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Commit 9487cfd3 authored by Stefan Haberland's avatar Stefan Haberland Committed by Martin Schwidefsky
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s390/dasd: fix handling of internal requests 



Internal DASD device driver I/O such as query host access count or
path verification is started using the _sleep_on() function.
To mark a request as started or ended the callback_data is set to either
DASD_SLEEPON_START_TAG or DASD_SLEEPON_END_TAG.

In cases where the request has to be stopped unconditionally the status is
set to DASD_SLEEPON_END_TAG as well which leads to immediate clearing of
the request.
But the request might still be on a device request queue for normal
operation which might lead to a panic because of a BUG() statement in
__dasd_device_process_final_queue() or a list corruption of the device
request queue.

Fix by removing the setting of DASD_SLEEPON_END_TAG in the
dasd_cancel_req() and dasd_generic_requeue_all_requests() functions and
ensure that the request is not deleted in the requeue function.
Trigger the device tasklet in the requeue function and let the normal
processing cleanup the request.

Signed-off-by: default avatarStefan Haberland <sth@linux.vnet.ibm.com>
Reviewed-by: default avatarJan Hoeppner <hoeppner@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 91ab883e

drivers/s390/block/dasd.c

+7 −14
Original line number Original line Diff line number Diff line
@@ -2581,8 +2581,6 @@ int dasd_cancel_req(struct dasd_ccw_req *cqr) 
	case DASD_CQR_QUEUED:

	case DASD_CQR_QUEUED:

		/* request was not started - just set to cleared */

		/* request was not started - just set to cleared */

		cqr->status = DASD_CQR_CLEARED;

		cqr->status = DASD_CQR_CLEARED;

		if (cqr->callback_data == DASD_SLEEPON_START_TAG)

			cqr->callback_data = DASD_SLEEPON_END_TAG;

		break;

		break;

	case DASD_CQR_IN_IO:

	case DASD_CQR_IN_IO:

		/* request in IO - terminate IO and release again */

		/* request in IO - terminate IO and release again */
@@ -3902,9 +3900,12 @@ static int dasd_generic_requeue_all_requests(struct dasd_device *device) 
		wait_event(dasd_flush_wq,

		wait_event(dasd_flush_wq,

			   (cqr->status != DASD_CQR_CLEAR_PENDING));

			   (cqr->status != DASD_CQR_CLEAR_PENDING));





		/* mark sleepon requests as ended */

		/*

		if (cqr->callback_data == DASD_SLEEPON_START_TAG)

		 * requeue requests to blocklayer will only work

			cqr->callback_data = DASD_SLEEPON_END_TAG;

		 * for block device requests

		 */

		if (_dasd_requeue_request(cqr))

			continue;





		/* remove requests from device and block queue */

		/* remove requests from device and block queue */

		list_del_init(&cqr->devlist);

		list_del_init(&cqr->devlist);
@@ -3917,13 +3918,6 @@ static int dasd_generic_requeue_all_requests(struct dasd_device *device) 
			cqr = refers;

			cqr = refers;

		}

		}





		/*

		 * requeue requests to blocklayer will only work

		 * for block device requests

		 */

		if (_dasd_requeue_request(cqr))

			continue;



		if (cqr->block)

		if (cqr->block)

			list_del_init(&cqr->blocklist);

			list_del_init(&cqr->blocklist);

		cqr->block->base->discipline->free_cp(

		cqr->block->base->discipline->free_cp(
@@ -3940,8 +3934,7 @@ static int dasd_generic_requeue_all_requests(struct dasd_device *device) 
		list_splice_tail(&requeue_queue, &device->ccw_queue);

		list_splice_tail(&requeue_queue, &device->ccw_queue);

		spin_unlock_irq(get_ccwdev_lock(device->cdev));

		spin_unlock_irq(get_ccwdev_lock(device->cdev));

	}

	}

	/* wake up generic waitqueue for eventually ended sleepon requests */

	dasd_schedule_device_bh(device);

	wake_up(&generic_waitq);

	return rc;

	return rc;

}

}