On 2018/7/7 2:23, Mike Christie wrote:
On 07/05/2018 09:57 PM, xiu...@redhat.com wrote:
static irqreturn_t uio_interrupt(int irq, void *dev_id)
{
struct uio_device *idev = (struct uio_device *)dev_id;
- irqreturn_t ret = idev->info->handler(irq, idev->info);
+ irqreturn_t ret;
+
+ mutex_lock(&idev->info_lock);
+ if (!idev->info) {
+ ret = IRQ_NONE;
+ goto out;
+ }
+ ret = idev->info->handler(irq, idev->info);
if (ret == IRQ_HANDLED)
uio_event_notify(idev->info);
+out:
+ mutex_unlock(&idev->info_lock);
return ret;
}
Do you need the interrupt related changes in this patch and the first
one?
Actually, the NULL checking is not a must, we can remove this. But the
lock/unlock is needed.
When we do uio_unregister_device -> free_irq does free_irq return
when there are no longer running interrupt handlers that we requested?
If that is not the case then I think we can hit a similar bug. We do:
__uio_register_device -> device_register -> device's refcount goes to
zero so we do -> uio_device_release -> kfree(idev)
and if it is possible the interrupt handler could still run after
free_irq then we would end up doing:
uio_interrupt -> mutex_lock(&idev->info_lock) -> idev access freed memory.
I think this shouldn't happen. Because the free_irq function does not
return until any executing interrupts for this IRQ have completed.
Thanks,
BRs
