On Thu, Aug 25, 2011 at 08:52:08PM +0200, Jan Kiszka wrote: > On 2011-08-25 20:19, Michael S. Tsirkin wrote: > > On Thu, Aug 25, 2011 at 03:06:01PM +0200, Jan Kiszka wrote: > >>> I took a look at the sysfs triggered pci reset function and don't see any way > >>> that the controlling device driver ever gets to be involved in this reset. > >>> If code outside the ipr driver were to reset the adapter, the adapter firmware > >>> would be left in an uninitialized state and until scsi core starts timing > >>> out ops and driving EH, the card would be unusable. I can't imagine the > >>> ipr driver is unique in this. > >> > >> Right, that's why a PCI core service is needed for coordination. > >> > >> Jan > > > > But why do we want to trigger reset through sysfs while the > > driver runs? > > A perfectly valid race conditions are created by KVM and VFIO: shared > IRQ handler is triggered while the user space part wants to reset the > assigned device. OK, that would be solved by blocking sysfs reset while config access is blocked, right? > I'm quite sure that this how I first caused this bug to > show up (it triggered for an assigned device with a shared busy IRQ line > during QEMU startup, ie. the initial guest reset). > > Jan > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
