On Wed, 2012-06-06 at 17:27 +0100, Matthew Garrett wrote: > If the qla driver knows that this is safe, then can't this just be done > in the qla driver? > That is one way of doing it. It makes for a safe change but potentially leaves out a number of other cases that could be helped by wider scope change of disabling Bus Master bit on all PCI devices, until we laboriously debug every one of those cases and then add code to disable Bus Master bit. Sounds to me like it is not a clear win in either case. Do we agree that if device shutdown routine cleanly shuts down all I/O, clearing PCI Bus Mster bit should be safe? If yes, then we only have to deal with broken devices. So the approach could be to disable Bus Master bit unless the device ID matches a blacklist which we update as we find broken devices. I really don't like the idea of maintaining blacklists in the kernel for such things but is that a more practical approach? If blacklist does not sound good, maybe we can ask drivers to tell PCI subsystem if they are not ok with clearing Bus Master bit and then PCI subsystem could skip those devices. -- Khalid ==================================================================== Khalid Aziz Unix Systems Lab (970)898-9214 Hewlett-Packard khalid.aziz@xxxxxx Fort Collins, CO -- 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
