linux-kernel - Re: [PATCH 2/3] ptrace_untrace: use wake_up_process() instead of bogus signal_wake

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Message-Id: <20090209013804.C99B3FC330@magilla.sf.frob.com>
Date:	Sun,  8 Feb 2009 17:38:04 -0800 (PST)
From:	Roland McGrath <roland@...hat.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Jerome Marchand <jmarchan@...hat.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] ptrace_untrace: use wake_up_process() instead of bogus
	signal_wake_up()

> Both ptrace_stop() and do_signal_stop() pathes always take ->siglock and
> do recalc_sigpending() after wakeup.

Yes, that's true.  But so what?  Why is this a reason to introduce yet
another unconditional (i.e. wrong) wake_up_process?  signal_wake_up does
the job fine, i.e. it calls wake_up_state the right way.  For exactly the
reasons you cited, setting TIF_SIGPENDING is both superfluous and
harmless--its effects will happen upon resume whether it was set or not.
So what's wrong with signal_wake_up?

Thanks,
Roland
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