GNU bug report logs - #20471
Emacs ceased to respond to C-g on a tty; SIGINT became blocked?

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Ivan Shmakov <ivan <at> siamics.net>
To: submit <at> debbugs.gnu.org
Subject: Emacs ceased to respond to C-g on a tty; SIGINT became blocked? 
Date: Thu, 30 Apr 2015 15:30:38 +0000

Package: emacs

	After some unfortunate interaction with a process (or perhaps a
	network connection), one of my Emacs instances (built from Git;
	1c7f0cdc4c1f, 2015-04-27 16:59:11 UTC) ceased to respond to C-g
	on a tty.

	Attaching GDB to it shows no signals being delivered on C-g,
	which (AIUI) hints at either SIGINT being blocked /or/ C-g
	“unbound” from the signal via terminal settings.  I’ve copied
	the latter from a terminal used by a properly working Emacs
	instance with the stty(1) invocation below, yet I still see no
	signals via GDB, which leaves the signal mask as the only point
	of failure that I can think of.

$ stty -F /dev/pts/non-working "$(stty -gF /dev/pts/working)" 

	Any suggestion on how do I debug this issue any further?

	TIA.

-- 
FSF associate member #7257  np. Dance of Death — Iron Maiden … B6A0 230E 334A

Message #8 received at 20471 <at> debbugs.gnu.org (full text, mbox):

From: Andreas Schwab <schwab <at> linux-m68k.org>
To: Ivan Shmakov <ivan <at> siamics.net>
Cc: 20471 <at> debbugs.gnu.org
Subject: Re: bug#20471: Emacs ceased to respond to C-g on a tty;
 SIGINT became blocked?
Date: Thu, 30 Apr 2015 18:00:05 +0200

Ivan Shmakov <ivan <at> siamics.net> writes:

> 	Attaching GDB to it shows no signals being delivered on C-g,
> 	which (AIUI) hints at either SIGINT being blocked /or/ C-g
> 	“unbound” from the signal via terminal settings. I’ve copied
> 	the latter from a terminal used by a properly working Emacs
> 	instance with the stty(1) invocation below, yet I still see no
> 	signals via GDB, which leaves the signal mask as the only point
> 	of failure that I can think of.

A blocked signal would still be visible in the debugger (assuming you
haven't changed the handling of SIGINT in gdb).

Andreas.

-- 
Andreas Schwab, schwab <at> linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Message #11 received at 20471 <at> debbugs.gnu.org (full text, mbox):

From: Ivan Shmakov <ivan <at> siamics.net>
To: 20471 <at> debbugs.gnu.org
Subject: Re: bug#20471: Emacs ceased to respond to C-g on a tty;
 SIGINT became blocked? 
Date: Mon, 04 May 2015 15:55:48 +0000

[Message part 1 (text/plain, inline)]

>>>>> Andreas Schwab <schwab <at> linux-m68k.org> writes:
>>>>> Ivan Shmakov <ivan <at> siamics.net> writes:

 >> Attaching GDB to it shows no signals being delivered on C-g, which
 >> (AIUI) hints at either SIGINT being blocked /or/ C-g “unbound” from
 >> the signal via terminal settings.  I’ve copied the latter from a
 >> terminal used by a properly working Emacs instance with the stty(1)
 >> invocation below, yet I still see no signals via GDB, which leaves
 >> the signal mask as the only point of failure that I can think of.

 >> Any suggestion on how do I debug this issue any further?

 > A blocked signal would still be visible in the debugger

	It’s not what I observe.  Why, SIGINT seem to be ignored by GDB
	itself when it’s attached to that Emacs instance.

 > (assuming you haven't changed the handling of SIGINT in gdb).

	I didn’t.

(gdb) info signals 
Signal        Stop      Print   Pass to program Description

SIGHUP        Yes       Yes     Yes             Hangup
SIGINT        Yes       Yes     No              Interrupt
SIGQUIT       Yes       Yes     Yes             Quit
…

	Just in case, the ps(1) output for two of my Emacs instances
	goes below.  The GDB ‘bt’ output at SIGCONT time (after a
	properly handled C-z) is MIMEd, too.

	To note is that I’ve tried to set a breakpoint on the next line
	of internal_catch (), but it doesn’t seem to ever be triggered.
	Could it hint at some non-local exit issue, perhaps?

$ ps -o pid,pending,blocked,ignored,caught,stat,bsdtime,command \
      -C emacs24 -C emacs25 
  PID   PENDING   BLOCKED   IGNORED    CAUGHT STAT   TIME COMMAND
19987  00000000  00000000  14001000 <cb816eff S+   843:01 emacs24
25806  00000002  04002006  04001000 <db816eff Sl+   52:00 emacs25
$ 

-- 
FSF associate member #7257  http://am-1.org/~ivan/      … 3013 B6A0 230E 334A

[Message part 2 (application/octet-stream, inline)]

Message #14 received at 20471 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Ivan Shmakov <ivan <at> siamics.net>
Cc: 20471 <at> debbugs.gnu.org
Subject: Re: bug#20471: Emacs ceased to respond to C-g on a tty;
 SIGINT became blocked?
Date: Mon, 04 May 2015 19:09:39 +0300

> From: Ivan Shmakov <ivan <at> siamics.net>
> Date: Mon, 04 May 2015 15:55:48 +0000
> 
> >>>>> Andreas Schwab <schwab <at> linux-m68k.org> writes:
> >>>>> Ivan Shmakov <ivan <at> siamics.net> writes:
> 
>  >> Attaching GDB to it shows no signals being delivered on C-g, which
>  >> (AIUI) hints at either SIGINT being blocked /or/ C-g “unbound” from
>  >> the signal via terminal settings.  I’ve copied the latter from a
>  >> terminal used by a properly working Emacs instance with the stty(1)
>  >> invocation below, yet I still see no signals via GDB, which leaves
>  >> the signal mask as the only point of failure that I can think of.
> 
>  >> Any suggestion on how do I debug this issue any further?
> 
>  > A blocked signal would still be visible in the debugger
> 
> 	It’s not what I observe.  Why, SIGINT seem to be ignored by GDB
> 	itself when it’s attached to that Emacs instance.
> 
>  > (assuming you haven't changed the handling of SIGINT in gdb).

Is this on a TTY frame?  If not, then C-g doesn't trigger a SIGINT in
Emacs.

Message #17 received at 20471 <at> debbugs.gnu.org (full text, mbox):

From: Ivan Shmakov <ivan <at> siamics.net>
To: 20471 <at> debbugs.gnu.org
Subject: Re: bug#20471: Emacs ceased to respond to C-g on a tty;
 SIGINT became blocked? 
Date: Mon, 04 May 2015 16:20:26 +0000

>>>>> Eli Zaretskii <eliz <at> gnu.org> writes:
>>>>> From: Ivan Shmakov  Date: Mon, 04 May 2015 15:55:48 +0000
>>>>> Andreas Schwab <schwab <at> linux-m68k.org> writes:

[…]

 >>> A blocked signal would still be visible in the debugger

 >> It’s not what I observe.  Why, SIGINT seem to be ignored by GDB
 >> itself when it’s attached to that Emacs instance.

 >>> (assuming you haven't changed the handling of SIGINT in gdb).

 > Is this on a TTY frame?

	Yes.  FWIW, I use non-tty Emacs frames only occasionally.

 > If not, then C-g doesn't trigger a SIGINT in Emacs.

	Yes.  (I’ve already read that part in keyboard.c.)

PS.  GNU Screen is just so welcoming an environment I can’t give it up
	easily.

-- 
FSF associate member #7257  http://am-1.org/~ivan/      … 3013 B6A0 230E 334A

Message #24 received at 20471 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Ivan Shmakov <ivan <at> siamics.net>
Cc: 20471 <at> debbugs.gnu.org
Subject: Re: bug#20471: Emacs ceased to respond to C-g on a tty; SIGINT
 became blocked? 
Date: Mon, 02 May 2022 11:51:55 +0200

Ivan Shmakov <ivan <at> siamics.net> writes:

> 	After some unfortunate interaction with a process (or perhaps a
> 	network connection), one of my Emacs instances (built from Git;
> 	1c7f0cdc4c1f, 2015-04-27 16:59:11 UTC) ceased to respond to C-g
> 	on a tty.

(I'm going through old bug reports that unfortunately weren't resolved
at the time.)

Are you still seeing this issue in recent Emacs versions?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Message #29 received at 20471 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Ivan Shmakov <ivan <at> siamics.net>
Cc: 20471 <at> debbugs.gnu.org
Subject: Re: bug#20471: Emacs ceased to respond to C-g on a tty; SIGINT
 became blocked? 
Date: Mon, 30 May 2022 20:06:59 +0200

Lars Ingebrigtsen <larsi <at> gnus.org> writes:

> Are you still seeing this issue in recent Emacs versions?

More information was requested, but no response was given within a
month, so I'm closing this bug report.  If the problem still exists,
please respond to this email and we'll reopen the bug report.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Message #34 received at 20471 <at> debbugs.gnu.org (full text, mbox):

From: Ivan Shmakov <ivan <at> siamics.net>
To: 20471 <at> debbugs.gnu.org
Subject: Re: bug#20471: Emacs ceased to respond to C-g on a tty; SIGINT
 became blocked?
Date: Thu, 2 Jun 2022 05:20:47 +0000

>>>>> On 2022-05-02, Lars Ingebrigtsen wrote:
>>>>> IS == Ivan Shmakov wrote:

 > (I’m going through old bug reports that unfortunately weren’t resolved
 > at the time.)

 > Are you still seeing this issue in recent Emacs versions?

	I haven’t put Emacs to much use in a couple of years, so that’d
	be a no.  I cannot readily recall which versions I’ve had this
	bug on, but while very rare (perhaps only happening once in a few
	weeks), I’m pretty certain I’ve encountered it more than once.

 IS> After some unfortunate interaction with a process (or perhaps a
 IS> network connection), one of my Emacs instances (built from Git;
 IS> 1c7f0cdc4c1f, 2015-04-27 16:59:11 UTC) ceased to respond to C-g
 IS> on a tty.

 IS> Attaching GDB to it shows no signals being delivered on C-g,
 IS> which (AIUI) hints at either SIGINT being blocked /or/ C-g
 IS> “unbound” from the signal via terminal settings.

 IS> $ ps -o pid,pending,blocked,ignored,caught,stat,bsdtime,command \
 IS>       -C emacs24 -C emacs25 
 IS>   PID   PENDING   BLOCKED   IGNORED    CAUGHT STAT   TIME COMMAND
 IS> 19987  00000000  00000000  14001000 <cb816eff S+   843:01 emacs24
 IS> 25806  00000002  04002006  04001000 <db816eff Sl+   52:00 emacs25
 IS> $ 

	AIUI, bit 1 set (as in, ‘0 != (mask & 2)’) in the ‘blocked’
	mask above suggests that signal 2 (SIGINT) was indeed blocked.
	Ditto for ‘pending.’

-- 
FSF associate member #7257  np. AUTOEXEC.BAT — Master Boot Record

Message #37 received at 20471 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: 20471 <at> debbugs.gnu.org
Subject: Re: bug#20471: Emacs ceased to respond to C-g on a tty; SIGINT
 became blocked?
Date: Thu, 02 Jun 2022 11:19:19 +0200

Ivan Shmakov <ivan <at> siamics.net> writes:

> 	I haven’t put Emacs to much use in a couple of years, so that’d
> 	be a no.  I cannot readily recall which versions I’ve had this
> 	bug on, but while very rare (perhaps only happening once in a few
> 	weeks), I’m pretty certain I’ve encountered it more than once.

OK; I'm closing this bug report, then.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

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