On Thu, 2008-04-03 at 15:07 -0700, Andrew Vasquez wrote: > On Thu, 03 Apr 2008, James Bottomley wrote: > > > On Thu, 2008-04-03 at 13:13 -0700, Andrew Vasquez wrote: > > > There's no need to use the heavier (albiet safer) > > > *_irq[save|restore]() locking primitives within the driver's > > > interrupt handlers, interrupts are guaranteed to be > > > non-reentrant. Use lightweight spin_lock() and spin_unlock() > > > primitives while acquiring the hardware_lock. > > > > The above statement isn't entirely true: interrupts are not guaranteed > > to be non re-entrant. They are guaranteed not to be re-entered from the > > *same* interrupt, but if you've got more than one card, the interrupt > > routine can be executing simultaneously on an SMP system which is in > > contravention of the classical definition of re-entrancy. > > > > So, the rules for locks in interrupt is that as long as the lock is > > unique per interrupting instance (which it looks like yours are) > > They are... Thanks. > > you can > > get away with not requiring interrupt disables within critical sections > > but if you have a more global lock which could be taken by different > > interrupting entities then you must do interrupt disables still. > > Thanks for the clarification. Would you like me to resubmit with an > altered changelog or can the current one glide in? No .. that's OK ... I can't think of a better way to word it that won't take up whole sentences. James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
