On Sat, 2007-11-03 at 13:01 +0800, Andreas Dilger wrote: > On Nov 02, 2007 17:35 -0700, Mingming Cao wrote: > > Index: linux-2.6.24-rc1/fs/ext4/mballoc.c > > =================================================================== > > --- linux-2.6.24-rc1.orig/fs/ext4/mballoc.c 2007-11-02 17:22:18.000000000 -0700 > > +++ linux-2.6.24-rc1/fs/ext4/mballoc.c 2007-11-02 17:23:02.000000000 -0700 > > @@ -4006,7 +4006,8 @@ static void ext4_mb_group_or_file(struct > > return; > > > > BUG_ON(ac->ac_lg != NULL); > > - ac->ac_lg = &sbi->s_locality_groups[smp_processor_id()]; > > + ac->ac_lg = &sbi->s_locality_groups[get_cpu()]; > > + put_cpu(); > > > > /* we're going to use group allocation */ > > ac->ac_flags |= EXT4_MB_HINT_GROUP_ALLOC; > > Shouldn't the put_cpu() be after ac->ac_lg is no longer being used? > I guess there would otherwise be a danger of other processes using > the same s_locality_groups[] struct? >From the code, the concurrent use of the same s_locality_groups is being protected by the ac_lg->lg_sem. The put_cpu() instruction is before the lock is taken. Mingming - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
