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s390/dasd: prevent inconsistent LCU device data

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commit a29ea01653493b94ea12bb2b89d1564a265081b6 upstream.

Prevent _lcu_update from adding a device to a pavgroup if the LCU still
requires an update. The data is not reliable any longer and in parallel
devices might have been moved on the lists already.
This might lead to list corruptions or invalid PAV grouping.
Only add devices to a pavgroup if the LCU is up to date. Additional steps
are taken by the scheduled lcu update.

Fixes: 8e09f21574 ("[S390] dasd: add hyper PAV support to DASD device driver, part 1")
Cc: stable@vger.kernel.org
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Stefan Haberland 2020-12-17 16:59:05 +01:00 committed by Greg Kroah-Hartman
parent a67e261b5b
commit 96aca84128
1 changed files with 9 additions and 0 deletions
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9
drivers/s390/block/dasd_alias.c
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@ -511,6 +511,14 @@ static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
return rc;
spin_lock_irqsave(&lcu->lock, flags);
/*
* there is another update needed skip the remaining handling
* the data might already be outdated
* but especially do not add the device to an LCU with pending
* update
*/
if (lcu->flags & NEED_UAC_UPDATE)
goto out;
lcu->pav = NO_PAV;
for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
switch (lcu->uac->unit[i].ua_type) {
@ -529,6 +537,7 @@ static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
alias_list) {
_add_device_to_lcu(lcu, device, refdev);
}
out:
spin_unlock_irqrestore(&lcu->lock, flags);
return 0;
}