Re: [RFC][PATCH -mm 1/5] PM: Make freeze_processes SMP-safe

[Pavel Machek <pavel@suse.cz>]

Hi!

> > > @@ -61,10 +60,13 @@ static inline void freeze_process(struct
> > >  	unsigned long flags;
> > >  
> > >  	if (!freezing(p)) {
> > > -		freeze(p);
> > > -		spin_lock_irqsave(&p->sighand->siglock, flags);
> > > -		signal_wake_up(p, 0);
> > > -		spin_unlock_irqrestore(&p->sighand->siglock, flags);
> > > +		rmb();
> > 
> > If frozen is atomic_t, do we need memory barrier?
> 
> I think so.  For example on x86-64 atomic_read() is just a read.

Sorry for one more change, but


/* set thread flags in other task's structures
 * - see asm/thread_info.h for TIF_xxxx flags available
 */
static inline void set_tsk_thread_flag(struct task_struct *tsk, int
flag)
{
        set_ti_thread_flag(task_thread_info(tsk), flag);
}

...could we use set_tsk_thread_flag and friends to avoid enlarging
task struct?
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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