On Thu, Jun 19, 2014 at 11:01:26AM +0800, Lai Jiangshan wrote: > > + /* > > + * Restore per-cpu operation. smp_store_release() is paired with > > + * smp_load_acquire() in __pcpu_ref_alive() and guarantees that the > > s/smp_load_acquire()/smp_read_barrier_depends()/
Will update. > s/smp_store_release()/smp_mb()/ if you accept my next comment. > > > + * zeroing is visible to all percpu accesses which can see the > > + * following PCPU_REF_DEAD clearing. > > + */ > > + for_each_possible_cpu(cpu) > > + *per_cpu_ptr(pcpu_count, cpu) = 0; > > + > > + smp_store_release(&ref->pcpu_count_ptr, > > + ref->pcpu_count_ptr & ~PCPU_REF_DEAD); > > I think it would be better if smp_mb() is used. smp_wmb() would be better here. We don't need the reader side. > it is documented that smp_read_barrier_depends() and smp_mb() are paired. > Not smp_read_barrier_depends() and smp_store_release(). I don't know. I thought about doing that but the RCU accessors are pairing store_release with read_barrier_depends, so I don't think the particular paring is problematic and store_release is better at documenting what's being barriered. Thanks. -- tejun -- 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/
