Messages in this thread |  | | | Date | Fri, 24 Feb 2012 12:01:19 -0500 | | From | Jeff Garzik <> | | Subject | Re: linux-next: pata_acpi.ko crashes at ata_ap_acpi_handle() |
| |
On 02/24/2012 09:26 AM, Alan Cox wrote: >> We can see the code in ata_ap_acpi_handle()accesses ap->scsi_host filed without checking if it’s initialized, which causes NULL pointer panic. Meanwhile, ata_pci_sff_activate_host() calls ata_host_register(), which calls ata_scsi_add_hosts() to initialize scsi_host field. Both calls are after ata_host_start() in a must-visit code path. I believe ata_scsi_add_hosts() is the first place for initialization because it does not check if scsi_host field is NULL either. So it makes no sense to access ap->scsi_host in ata_ap_acpi_handle(). > > This appears to be caused by broken changes to the libata code from > Matthew Garrett and others who introduced a dependancy on scsi_host which > isn't safe to do because drivers can touch the ACPI earlier than the > scsi registration and in fact *NEED* to do so. > > Jeff - can we get these patches dropped back out for the moment - they > cause a regression and boot crash in pata_acpi. > > The stack from 75d22cd567cac6fe2af8acb33f6ebcd16876d250 needs to get > punted and the scsi_host indirection removed and fixed up for it to work > safely with existing libata drivers. > > I don't see an obvious way to fix up the existing ordering dependancies, > especially on the pata_acpi side but if someone has bright ideas there > that would probably be the best choice. Right now these patches stop any > ACPI querying being done during the port setup. We need to do those > queries in order to know if the port can be driven by ACPI and what modes > we can make work.
Sigh. You are right. I kept waiting and waiting for fix-up patches, but they just need more baking and thinking it seems.
Jeff
-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |