Messages in this thread | | | Date | Mon, 8 Aug 2011 09:24:31 +0300 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH] uio/gen-pci: don't enable interrupts in ISR |
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On Fri, Aug 05, 2011 at 02:15:07AM +0200, Hans J. Koch wrote: > On Fri, Aug 05, 2011 at 12:04:13AM +0300, Michael S. Tsirkin wrote: > > On Thu, Aug 04, 2011 at 10:46:06PM +0200, Sebastian Andrzej Siewior wrote: > > > As reported by Anthony in a short way: > > > > > > |irq 17 handler uio_interrupt+0x0/0x68 enabled interrupts > > > |NIP [c0069d84] handle_irq_event_percpu+0x260/0x26c > > > > > > The problem here is that spin_unlock_irq() enables the interrupts which > > > is a no-no in interrupt context because they always run with interrupts > > > disabled. This is the case even if IRQF_DISABLED has not been specified > > > since v2.6.35. Therefore this patch uses simple spin_locks(). > > > > > > Looking at it further here is only one spot where the lock is hold. So > > > giving the fact that an ISR is not reentrant and is not executed on two > > > cpus at the same time why do we need a lock here? > > > > I'm not sure anymore. I think the idea was to use > > it for synchronization down the road somehow, > > but it never materialized. Let's drop that lock completely. > > That sounds reasonable. > > > > > > The driver lacks of ->irqcontrol function so I guess the interrupt is > > > enabled via direct PCI-access in userland. > > > > Through sysfs. > > How? With /sys/devices/pci.../enable ? > > Thanks, > Hans
No. By writing to the command register using /sys/bus/pci/devices/.../config
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