linux-kernel - Re: [PATCH v2 07/43] blackfin: Use set_current_blocked() and block

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Date:	Sat, 20 Aug 2011 09:36:43 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Mike Frysinger <vapier@...too.org>
Cc:	Oleg Nesterov <oleg@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 07/43] blackfin: Use set_current_blocked() and
 block_sigmask()

On Sat, 2011-08-20 at 00:00 -0400, Mike Frysinger wrote:
> On Fri, Aug 19, 2011 at 12:46, Matt Fleming wrote:
> > --- a/arch/blackfin/kernel/signal.c
> > +++ b/arch/blackfin/kernel/signal.c
> > -       if (ret == 0) {
> > -               spin_lock_irq(&current->sighand->siglock);
> > -               sigorsets(&current->blocked, &current->blocked,
> > -                         &ka->sa.sa_mask);
> > -               if (!(ka->sa.sa_flags & SA_NODEFER))
> > -                       sigaddset(&current->blocked, sig);
> > -               recalc_sigpending();
> > -               spin_unlock_irq(&current->sighand->siglock);
> > -       }
> > +       if (ret == 0)
> > +               block_sigmask(ka, sig);
> 
> the Blackfin version holds siglock and calls recalc_sigpending() while
> block_sigmask() does neither.  i'm guessing that is expected behavior
> now ?

Yah, set_current_blocked() inside of block_sigmask() still grabs siglock
and calls recalc_sigpending() for you. Reading current->blocked inside
of block_sigmask() is fine and the sigorsets() is OK because we're
modifying a stack variable, so only grabbing the lock inside of
set_current_blocked() is safe.

-- 
Matt Fleming, Intel Open Source Technology Center

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