Hi Tejun, due to your commit 31cc23b34913bc173680bdc87af79e551bf8cc0d libata now sets max_host_blocked and max_device_blocked to 1 for all devices it manages. Under certain conditions this may lead to system lockups due to infinite recursion as I have explained to James on the scsi list (kept you cc-ed). James told me that it was the business of libata to make sure that such a recursion cannot happen. In my discussion with James I imprudently claimed that this was easy to fix in libata. However, after giving the matter some thought, I'm not at all sure as to what exactly should be done about it. The easy bit is that max_host_blocked and max_device_blocked should be left alone as long as the low level driver does not provide the ->qc_defer() callback. But even if the driver has defined this callback, ata_std_qc_defer() for one will not prevent this recursion on a uniprocessor, whereas things might work out well on an SMP system due to the lock fiddling in the scsi midlayer. As a conclusion, the current implementation makes it imperative to leave max_host_blocked and max_device_blocked alone on a uniprocessor system. For SMP systems the current implementation might just be fine but even there it might just as well be a good idea to make the adjustment depending on ->qc_defer != NULL. Any ideas? Regards, Elias - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
