On 05/27/14 07:40, Hannes Reinecke wrote: > On 05/26/2014 05:14 PM, Bart Van Assche wrote: >> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c >> index f17aa7a..5232583 100644 >> --- a/drivers/scsi/scsi_error.c >> +++ b/drivers/scsi/scsi_error.c >> @@ -193,7 +193,7 @@ scsi_abort_command(struct scsi_cmnd *scmd) >> SCSI_LOG_ERROR_RECOVERY(3, >> scmd_printk(KERN_INFO, scmd, >> "scmd %p previous abort failed\n", scmd)); >> - cancel_delayed_work(&scmd->abort_work); >> + WARN_ON_ONCE(delayed_work_pending(&scmd->abort_work)); >> return FAILED; >> } >> >> > The first bit is okay, the second isn't. > > The second bit is for these cases where the abort got scheduled (in > scsi_abort_command()), but the workqueue didn't get executed by the time > the next timeout occured. > I know, highly unlikely, but there is no safeguarding that it _cannot_ > happen. > So the second cancel_delayed_work() has to stay. But how could that next timeout occur while abort_work is still pending ? The block layer removes a request from the timeout list before invoking the timeout handler (see also blk_rq_check_expired()). This means that no block layer timers are active after abort_work has been scheduled and before scmd_eh_abort_handler() is called. This also means that a second timeout can only occur after a SCSI command has been reinserted to a SCSI device queue. And such a reinsertion can only occur after scmd_eh_abort_handler() has started. The pending bit is cleared from a work struct before the associated handler is invoked. This is why I think the above cancel_delayed_work() statement is not necessary. Or did I perhaps overlook something ? Bart. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
