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drbd: fix race between deconfiguring and reconfiguring network 

If a drbd_nl_net_conf hits the small window between the state change
to C_STANDALONE and the corresponding cleanup in after_state_ch,
that cleanup would throw away stuff we now need again,
and later trigger BUG_ON()s.

Fixed by properly serializing the new config request with
any pending cleanup.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Lars Ellenberg 2010-09-01 09:50:23 +02:00 committed by Philipp Reisner
parent 0778286a13
commit c518d04fde
1 changed files with 4 additions and 2 deletions
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6
drivers/block/drbd/drbd_nl.c
View File

@ -750,14 +750,16 @@ void drbd_setup_queue_param(struct drbd_conf *mdev, unsigned int max_seg_s) __mu
/* serialize deconfig (worker exiting, doing cleanup)
* and reconfig (drbdsetup disk, drbdsetup net)
*
* wait for a potentially exiting worker, then restart it,
* or start a new one.
* Wait for a potentially exiting worker, then restart it,
* or start a new one. Flush any pending work, there may still be an
* after_state_change queued.
*/
static void drbd_reconfig_start(struct drbd_conf *mdev)
{
wait_event(mdev->state_wait, !test_and_set_bit(CONFIG_PENDING, &mdev->flags));
wait_event(mdev->state_wait, !test_bit(DEVICE_DYING, &mdev->flags));
drbd_thread_start(&mdev->worker);
drbd_flush_workqueue(mdev);
}
/* if still unconfigured, stops worker again.