Re: [RFC PATCH V2 FIX] Fix deadlock during find

Michael Trimarchi
2008-11-26T13:04:28Z

Hi,

----- Messaggio originale -----
> Da: Paul Mundt <lethal@linux-sh.org>
> A: Michael Trimarchi <trimarchimichael@yahoo.it>
> Cc: linux-sh@vger.kernel.org
> Inviato: Martedì 25 novembre 2008, 18:06:03
> Oggetto: Re: [RFC PATCH V2 FIX] Fix deadlock during find
>
> On Thu, Nov 20, 2008 at 02:45:02PM +0100, Michael Trimarchi wrote:
> > Fix a deadlock during find.
> >
> > Continue with testing i find and errata implementation in the unlock.
> > This patch fix the deadlock.
> >
> > Signed-off-by: Michael Trimarchi
> >
> > ---
> > arch/sh/include/asm/mutex_sh.h | 12 ++++++------
> > 1 files changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/sh/include/asm/mutex_sh.h b/arch/sh/include/asm/mutex_sh.h
> > index c98e875..c65f19e 100644
> > --- a/arch/sh/include/asm/mutex_sh.h
> > +++ b/arch/sh/include/asm/mutex_sh.h
> > @@ -48,18 +48,18 @@ __mutex_fastpath_lock_retval(atomic_t *count, int
> (*fail_fn)(atomic_t *))
> > static inline void
> > __mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
> > {
> > - int __res, __orig;
> > + int __res;
> >
> > __asm__ __volatile__ (
> > - "movli.l @%2, %0 \n\t"
> > - "mov %0, %1 \n\t"
> > + "1: movli.l @%1, %0 \n\t"
> > "add #1, %0 \n\t"
> > - "movco.l %0, @%2 "
> > - : "=&z" (__res), "=&r" (__orig)
> > + "movco.l %0, @%1 \n\t"
> > + "bf 1b\n\t"
> > + : "=&z" (__res)
> > : "r" (&(count)->counter)
> > : "t" );
> >
> > - if (unlikely(__orig != 0))
> > + if (unlikely(__res <= 0))
> > fail_fn(count);
> > }
> >
>
> Making __mutex_fastpath_unlock() loop seems counter-intuitive. I think
> the initial test on __orig is what was causing you issues rather than the
> need for looping. I do see why ARM did it this way, but we don't have
> precisely the same semantics there.
>
> Does the following patch against current git pass your test cases?
>
This is an old one patch. You integrate the correct one V3

Regards MIchael