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. 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
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