linux-kernel - Re: Bash not reacting to Ctrl-C

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Message-ID: <20110211144155.GD3920@ucw.cz>
Date:	Fri, 11 Feb 2011 15:41:55 +0100
From:	Pavel Machek <pavel@....cz>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Tejun Heo <tj@...nel.org>,
	roland@...hat.com, jan.kratochvil@...hat.com,
	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>,
	Fr?d?ric Weisbecker <fweisbec@...il.com>
Subject: Re: Bash not reacting to Ctrl-C

Hi!

> > set_job_status_and_cleanup() notice wait_sigint_received and send
> > SIGINT to itself (termsig_handler (SIGINT)), but somehow it assumes
> > that the last foreground job should be terminated by SIGINT too:
> >
> > 	 else if (wait_sigint_received && (WTERMSIG (child->status) == SIGINT) &&
> >
> > Then the next wait_for() clears wait_sigint_received and bash
> > looses ^C
> 
> IOW.
> 
> Now that it is clear what happens, the test-case becomes even more
> trivial:
> 
> 	bash-4.1$ ./bash -c 'while true; do /bin/true; done'
> 	^C^C
> 
> needs 4-5 attempts on my machine.

Huh, this happened so often to me that I assumed it is a feature
:-(. Reproducible on both up arm and 4way x86...

Ok, it would be very good to get it fixed.


									Pavel

> --- bash-4.1/jobs.c~ctrlc_exit_race	2011-02-07 13:52:48.000000000 +0100
> +++ bash-4.1/jobs.c	2011-02-07 13:55:30.000000000 +0100
> @@ -3299,7 +3299,7 @@ set_job_status_and_cleanup (job)
>  	 signals are sent to process groups) or via kill(2) to the foreground
>  	 process by another process (or itself).  If the shell did receive the
>  	 SIGINT, it needs to perform normal SIGINT processing. */
> -      else if (wait_sigint_received && (WTERMSIG (child->status) == SIGINT) &&
> +      else if (wait_sigint_received /*&& (WTERMSIG (child->status) == SIGINT)*/ &&
>  	      IS_FOREGROUND (job) && IS_JOBCONTROL (job) == 0)
>  	{
>  	  int old_frozen;


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