On Fri, Jul 17, 2015 at 11:14:14PM +0100, Benjamin Herrenschmidt wrote:
> On Fri, 2015-07-17 at 10:32 +0100, Will Deacon wrote:
> > static inline void arch_spin_unlock(arch_spinlock_t *lock)
> > {
> > - SYNC_IO;
> > - __asm__ __volatile__("# arch_spin_unlock\n\t"
> > - PPC_RELEASE_BARRIER: : :"memory");
> > + smp_mb();
> > lock->slock = 0;
> > }
>
> That probably needs to be mb() in case somebody has the expectation that
> it does a barrier vs. DMA on UP.
Hmm, but on !SMP doesn't arch_spin_unlock effectively expand to barrier()
in the core code?
Will
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