On Wed, 19 Sep 2007 11:16:21 -0400 "Dmitry Torokhov" <[EMAIL PROTECTED]> wrote:
> On 9/19/07, Peter Zijlstra <[EMAIL PROTECTED]> wrote: > > On Wed, 19 Sep 2007 10:17:25 -0400 "Dmitry Torokhov" > > <[EMAIL PROTECTED]> wrote: > > > > > Hi Peter, > > > > > > On 9/19/07, Peter Zijlstra <[EMAIL PROTECTED]> wrote: > > > > Warn when rcu_dereference() is not used in combination with > > > > rcu_read_lock() > > > > > > > > > > According to Paul it is fine to use RCU primitives (when accompanied > > > with proper comments) when the read-size critical section is guarded > > > by spin_lock_irqsave()/spin_lock_irqsrestore() instead of > > > rcu_read_lock()/rcu_read_unlock() and writers synchronize with > > > synchronize_sched(), not synchronize_rcu(). Your patch will trigger > > > warnign on such valid usages. > > > > > > > Sounds fragile to begin with. But you're right in that that is valid > > for Linux as you know it. However in -rt most/all spinlocks are > > converted to sleeping locks. In that case sync_sched() is not enough. > > > > OK, then it goes beyond RCU... We need to come up with something that > can be used to synchronize with IRQ handlers (quite often in driver > code one needs to be sure that current invocation of IRQ handler > completed before doing something). And once we have it splinlock + RCU > users can just use that method. Sound like you want a completion or workqueue. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
