Re: Use of yield() in the kernel

[Pavel Machek]

Hi!

> > > Here is the list of files using yield(), excluding non-i386 arch specific
> > > files:
> >
> > ...
> >
> > > kernel/suspend.c
> >
> > This is okay.
> 
> Hi Pavel, I agree.  I have some questions about the code though:
> when you come across a thread with (p->flags & PF_FROZEN), why
> break out of the loop?  Why not just skip this thread and go on to
> the

There's "continue;" in there, and it should "just skip this thread".
									Pavel

> next one?  Also, does it matter if the code doing the freezing is itself
> frozen?
> 
> Ciao, Duncan.
> 
> PS: Here is the code, for reference:
> 
>         do {
>                 todo = 0;
>                 read_lock(&tasklist_lock);
>                 do_each_thread(g, p) {
>                         unsigned long flags;
>                         INTERESTING(p);
>                         if (p->flags & PF_FROZEN)
>                                 continue;
> 
>                         /* FIXME: smp problem here: we may not access other proc
> ess' flags
>                            without locking */
>                         p->flags |= PF_FREEZE;
>                         spin_lock_irqsave(&p->sig->siglock, flags);
>                         signal_wake_up(p);
>                         spin_unlock_irqrestore(&p->sig->siglock, flags);
>                         todo++;
>                 } while_each_thread(g, p);
>                 read_unlock(&tasklist_lock);
>                 yield();
>                 if (time_after(jiffies, start_time + TIMEOUT)) {
>                         printk( "\n" );
>                         return todo;
>                 }
>         } while(todo);

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