Messages in this thread | | | Subject | Re: [PATCH 03/20] x86/ticketlock: Use C for __ticket_spin_unlock | From | Eric Dumazet <> | Date | Wed, 03 Nov 2010 16:13:38 +0100 |
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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 >
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