29.08.2013, 19:25, "Waiman Long" <waiman.l...@hp.com>: > What I have been thinking is to set a flag in an architecture specific > header file to tell if the architecture need a memory barrier. The > generic code will then either do a smp_mb() or barrier() depending on > the presence or absence of the flag. I would prefer to do more in the > generic code, if possible.
If you use flag then you'll have to check it manually. It is better to add new smp_mb variant, I suggest calling it smp_mb_before_store(), and define it to barrier() on x86. But the same constraints as to UNLOCK_LOCK_PREFIX should apply here, so it will be something like this: arch/x86/include/asm/barrier.h: +#if defined(CONFIG_X86_32) && \ + (defined(CONFIG_X86_OOSTORE) || defined+(CONFIG_X86_PPRO_FENCE)) +/* + * On PPro SMP or if we are using OOSTORE, we use a full memory barrier + * (PPro errata 66, 92) + */ +# define smp_mb_before_store() smp_mb() +#else +# define smp_mb_before_store() barrier() +#endif -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
