drbd: Fixed a deadlock, probably only affected UP machines

After disconnect (most likely mdev->net_cnt == 0) and we are
still in an unstable state (!drbd_state_is_stable()). When we
get an IO request in drbd_get_max_buffers() (called from
__inc_ap_bio_cond(), called from inc_ap_bio()) we wake up
misc_wait. Misc_wait is also used in inc_ap_bio() to sleep
until the outcome of __inc_ap_bio_cond() changes. => Busy loop!

Solution: Have a dedicated wait queue for get_net_conf() and
put_net_conf().

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Philipp Reisner
2010-06-23 11:20:05 +02:00
parent 65d922c33e
commit 84dfb9f564
3 changed files with 4 additions and 2 deletions
+1
View File
@@ -2763,6 +2763,7 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
init_waitqueue_head(&mdev->misc_wait);
init_waitqueue_head(&mdev->state_wait);
init_waitqueue_head(&mdev->net_cnt_wait);
init_waitqueue_head(&mdev->ee_wait);
init_waitqueue_head(&mdev->al_wait);
init_waitqueue_head(&mdev->seq_wait);