linux-kernel - Re: [PATCH 1/3] signals: sigqueue_free: don't free sigqueue if it is queued

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Date:	Thu, 22 May 2008 14:50:57 -0700 (PDT)
From:	Roland McGrath <roland@...hat.com>
To:	Oleg Nesterov <oleg@...sign.ru>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Austin Clements <amdragon+kernelbugzilla@....edu>,
	Ingo Molnar <mingo@...e.hu>, john stultz <johnstul@...ibm.com>,
	Michael Kerrisk <mtk.manpages@...glemail.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] signals: sigqueue_free: don't free sigqueue if it is queued

> 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
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