From 5f38433885245dce82aa53c20a6b2efbe81ae350 Mon Sep 17 00:00:00 2001 From: Michael Holzheu Date: Fri, 24 Mar 2006 03:15:28 -0800 Subject: [PATCH] s390: fix endless retry loop in tape driver If a tape device is assigned to another host, the interrupt for the assign operation comes back with deferred condition code 1. Under some conditions this can lead to an endless loop of retries. Check if the current request is still in IO in deferred condition code handling and prevent retries when the request has already been cancelled. Signed-off-by: Michael Holzheu Signed-off-by: Martin Schwidefsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/s390/char/tape_core.c | 32 +++++++++++++++++++++++++++----- 1 file changed, 27 insertions(+), 5 deletions(-) (limited to 'drivers/s390/char/tape_core.c') diff --git a/drivers/s390/char/tape_core.c b/drivers/s390/char/tape_core.c index 5d17149a652..c6fab5dbdd4 100644 --- a/drivers/s390/char/tape_core.c +++ b/drivers/s390/char/tape_core.c @@ -761,6 +761,13 @@ __tape_start_next_request(struct tape_device *device) */ if (request->status == TAPE_REQUEST_IN_IO) return; + /* + * Request has already been stopped. We have to wait until + * the request is removed from the queue in the interrupt + * handling. + */ + if (request->status == TAPE_REQUEST_DONE) + return; /* * We wanted to cancel the request but the common I/O layer @@ -1023,6 +1030,20 @@ tape_do_io_interruptible(struct tape_device *device, return rc; } +/* + * Stop running ccw. + */ +int +tape_cancel_io(struct tape_device *device, struct tape_request *request) +{ + int rc; + + spin_lock_irq(get_ccwdev_lock(device->cdev)); + rc = __tape_cancel_io(device, request); + spin_unlock_irq(get_ccwdev_lock(device->cdev)); + return rc; +} + /* * Tape interrupt routine, called from the ccw_device layer */ @@ -1068,12 +1089,12 @@ __tape_do_irq (struct ccw_device *cdev, unsigned long intparm, struct irb *irb) * error might still apply. So we just schedule the request to be * started later. */ - if (irb->scsw.cc != 0 && (irb->scsw.fctl & SCSW_FCTL_START_FUNC)) { - PRINT_WARN("(%s): deferred cc=%i. restaring\n", - cdev->dev.bus_id, - irb->scsw.cc); + if (irb->scsw.cc != 0 && (irb->scsw.fctl & SCSW_FCTL_START_FUNC) && + (request->status == TAPE_REQUEST_IN_IO)) { + DBF_EVENT(3,"(%08x): deferred cc=%i, fctl=%i. restarting\n", + device->cdev_id, irb->scsw.cc, irb->scsw.fctl); request->status = TAPE_REQUEST_QUEUED; - schedule_work(&device->tape_dnr); + schedule_delayed_work(&device->tape_dnr, HZ); return; } @@ -1287,4 +1308,5 @@ EXPORT_SYMBOL(tape_dump_sense_dbf); EXPORT_SYMBOL(tape_do_io); EXPORT_SYMBOL(tape_do_io_async); EXPORT_SYMBOL(tape_do_io_interruptible); +EXPORT_SYMBOL(tape_cancel_io); EXPORT_SYMBOL(tape_mtop); -- cgit v1.2.3