask); > #endif What about platforms that don't have sigprocmask, but do have SIGINT? Don't we want to block SIGINT on those platforms?
On Sat, Aug 29, 2015 at 12:11 PM, Eli Zaretskii <eliz@gnu.org> wrote: >> From: Doug Evans <xdje42@gmail.com> >> cc: guile-devel@gnu.org >> Date: Sat, 29 Aug 2015 10:22:11 -0700 >> >> --- a/gdb/guile/guile.c >> +++ b/gdb/guile/guile.c >> @@ -847,7 +847,7 @@ _initialize_guile (void) >> #if HAVE_GUILE >> { >> #ifdef HAVE_SIGPROCMASK >> - sigset_t sigchld_mask, prev_mask; >> + sigset_t guile_init_mask, prev_mask; >> #endif >> >> /* The Python support puts the C side in module "_gdb", leaving the Python >> @@ -867,9 +867,23 @@ _initialize_guile (void) >> have SIGCHLD blocked. PR 17247. >> Really libgc and Guile should do this, but we need to work with >> libgc 7.4.x. */ >> - sigemptyset (&sigchld_mask); >> - sigaddset (&sigchld_mask, SIGCHLD); >> - sigprocmask (SIG_BLOCK, &sigchld_mask, &prev_mask); >> + sigemptyset (&guile_init_mask); >> + sigaddset (&guile_init_mask, SIGCHLD); >> + /* Also block other asynchronous signals used by GDB. See event-top.c. >> + Really we want to block every signal here except for those specifically >> + used by Guile (e.g., GC threads), but this is safer for now. */ >> + sigaddset (&guile_init_mask, SIGINT); >> + sigaddset (&guile_init_mask, SIGTERM); >> +#ifdef SIGQUIT >> + sigaddset (&guile_init_mask, SIGQUIT); >> +#endif >> +#ifdef SIGHUP >> + sigaddset (&guile_init_mask, SIGHUP); >> +#endif >> +#ifdef SIGWINCH >> + sigaddset (&guile_init_mask, SIGWINCH); >> +#endif >> + sigprocmask (SIG_BLOCK, &guile_init_mask, &prev_mask); >> #endif > > What about platforms that don't have sigprocmask, but do have SIGINT? > Don't we want to block SIGINT on those platforms? Do they have threads, and how does one block SIGINT on those platforms?
> Date: Sat, 29 Aug 2015 12:20:24 -0700 > From: Doug Evans <xdje42@gmail.com> > Cc: "gdb-patches@sourceware.org" <gdb-patches@sourceware.org>, guile-devel <guile-devel@gnu.org> > > > What about platforms that don't have sigprocmask, but do have SIGINT? > > Don't we want to block SIGINT on those platforms? > > Do they have threads They might. (The only way I've succeeded to have a working Guile on Windows was to disable threads, but I hope that bug will be fixed one day.) > and how does one block SIGINT on those platforms? With a call to 'signal', I guess.
On Sat, Aug 29, 2015 at 1:16 PM, Eli Zaretskii <eliz@gnu.org> wrote: >> Date: Sat, 29 Aug 2015 12:20:24 -0700 >> From: Doug Evans <xdje42@gmail.com> >> Cc: "gdb-patches@sourceware.org" <gdb-patches@sourceware.org>, guile-devel <guile-devel@gnu.org> >> >> > What about platforms that don't have sigprocmask, but do have SIGINT? >> > Don't we want to block SIGINT on those platforms? >> >> Do they have threads > > They might. (The only way I've succeeded to have a working Guile on > Windows was to disable threads, but I hope that bug will be fixed one > day.) > >> and how does one block SIGINT on those platforms? > > With a call to 'signal', I guess. I'm guessing that won't work here, we'll need something else. The issue is we need the threads that guile starts to have these signals blocked. Then after guile init returns we unblock the signals.
> Date: Sat, 29 Aug 2015 13:39:55 -0700 > From: Doug Evans <xdje42@gmail.com> > > On Sat, Aug 29, 2015 at 1:16 PM, Eli Zaretskii <eliz@gnu.org> wrote: > >> Date: Sat, 29 Aug 2015 12:20:24 -0700 > >> From: Doug Evans <xdje42@gmail.com> > >> Cc: "gdb-patches@sourceware.org" <gdb-patches@sourceware.org>, guile-devel <guile-devel@gnu.org> > >> > >> > What about platforms that don't have sigprocmask, but do have SIGINT? > >> > Don't we want to block SIGINT on those platforms? > >> > >> Do they have threads > > > > They might. (The only way I've succeeded to have a working Guile on > > Windows was to disable threads, but I hope that bug will be fixed one > > day.) > > > >> and how does one block SIGINT on those platforms? > > > > With a call to 'signal', I guess. > > I'm guessing that won't work here, we'll need something else. > The issue is we need the threads that guile starts > to have these signals blocked. Then after guile init > returns we unblock the signals. I suppose blocking these in the threads that guile starts is necessary because that is the only way to guarantee that those signals will be delivered to the main gdb thread on POSIX systems. On Windows you probably need to do something completely different.
> Date: Sat, 29 Aug 2015 13:39:55 -0700 > From: Doug Evans <xdje42@gmail.com> > Cc: "gdb-patches@sourceware.org" <gdb-patches@sourceware.org>, guile-devel <guile-devel@gnu.org> > > On Sat, Aug 29, 2015 at 1:16 PM, Eli Zaretskii <eliz@gnu.org> wrote: > >> Date: Sat, 29 Aug 2015 12:20:24 -0700 > >> From: Doug Evans <xdje42@gmail.com> > >> Cc: "gdb-patches@sourceware.org" <gdb-patches@sourceware.org>, guile-devel <guile-devel@gnu.org> > >> > >> > What about platforms that don't have sigprocmask, but do have SIGINT? > >> > Don't we want to block SIGINT on those platforms? > >> > >> Do they have threads > > > > They might. (The only way I've succeeded to have a working Guile on > > Windows was to disable threads, but I hope that bug will be fixed one > > day.) > > > >> and how does one block SIGINT on those platforms? > > > > With a call to 'signal', I guess. > > I'm guessing that won't work here, we'll need something else. I don't understand why. Can you explain? Maybe I'm missing something. > The issue is we need the threads that guile starts > to have these signals blocked. Then after guile init > returns we unblock the signals. Inhibit SIGINT ech time before calling Guile and restore it after Guile returns. Wouldn't that do what you want?
> Date: Sat, 29 Aug 2015 23:04:02 +0200 (CEST) > From: Mark Kettenis <mark.kettenis@xs4all.nl> > CC: eliz@gnu.org, gdb-patches@sourceware.org, guile-devel@gnu.org > > I suppose blocking these in the threads that guile starts is necessary > because that is the only way to guarantee that those signals will be > delivered to the main gdb thread on POSIX systems. > > On Windows you probably need to do something completely different. I might be missing something, because I don't see why.
On Sat, Aug 29, 2015 at 7:37 PM, Eli Zaretskii <eliz@gnu.org> wrote: >> Date: Sat, 29 Aug 2015 23:04:02 +0200 (CEST) >> From: Mark Kettenis <mark.kettenis@xs4all.nl> >> CC: eliz@gnu.org, gdb-patches@sourceware.org, guile-devel@gnu.org >> >> I suppose blocking these in the threads that guile starts is necessary >> because that is the only way to guarantee that those signals will be >> delivered to the main gdb thread on POSIX systems. >> >> On Windows you probably need to do something completely different. > > I might be missing something, because I don't see why. The goal here is to block these signals from being sent to the threads that Guile (or more specifically libgc) creates. Posix threads inherit the current value of the process's sigmask, so as long as the threads are started during Guile initialization, we can achieve this by blocking the signals before calling Guile's init routine and then restoring them after Guile's init routine returns. Note that we don't want to prevent gdb from getting the signals, we just want them to be sent to gdb's main thread. Not sure how to do that on windows.
> Date: Mon, 31 Aug 2015 22:05:59 -0700 > From: Doug Evans <xdje42@gmail.com> > Cc: Mark Kettenis <mark.kettenis@xs4all.nl>, > "gdb-patches@sourceware.org" <gdb-patches@sourceware.org>, guile-devel <guile-devel@gnu.org> > > On Sat, Aug 29, 2015 at 7:37 PM, Eli Zaretskii <eliz@gnu.org> wrote: > >> Date: Sat, 29 Aug 2015 23:04:02 +0200 (CEST) > >> From: Mark Kettenis <mark.kettenis@xs4all.nl> > >> CC: eliz@gnu.org, gdb-patches@sourceware.org, guile-devel@gnu.org > >> > >> I suppose blocking these in the threads that guile starts is necessary > >> because that is the only way to guarantee that those signals will be > >> delivered to the main gdb thread on POSIX systems. > >> > >> On Windows you probably need to do something completely different. > > > > I might be missing something, because I don't see why. > > The goal here is to block these signals from being sent to the threads > that Guile (or more specifically libgc) creates. Why only libgc? Don't we want to block these signals in any Guile code invoked later by GDB? > Not sure how to do that on windows. That problem doesn't exist on Windows, but what about Guile application threads launched later?
On Tue, Sep 1, 2015 at 7:35 AM, Eli Zaretskii <eliz@gnu.org> wrote: >> The goal here is to block these signals from being sent to the threads >> that Guile (or more specifically libgc) creates. > > Why only libgc? Don't we want to block these signals in any Guile > code invoked later by GDB? Any threads created later are required to DTRT themselves. [Same as on python.]
> Date: Tue, 1 Sep 2015 08:22:44 -0700 > From: Doug Evans <xdje42@gmail.com> > Cc: Mark Kettenis <mark.kettenis@xs4all.nl>, > "gdb-patches@sourceware.org" <gdb-patches@sourceware.org>, guile-devel <guile-devel@gnu.org> > > On Tue, Sep 1, 2015 at 7:35 AM, Eli Zaretskii <eliz@gnu.org> wrote: > >> The goal here is to block these signals from being sent to the threads > >> that Guile (or more specifically libgc) creates. > > > > Why only libgc? Don't we want to block these signals in any Guile > > code invoked later by GDB? > > Any threads created later are required to DTRT themselves. > [Same as on python.] Then I guess this problem can be ignored for Windows.
diff --git a/gdb/guile/guile.c b/gdb/guile/guile.c index 4abf5c5..e9ef70b 100644 --- a/gdb/guile/guile.c +++ b/gdb/guile/guile.c @@ -847,7 +847,7 @@ _initialize_guile (void) #if HAVE_GUILE { #ifdef HAVE_SIGPROCMASK - sigset_t sigchld_mask, prev_mask; + sigset_t guile_init_mask, prev_mask; #endif /* The Python support puts the C side in module "_gdb", leaving the Python @@ -867,9 +867,23 @@ _initialize_guile (void) have SIGCHLD blocked. PR 17247. Really libgc and Guile should do this, but we need to work with libgc 7.4.x. */ - sigemptyset (&sigchld_mask); - sigaddset (&sigchld_mask, SIGCHLD); - sigprocmask (SIG_BLOCK, &sigchld_mask, &prev_mask); + sigemptyset (&guile_init_mask); + sigaddset (&guile_init_mask, SIGCHLD); + /* Also block other asynchronous signals used by GDB. See event-top.c. + Really we want to block every signal here except for those specifically + used by Guile (e.g., GC threads), but this is safer for now. */ + sigaddset (&guile_init_mask, SIGINT); + sigaddset (&guile_init_mask, SIGTERM); +#ifdef SIGQUIT + sigaddset (&guile_init_mask, SIGQUIT); +#endif +#ifdef SIGHUP + sigaddset (&guile_init_mask, SIGHUP); +#endif +#ifdef SIGWINCH + sigaddset (&guile_init_mask, SIGWINCH); +#endif + sigprocmask (SIG_BLOCK, &guile_init_mask, &prev_mask); #endif /* scm_with_guile is the most portable way to initialize Guile.