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| author | Julian Wiedmann <jwi@linux.ibm.com> | 2021-01-07 20:24:40 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-01-17 16:16:58 +0300 |
| commit | 1214d69a2bfcc49c2be3185be23aa828724269cb (patch) | |
| tree | 67a2c8fc1c754c544c5dd33d4d562e6e3811758b /drivers/s390/net/qeth_l3_main.c | |
| parent | 5fb8a3116cd0a439e2be2559b2feb22fd2c06092 (diff) | |
| download | linux-1214d69a2bfcc49c2be3185be23aa828724269cb.tar.xz | |
s390/qeth: fix deadlock during recovery
[ Upstream commit 0b9902c1fcc59ba75268386c0420a554f8844168 ]
When qeth_dev_layer2_store() - holding the discipline_mutex - waits
inside qeth_l*_remove_device() for a qeth_do_reset() thread to complete,
we can hit a deadlock if qeth_do_reset() concurrently calls
qeth_set_online() and thus tries to aquire the discipline_mutex.
Move the discipline_mutex locking outside of qeth_set_online() and
qeth_set_offline(), and turn the discipline into a parameter so that
callers understand the dependency.
To fix the deadlock, we can now relax the locking:
As already established, qeth_l*_remove_device() waits for
qeth_do_reset() to complete. So qeth_do_reset() itself is under no risk
of having card->discipline ripped out while it's running, and thus
doesn't need to take the discipline_mutex.
Fixes: 9dc48ccc68b9 ("qeth: serialize sysfs-triggered device configurations")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/s390/net/qeth_l3_main.c')
| -rw-r--r-- | drivers/s390/net/qeth_l3_main.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c index b1c1d2510d55..fa28a39d0cb7 100644 --- a/drivers/s390/net/qeth_l3_main.c +++ b/drivers/s390/net/qeth_l3_main.c @@ -1973,8 +1973,11 @@ static void qeth_l3_remove_device(struct ccwgroup_device *cgdev) qeth_set_allowed_threads(card, 0, 1); wait_event(card->wait_q, qeth_threads_running(card, 0xffffffff) == 0); - if (cgdev->state == CCWGROUP_ONLINE) - qeth_set_offline(card, false); + if (cgdev->state == CCWGROUP_ONLINE) { + mutex_lock(&card->discipline_mutex); + qeth_set_offline(card, card->discipline, false); + mutex_unlock(&card->discipline_mutex); + } cancel_work_sync(&card->close_dev_work); if (card->dev->reg_state == NETREG_REGISTERED) |