lkml.org 
[lkml]   [2010]   [Nov]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 03/20] x86/ticketlock: Use C for __ticket_spin_unlock
    From
    Date
    Le mercredi 03 novembre 2010 à 10:59 -0400, Jeremy Fitzhardinge a
    écrit :
    > From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
    >
    > If we don't need to use a locked inc for unlock, then implement it in C.
    >
    > Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
    > ---
    > arch/x86/include/asm/spinlock.h | 33 ++++++++++++++++++---------------
    > 1 files changed, 18 insertions(+), 15 deletions(-)
    >
    > diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
    > index 6711d36..082990a 100644
    > --- a/arch/x86/include/asm/spinlock.h
    > +++ b/arch/x86/include/asm/spinlock.h
    > @@ -33,9 +33,23 @@
    > * On PPro SMP or if we are using OOSTORE, we use a locked operation to unlock
    > * (PPro errata 66, 92)
    > */
    > -# define UNLOCK_LOCK_PREFIX LOCK_PREFIX
    > +static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock)
    > +{
    > + if (sizeof(lock->tickets.head) == sizeof(u8))
    > + asm (LOCK_PREFIX "incb %0"
    > + : "+m" (lock->tickets.head) : : "memory");
    > + else
    > + asm (LOCK_PREFIX "incw %0"
    > + : "+m" (lock->tickets.head) : : "memory");
    > +
    > +}
    > #else
    > -# define UNLOCK_LOCK_PREFIX
    > +static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock)
    > +{
    > + barrier();

    technically speaking, it should be : smp_wmb()

    > + lock->tickets.head++;
    > + barrier();

    Not sure you need this one.

    > +}
    > #endif
    >

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2010-11-03 16:17    [W:0.024 / U:61.244 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site