On Wed, Sep 26, 2007 at 01:19:05PM -0400, Dmitry Torokhov wrote: > On 9/26/07, Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote: > > On Wed, Sep 26, 2007 at 09:16:55AM -0400, Dmitry Torokhov wrote: > > > > > No, I don't think synchronize_irq() will work for me. While in i8042 I > > > know there are 2 possible IRQs (so I'd need 2 calls to > > > synchronize_irq()) other drivers may not know what IRQ triggered their > > > handler (or whether it was an IRQ at all). > > > > > > Actually, I need clarifucation on what you mean by "interrupt > > > handlers" in sync_all_irqs(). Right now (if I understand it correctly) > > > synchronize_sched() in mainline will wait for completion of all > > > IRQ-like contexts. By IRQ-like context I mean code guardede by > > > spinlock + IRQ off. Serio (input) drivers have their "interrupt" > > > routines run in that IRQ-like context. They may be invoked as a result > > > of real IRQ being raised but they also be invoked as a result of > > > userspace action of some sort. It all depends on implementation of > > > underlying serio port. So if sync_all_irqs() only waits for real IRQ > > > handlers to complete it is not sufficient in my case... > > > > The synchronize_all_irqs() will not return until: > > > > 1. All pre-existing hardirqs have completed. > > > > 2. All pre-existing threaded irqs have completed. > > > > 3. All preempt_disable() regions of code have completed. > > > > 4. All irq-disable regions of code have completed. > > > > It will not necessarily wait for all softirqs to complete, but > > then again, synchronize_sched() in non-rt might not wait for all > > softirqs either, for example, if ksoftirqd is handling softirqs. > > > > Does that do what you need, or am I missing a case that needs > > to be covered? > > As long as the list includes code guarded by > spin_lock_irqsave()/spin_unlock_irqrestore() I am happy. Does this > count as an irq-disable region? Peter said earlier that in -rt such > code still runs with IRQs enabled... If I remember correctly, it depends on whether the underlying spinlock is spinlock_t or raw_spinlock_t. However, doesn't spin_lock_irqsave() disable preemption in both cases (either explicitly for the spinlock_t case or implicitly via irq disable in the raw_spinlock_t case)? If so, synchronize_all_irqs() should do what you want in both cases. Thanx, Paul - To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
