On Fri, 2 Nov 2012, Paul E. McKenney wrote: > On Sat, Nov 03, 2012 at 12:01:47AM +0800, Shan Wei wrote: > > From: Shan Wei <davids...@tencent.com> > > > > Signed-off-by: Shan Wei <davids...@tencent.com> > > --- > > kernel/rcutree.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/kernel/rcutree.c b/kernel/rcutree.c > > index 74df86b..441b945 100644 > > --- a/kernel/rcutree.c > > +++ b/kernel/rcutree.c > > @@ -1960,7 +1960,7 @@ static void force_quiescent_state(struct rcu_state > > *rsp) > > struct rcu_node *rnp_old = NULL; > > > > /* Funnel through hierarchy to reduce memory contention. */ > > - rnp = per_cpu_ptr(rsp->rda, raw_smp_processor_id())->mynode; > > + rnp = __this_cpu_read(rsp->rda->mynode); > > OK, I'll bite... Why this instead of: > > rnp = __this_cpu_read(rsp->rda)->mynode;
Because this_cpu_read fetches a data word from an address. The addres is relocated using a segment prefix (which contains the offset of the current per cpu area). And the address needed here is the address of the field of mynode within a structure that has a per cpu address. -- 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/
