Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 6fca97a9 authored by Stefan Haberland's avatar Stefan Haberland Committed by Martin Schwidefsky
Browse files

[S390] dasd: fix race condition in resume code 



There is a race while re-reading the device characteristics. After
cleaning the memory area a cqr is build which reads the device
characteristics. This may take a rather long time and the device
characteristics structure is zero during this. Now it could be
possible that the block tasklet starts working and a new cqr will be
build. The build_cp command refers to the device characteristics
structure and this may lead into a divide by zero exception.
Fix this by re-reading the device characteristics into a temporary
structur and copy the data to the original structure. Also take the
ccwdev_lock.

Signed-off-by: default avatarStefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent af9d2ff9

drivers/s390/block/dasd.c

+3 −2
Original line number Original line Diff line number Diff line
@@ -2508,8 +2508,6 @@ int dasd_generic_restore_device(struct ccw_device *cdev) 
	device->stopped &= ~DASD_UNRESUMED_PM;

	device->stopped &= ~DASD_UNRESUMED_PM;





	dasd_schedule_device_bh(device);

	dasd_schedule_device_bh(device);

	if (device->block)

		dasd_schedule_block_bh(device->block);





	if (device->discipline->restore)

	if (device->discipline->restore)

		rc = device->discipline->restore(device);

		rc = device->discipline->restore(device);
@@ -2520,6 +2518,9 @@ int dasd_generic_restore_device(struct ccw_device *cdev) 
		 */

		 */

		device->stopped |= DASD_UNRESUMED_PM;

		device->stopped |= DASD_UNRESUMED_PM;





	if (device->block)

		dasd_schedule_block_bh(device->block);



	dasd_put_device(device);

	dasd_put_device(device);

	return 0;

	return 0;

}

}

drivers/s390/block/dasd_eckd.c

+7 −2
Original line number Original line Diff line number Diff line
@@ -2338,6 +2338,8 @@ static struct dasd_ccw_req *dasd_eckd_build_cp(struct dasd_device *startdev, 
	/* Calculate number of blocks/records per track. */

	/* Calculate number of blocks/records per track. */

	blksize = block->bp_block;

	blksize = block->bp_block;

	blk_per_trk = recs_per_track(&private->rdc_data, 0, blksize);

	blk_per_trk = recs_per_track(&private->rdc_data, 0, blksize);

	if (blk_per_trk == 0)

		return ERR_PTR(-EINVAL);

	/* Calculate record id of first and last block. */

	/* Calculate record id of first and last block. */

	first_rec = first_trk = blk_rq_pos(req) >> block->s2b_shift;

	first_rec = first_trk = blk_rq_pos(req) >> block->s2b_shift;

	first_offs = sector_div(first_trk, blk_per_trk);

	first_offs = sector_div(first_trk, blk_per_trk);
@@ -3211,6 +3213,7 @@ int dasd_eckd_pm_freeze(struct dasd_device *device) 
int dasd_eckd_restore_device(struct dasd_device *device)

int dasd_eckd_restore_device(struct dasd_device *device)

{

{

	struct dasd_eckd_private *private;

	struct dasd_eckd_private *private;

	struct dasd_eckd_characteristics temp_rdc_data;

	int is_known, rc;

	int is_known, rc;

	struct dasd_uid temp_uid;

	struct dasd_uid temp_uid;
@@ -3245,15 +3248,17 @@ int dasd_eckd_restore_device(struct dasd_device *device) 
	dasd_eckd_read_features(device);

	dasd_eckd_read_features(device);





	/* Read Device Characteristics */

	/* Read Device Characteristics */

	memset(&private->rdc_data, 0, sizeof(private->rdc_data));

	rc = dasd_generic_read_dev_chars(device, DASD_ECKD_MAGIC,

	rc = dasd_generic_read_dev_chars(device, DASD_ECKD_MAGIC,

					 &private->rdc_data, 64);

					 &temp_rdc_data, 64);

	if (rc) {

	if (rc) {

		DBF_EVENT(DBF_WARNING,

		DBF_EVENT(DBF_WARNING,

			  "Read device characteristics failed, rc=%d for "

			  "Read device characteristics failed, rc=%d for "

			  "device: %s", rc, dev_name(&device->cdev->dev));

			  "device: %s", rc, dev_name(&device->cdev->dev));

		goto out_err;

		goto out_err;

	}

	}

	spin_lock(get_ccwdev_lock(device->cdev));

	memcpy(&private->rdc_data, &temp_rdc_data, sizeof(temp_rdc_data));

	spin_unlock(get_ccwdev_lock(device->cdev));





	/* add device to alias management */

	/* add device to alias management */

	dasd_alias_add_device(device);

	dasd_alias_add_device(device);