linux-kernel - Re: [RFC PATCH v2 0/7] signal: sigprocmask fixes

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Date:	Mon, 18 Apr 2011 19:32:24 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Tejun Heo <tj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Nikita V. Youshchenko" <nyoushchenko@...sta.com>,
	Matt Fleming <matt@...sole-pimps.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2 0/7] signal: sigprocmask fixes

On 04/18, Linus Torvalds wrote:
>
> On Mon, Apr 18, 2011 at 6:44 AM, Oleg Nesterov <oleg@...hat.com> wrote:
> >
> > Once again: if we need this, then we need a lot more (trivial) changes
> > like 6/7 and 7/7. Basically every change of ->blocked should be converted
> > to use set_current_blocked(). OTOH, perhaps this makes sense by itself.
>
> Hmm. The more I think about this, the less I like it.
>
> What if the pending thread signal was thread-specific to begin with?

These patches should not change the current behaviour in this case.
We never try to re-target the thread-specific signals. Note that
retarget_shared_pending() checks ->signal->shared_pending only.

> For example, if we have a SIGFPE and a SIGKILL that happen at the same
> time, a dying task may have a SIGFPE pending when it dies, and that
> SIGFPE should _not_ be just distributed out to the other threads in
> the thread group.

Yes, and it won't be.

Btw, we do not need to distribute SIGKILL too, we can change
retarget_shared_pending() to remove SIGKILL from shared_pending.
But this only matters when the caller is exit_signals(), and in
this case it should likely notice signal_group_exit() unless
SIGKILL (in unlikely case) it comes in between.

Or I misunderstood?

Oleg.

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