Messages in this thread | | | Date | Mon, 4 Nov 2013 12:55:24 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH 1/2] srcu: API for barrier after srcu read unlock |
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On Mon, Nov 04, 2013 at 10:36:17PM +0200, Michael S. Tsirkin wrote: > srcu read lock/unlock include a full memory barrier > but that's an implementation detail. > Add an API for make memory fencing explicit for > users that need this barrier, to make sure we > can change it as needed without breaking all users. > > Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> --- > include/linux/srcu.h | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/include/linux/srcu.h b/include/linux/srcu.h > index c114614..9b058ee 100644 > --- a/include/linux/srcu.h > +++ b/include/linux/srcu.h > @@ -237,4 +237,18 @@ static inline void srcu_read_unlock(struct srcu_struct *sp, int idx) > __srcu_read_unlock(sp, idx); > } > > +/** > + * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock > + * > + * Converts the preceding srcu_read_unlock into a two-way memory barrier. > + * > + * Call this after srcu_read_unlock, to guarantee that all memory operations > + * that occur after smp_mb__after_srcu_read_unlock will appear to happen after > + * the preceding srcu_read_unlock. > + */ > +static inline void smp_mb__after_srcu_read_unlock(void) > +{ > + /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */ > +} > + > #endif > -- > MST >
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