diff options
| author | Philipp Reisner <philipp.reisner@linbit.com> | 2014-04-28 20:43:12 +0400 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2014-04-30 23:46:53 +0400 |
| commit | 31007745a5f328b8d70d865c4a6118be01421b8c (patch) | |
| tree | f3ac7edd14a10da7b11820bcf2be3639ac4d44cf | |
| parent | d1e714db8129a1d3670e449b87719c78e2c76f9f (diff) | |
| download | linux-31007745a5f328b8d70d865c4a6118be01421b8c.tar.xz | |
drbd: Break a deadlock while concurrent fencing and establishing a connection
When we need to outdate the peer while being promoted to primary,
and the connection gets established at the same time, we deadlock
in drbd_try_outdate_peer() when trying to clear the susp_fen
bit.
Fix this by setting the STATE_SENT bit while holding the mutex.
Using drbd_change_state(.. , CS_HARD, ..) which does not block
until STATE_SENT is cleared, is only for clearness. It does
not contribute anything to the fix.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
| -rw-r--r-- | drivers/block/drbd/drbd_receiver.c | 23 |
1 files changed, 13 insertions, 10 deletions
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c index 68e3992e8838..125c9e89388f 100644 --- a/drivers/block/drbd/drbd_receiver.c +++ b/drivers/block/drbd/drbd_receiver.c @@ -1026,24 +1026,27 @@ randomize: if (drbd_send_protocol(connection) == -EOPNOTSUPP) return -1; + /* Prevent a race between resync-handshake and + * being promoted to Primary. + * + * Grab and release the state mutex, so we know that any current + * drbd_set_role() is finished, and any incoming drbd_set_role + * will see the STATE_SENT flag, and wait for it to be cleared. + */ + idr_for_each_entry(&connection->peer_devices, peer_device, vnr) + mutex_lock(peer_device->device->state_mutex); + set_bit(STATE_SENT, &connection->flags); + idr_for_each_entry(&connection->peer_devices, peer_device, vnr) + mutex_unlock(peer_device->device->state_mutex); + rcu_read_lock(); idr_for_each_entry(&connection->peer_devices, peer_device, vnr) { struct drbd_device *device = peer_device->device; kref_get(&device->kref); rcu_read_unlock(); - /* Prevent a race between resync-handshake and - * being promoted to Primary. - * - * Grab and release the state mutex, so we know that any current - * drbd_set_role() is finished, and any incoming drbd_set_role - * will see the STATE_SENT flag, and wait for it to be cleared. - */ - mutex_lock(device->state_mutex); - mutex_unlock(device->state_mutex); - if (discard_my_data) set_bit(DISCARD_MY_DATA, &device->flags); else |