On Tue, Nov 04, 2008 at 09:23:03PM +0100, Arnd Bergmann wrote: Big snip.
> > > > I tried to make the locking do only what was needed. I just couldn't get > > it correct unless I used spin_lock_irqsave(). I was able to get the > > system to deadlock otherwise. This is why I posted the driver for > > review, I could use some help here. > > > > It isn't critical anyway. You can always use spin_lock_irqsave(), it is > > just a little slower, but it will always work :) > > I like the documenting character of the spinlock functions. E.g. if you > use spin_lock_irq() in a function, it is obvious that interrupts are enabled, > and if you use spin_lock() on a lock that requires disabling interrupts, > you know that interrupts are already off. > Ok, I've started addressing your comments. I'm having trouble with the locking again. Let me see if my understanding is correct: spin_lock_irqsave() disables interrupts and saves the interrupt state spin_unlock_irqrestore() MAY re-enable interrupts based on the saved flags spin_lock_irq() disables interrupts, and always turns them back on when spin_unlock_irq() is called spin_lock_bh() disables softirqs, spin_unlock_bh() re-enables them spin_lock() and spin_unlock() are just regular spinlocks So, since interrupts are disabled while my interrupt handler is running, I think I should be able to use spin_lock() and spin_unlock(), correct? But sparse gives me the following warning: wqt.c:185:9: warning: context imbalance in 'wqt_interrupt': wrong count at exit wqt.c:185:9: context 'lock': wanted 0, got 1 If I'm using spin_lock_irqsave() and spin_lock_irqrestore() I do not get the same warnings. Therefore I must have some misunderstanding :) Thanks, Ira _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
