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| author | Philipp Reisner <philipp.reisner@linbit.com> | 2010-06-02 14:31:29 +0200 |
|---|---|---|
| committer | Philipp Reisner <philipp.reisner@linbit.com> | 2010-06-14 12:19:41 +0200 |
| commit | dc66c74de6f4238020db3e2041d4aca5c5b3e9bc (patch) | |
| tree | 8df9cdd2f1672217a210e624f4613744e57450e0 /drivers/block | |
| parent | Linux 2.6.35-rc3 (diff) | |
| download | linux-dc66c74de6f4238020db3e2041d4aca5c5b3e9bc.tar.xz linux-dc66c74de6f4238020db3e2041d4aca5c5b3e9bc.zip | |
drbd: Fixed a race between disk-attach and unexpected state changes
This was a very hard to trigger race condition.
If we got a state packet from the peer, after drbd_nl_disk() has
already changed the disk state to D_NEGOTIATING but
after_state_ch() was not yet run by the worker, then receive_state()
might called drbd_sync_handshake(), which in turn crashed
when accessing p_uuid.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/drbd/drbd_main.c | 2 | ||||
| -rw-r--r-- | drivers/block/drbd/drbd_nl.c | 6 |
2 files changed, 6 insertions, 2 deletions
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c index 6b077f93acc6..7258c95e895e 100644 --- a/drivers/block/drbd/drbd_main.c +++ b/drivers/block/drbd/drbd_main.c @@ -1236,8 +1236,6 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os, /* Last part of the attaching process ... */ if (ns.conn >= C_CONNECTED && os.disk == D_ATTACHING && ns.disk == D_NEGOTIATING) { - kfree(mdev->p_uuid); /* We expect to receive up-to-date UUIDs soon. */ - mdev->p_uuid = NULL; /* ...to not use the old ones in the mean time */ drbd_send_sizes(mdev, 0, 0); /* to start sync... */ drbd_send_uuids(mdev); drbd_send_state(mdev); diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c index 632e3245d1bb..2151f18b21de 100644 --- a/drivers/block/drbd/drbd_nl.c +++ b/drivers/block/drbd/drbd_nl.c @@ -1114,6 +1114,12 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp mdev->new_state_tmp.i = ns.i; ns.i = os.i; ns.disk = D_NEGOTIATING; + + /* We expect to receive up-to-date UUIDs soon. + To avoid a race in receive_state, free p_uuid while + holding req_lock. I.e. atomic with the state change */ + kfree(mdev->p_uuid); + mdev->p_uuid = NULL; } rv = _drbd_set_state(mdev, ns, CS_VERBOSE, NULL); |