Messages in this thread | | | Date | Fri, 1 Aug 2008 14:10:25 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [patch 01/17] RCU read sched |
| |
On Tue, Jul 15, 2008 at 06:26:05PM -0400, Mathieu Desnoyers wrote: > Add rcu_read_lock_sched() and rcu_read_unlock_sched() to rcupdate.h to match the > recently added write-side call_rcu_sched() and rcu_barrier_sched(). They also > match the no-so-recently-added synchronize_sched(). > > It will help following matching use of the update/read lock primitives. Those > new read lock will replace preempt_disable()/enable() used in pair with > RCU-classic synchronization.
Looks good, but...
synchronize_sched(), call_rcu_sched(), and rcu_barrier_sched() can also pair up with:
o local_irq_save() and local_irq_restore() o local_irq_disable() and local_irq_enable() o spin_lock_irqsave() and spin_lock_irqrestore() o etc. etc.
I do very much like the idea of marking the intent of matching with RCU, but am getting a bit queasy about adding rcu_read_lock_sched_irq() and so on.
Thoughts? Other than having an rcu_read_lock_sched_nop() or some other window-dressing macro that doesn't really do anything? (Which might really be the right thing to do...)
Thanx, Paul
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> > CC: Peter Zijlstra <peterz@infradead.org> > CC: Paul E McKenney <paulmck@linux.vnet.ibm.com> > CC: akpm@linux-foundation.org > --- > include/linux/rcupdate.h | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > Index: linux-2.6-lttng/include/linux/rcupdate.h > =================================================================== > --- linux-2.6-lttng.orig/include/linux/rcupdate.h 2008-07-15 15:28:08.000000000 -0400 > +++ linux-2.6-lttng/include/linux/rcupdate.h 2008-07-15 17:38:02.000000000 -0400 > @@ -133,6 +133,24 @@ struct rcu_head { > #define rcu_read_unlock_bh() __rcu_read_unlock_bh() > > /** > + * rcu_read_lock_sched - mark the beginning of a RCU-classic critical section > + * > + * Should be used with either > + * - synchronize_sched() > + * or > + * - call_rcu_sched() and rcu_barrier_sched() > + * on the write-side to insure proper synchronization. > + */ > +#define rcu_read_lock_sched() preempt_disable() > + > +/* > + * rcu_read_unlock_sched - marks the end of a RCU-classic critical section > + * > + * See rcu_read_lock_sched for more information. > + */ > +#define rcu_read_unlock_sched() preempt_enable() > + > +/** > * rcu_dereference - fetch an RCU-protected pointer in an > * RCU read-side critical section. This pointer may later > * be safely dereferenced. > > -- > Mathieu Desnoyers > Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
| |