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s390/qeth: fix deadlock during failing recovery 

Commit 0b9902c1fc ("s390/qeth: fix deadlock during recovery") removed
taking discipline_mutex inside qeth_do_reset(), fixing potential
deadlocks. An error path was missed though, that still takes
discipline_mutex and thus has the original deadlock potential.

Intermittent deadlocks were seen when a qeth channel path is configured
offline, causing a race between qeth_do_reset and ccwgroup_remove.
Call qeth_set_offline() directly in the qeth_do_reset() error case and
then a new variant of ccwgroup_set_offline(), without taking
discipline_mutex.

Fixes: b41b554c1e ("s390/qeth: fix locking for discipline setup / removal")
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Alexandra Winter 2021-09-21 16:52:17 +02:00 committed by Jakub Kicinski
parent ee909d0b1d
commit d2b59bd4b0
3 changed files with 11 additions and 4 deletions
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2
arch/s390/include/asm/ccwgroup.h
View File

@ -55,7 +55,7 @@ int ccwgroup_create_dev(struct device *root, struct ccwgroup_driver *gdrv,
int num_devices, const char *buf);
extern int ccwgroup_set_online(struct ccwgroup_device *gdev);
extern int ccwgroup_set_offline(struct ccwgroup_device *gdev);
int ccwgroup_set_offline(struct ccwgroup_device *gdev, bool call_gdrv);
extern int ccwgroup_probe_ccwdev(struct ccw_device *cdev);
extern void ccwgroup_remove_ccwdev(struct ccw_device *cdev);

10
drivers/s390/cio/ccwgroup.c
View File

@ -77,12 +77,13 @@ EXPORT_SYMBOL(ccwgroup_set_online);
/**
* ccwgroup_set_offline() - disable a ccwgroup device
* @gdev: target ccwgroup device
* @call_gdrv: Call the registered gdrv set_offline function
*
* This function attempts to put the ccwgroup device into the offline state.
* Returns:
* %0 on success and a negative error value on failure.
*/
int ccwgroup_set_offline(struct ccwgroup_device *gdev)
int ccwgroup_set_offline(struct ccwgroup_device *gdev, bool call_gdrv)
{
struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
int ret = -EINVAL;
@ -91,11 +92,16 @@ int ccwgroup_set_offline(struct ccwgroup_device *gdev)
return -EAGAIN;
if (gdev->state == CCWGROUP_OFFLINE)
goto out;
if (!call_gdrv) {
ret = 0;
goto offline;
}
if (gdrv->set_offline)
ret = gdrv->set_offline(gdev);
if (ret)
goto out;
offline:
gdev->state = CCWGROUP_OFFLINE;
out:
atomic_set(&gdev->onoff, 0);
@ -124,7 +130,7 @@ static ssize_t ccwgroup_online_store(struct device *dev,
if (value == 1)
ret = ccwgroup_set_online(gdev);
else if (value == 0)
ret = ccwgroup_set_offline(gdev);
ret = ccwgroup_set_offline(gdev, true);
else
ret = -EINVAL;
out:

3
drivers/s390/net/qeth_core_main.c
View File

@ -5514,7 +5514,8 @@ static int qeth_do_reset(void *data)
dev_info(&card->gdev->dev,
"Device successfully recovered!\n");
} else {
ccwgroup_set_offline(card->gdev);
qeth_set_offline(card, disc, true);
ccwgroup_set_offline(card->gdev, false);
dev_warn(&card->gdev->dev,
"The qeth device driver failed to recover an error on the device\n");
}