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From: Roland McGrath <roland@redhat.com>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Austin Clements <amdragon+kernelbugzilla@mit.edu>,
       Ingo Molnar <mingo@elte.hu>, john stultz <johnstul@us.ibm.com>,
       Michael Kerrisk <mtk.manpages@googlemail.com>,
       Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] signals: sigqueue_free: don't free sigqueue if it is queued
In-Reply-To: Oleg Nesterov's message of  Thursday, 22 May 2008 15:12:11 +0400 <20080522111211.GA117@tv-sign.ru>
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Emacs: because you deserve a brk today.
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Date: Thu, 22 May 2008 14:50:57 -0700 (PDT)
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> This is not enough. Again, we remove and free sigqueue but don't discard
> the pending signal. (and we must take into account other rt signals with
> the same si_signo if we want to discard the signal).

Right, of course.  The sigset_t collecting while checking the queue is the
only way to do it.  Note that you need to make it:

	if (q->info.si_code == SI_TIMER && sig >= SIGRTMIN)

because a SI_TIMER could be using a legacy_queue signal number.  In that
case there might have been a second non-timer signal pending with that
number too, which must not get cleared.  Since the only siginfo_t still
recorded is the SI_TIMER one, better to leave it queued than turn it into
an infoless signal, seems to me.


Thanks,
Roland