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.h | 1 + drivers/s390/char/tape_core.c | 32 +++++++++++++++++++++++++++----- drivers/s390/char/tape_std.c | 15 +++++++-------- 3 files changed, 35 insertions(+), 13 deletions(-) (limited to 'drivers/s390/char') diff --git a/drivers/s390/char/tape.h b/drivers/s390/char/tape.h index 01d865d9379..cd51ace8b61 100644 --- a/drivers/s390/char/tape.h +++ b/drivers/s390/char/tape.h @@ -250,6 +250,7 @@ extern void tape_free_request(struct tape_request *); extern int tape_do_io(struct tape_device *, struct tape_request *); extern int tape_do_io_async(struct tape_device *, struct tape_request *); extern int tape_do_io_interruptible(struct tape_device *, struct tape_request *); +extern int tape_cancel_io(struct tape_device *, struct tape_request *); void tape_hotplug_event(struct tape_device *, int major, int action); static inline int 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); diff --git a/drivers/s390/char/tape_std.c b/drivers/s390/char/tape_std.c index 2f9fe30989a..99cf881f41d 100644 --- a/drivers/s390/char/tape_std.c +++ b/drivers/s390/char/tape_std.c @@ -37,20 +37,19 @@ tape_std_assign_timeout(unsigned long data) { struct tape_request * request; struct tape_device * device; + int rc; request = (struct tape_request *) data; if ((device = request->device) == NULL) BUG(); - spin_lock_irq(get_ccwdev_lock(device->cdev)); - if (request->callback != NULL) { - DBF_EVENT(3, "%08x: Assignment timeout. Device busy.\n", + DBF_EVENT(3, "%08x: Assignment timeout. Device busy.\n", device->cdev_id); - PRINT_ERR("%s: Assignment timeout. Device busy.\n", - device->cdev->dev.bus_id); - ccw_device_clear(device->cdev, (long) request); - } - spin_unlock_irq(get_ccwdev_lock(device->cdev)); + rc = tape_cancel_io(device, request); + if(rc) + PRINT_ERR("(%s): Assign timeout: Cancel failed with rc = %i\n", + device->cdev->dev.bus_id, rc); + } int -- cgit v1.2.3-18-g5258