[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: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index ab35217..0be7c15 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -2338,6 +2338,8 @@
/* Calculate number of blocks/records per track. */
blksize = block->bp_block;
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. */
first_rec = first_trk = blk_rq_pos(req) >> block->s2b_shift;
first_offs = sector_div(first_trk, blk_per_trk);
@@ -3211,6 +3213,7 @@
int dasd_eckd_restore_device(struct dasd_device *device)
{
struct dasd_eckd_private *private;
+ struct dasd_eckd_characteristics temp_rdc_data;
int is_known, rc;
struct dasd_uid temp_uid;
@@ -3245,15 +3248,17 @@
dasd_eckd_read_features(device);
/* Read Device Characteristics */
- memset(&private->rdc_data, 0, sizeof(private->rdc_data));
rc = dasd_generic_read_dev_chars(device, DASD_ECKD_MAGIC,
- &private->rdc_data, 64);
+ &temp_rdc_data, 64);
if (rc) {
DBF_EVENT(DBF_WARNING,
"Read device characteristics failed, rc=%d for "
"device: %s", rc, dev_name(&device->cdev->dev));
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 */
dasd_alias_add_device(device);