drbd: fix race when forcefully disconnecting

If a forced disconnect hits a restarting receiver right after it passed
its final "if (C_DISCONNECTING)" test in drbdd_init(), but before it was
actually restarted by drbd_thread_setup, we could be left with a
connection stuck in C_DISCONNECTING, never reaching C_STANDALONE,
which would be necessary to take it down or reconfigure it.

Move the last cleanup into w_after_conn_state_ch(), and do an additional
state change request in conn_try_disconnect(), just in case.

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 2011-05-02 10:45:05 +02:00 committed by Philipp Reisner
parent 88104ca458
commit f3dfa40a67
3 changed files with 62 additions and 50 deletions

View File

@ -2115,37 +2115,54 @@ out:
static enum drbd_state_rv conn_try_disconnect(struct drbd_tconn *tconn, bool force)
{
enum drbd_state_rv rv;
if (force) {
spin_lock_irq(&tconn->req_lock);
rv = _conn_request_state(tconn, NS(conn, C_DISCONNECTING), CS_HARD);
spin_unlock_irq(&tconn->req_lock);
return rv;
}
rv = conn_request_state(tconn, NS(conn, C_DISCONNECTING), 0);
rv = conn_request_state(tconn, NS(conn, C_DISCONNECTING),
force ? CS_HARD : 0);
switch (rv) {
case SS_NOTHING_TO_DO:
break;
case SS_ALREADY_STANDALONE:
return SS_SUCCESS;
case SS_PRIMARY_NOP:
/* Our state checking code wants to see the peer outdated. */
rv = conn_request_state(tconn, NS2(conn, C_DISCONNECTING,
pdsk, D_OUTDATED), CS_VERBOSE);
pdsk, D_OUTDATED), CS_VERBOSE);
break;
case SS_CW_FAILED_BY_PEER:
/* The peer probably wants to see us outdated. */
rv = conn_request_state(tconn, NS2(conn, C_DISCONNECTING,
disk, D_OUTDATED), 0);
if (rv == SS_IS_DISKLESS || rv == SS_LOWER_THAN_OUTDATED) {
conn_request_state(tconn, NS(conn, C_DISCONNECTING), CS_HARD);
rv = SS_SUCCESS;
rv = conn_request_state(tconn, NS(conn, C_DISCONNECTING),
CS_HARD);
}
break;
default:;
/* no special handling necessary */
}
if (rv >= SS_SUCCESS) {
enum drbd_state_rv rv2;
/* No one else can reconfigure the network while I am here.
* The state handling only uses drbd_thread_stop_nowait(),
* we want to really wait here until the receiver is no more.
*/
drbd_thread_stop(&adm_ctx.tconn->receiver);
/* Race breaker. This additional state change request may be
* necessary, if this was a forced disconnect during a receiver
* restart. We may have "killed" the receiver thread just
* after drbdd_init() returned. Typically, we should be
* C_STANDALONE already, now, and this becomes a no-op.
*/
rv2 = conn_request_state(tconn, NS(conn, C_STANDALONE),
CS_VERBOSE | CS_HARD);
if (rv2 < SS_SUCCESS)
conn_err(tconn,
"unexpected rv2=%d in conn_try_disconnect()\n",
rv2);
}
return rv;
}
@ -2176,19 +2193,9 @@ int drbd_adm_disconnect(struct sk_buff *skb, struct genl_info *info)
rv = conn_try_disconnect(tconn, parms.force_disconnect);
if (rv < SS_SUCCESS)
goto fail;
/* No one else can reconfigure the network while I am here.
* The state handling only uses drbd_thread_stop_nowait(),
* we want to really wait here until the receiver is no more. */
drbd_thread_stop(&tconn->receiver);
if (wait_event_interruptible(tconn->ping_wait,
tconn->cstate == C_STANDALONE)) {
retcode = ERR_INTR;
goto fail;
}
retcode = NO_ERROR;
retcode = rv; /* FIXME: Type mismatch. */
else
retcode = NO_ERROR;
fail:
drbd_adm_finish(info, retcode);
return 0;
@ -3049,8 +3056,7 @@ out:
int drbd_adm_down(struct sk_buff *skb, struct genl_info *info)
{
enum drbd_ret_code retcode;
enum drbd_state_rv rv;
int retcode; /* enum drbd_ret_code rsp. enum drbd_state_rv */
struct drbd_conf *mdev;
unsigned i;
@ -3074,30 +3080,35 @@ int drbd_adm_down(struct sk_buff *skb, struct genl_info *info)
goto out_unlock;
}
}
up_read(&drbd_cfg_rwsem);
/* disconnect */
rv = conn_try_disconnect(adm_ctx.tconn, 0);
if (rv < SS_SUCCESS) {
retcode = rv; /* enum type mismatch! */
/* disconnect; may stop the receiver;
* must not hold the drbd_cfg_rwsem */
retcode = conn_try_disconnect(adm_ctx.tconn, 0);
if (retcode < SS_SUCCESS) {
drbd_msg_put_info("failed to disconnect");
goto out_unlock;
goto out;
}
/* Make sure the network threads have actually stopped,
* state handling only does drbd_thread_stop_nowait(). */
drbd_thread_stop(&adm_ctx.tconn->receiver);
down_read(&drbd_cfg_rwsem);
/* detach */
idr_for_each_entry(&adm_ctx.tconn->volumes, mdev, i) {
rv = adm_detach(mdev);
if (rv < SS_SUCCESS) {
retcode = rv; /* enum type mismatch! */
retcode = adm_detach(mdev);
if (retcode < SS_SUCCESS) {
drbd_msg_put_info("failed to detach");
goto out_unlock;
}
}
up_read(&drbd_cfg_rwsem);
/* If we reach this, all volumes (of this tconn) are Secondary,
* Disconnected, Diskless, aka Unconfigured. Make sure all threads have
* actually stopped, state handling only does drbd_thread_stop_nowait().
* This needs to be done without holding drbd_cfg_rwsem. */
drbd_thread_stop(&adm_ctx.tconn->worker);
/* Now, nothing can fail anymore */
/* delete volumes */
down_write(&drbd_cfg_rwsem);
idr_for_each_entry(&adm_ctx.tconn->volumes, mdev, i) {

View File

@ -4213,20 +4213,8 @@ static void drbd_disconnect(struct drbd_tconn *tconn)
spin_unlock_irq(&tconn->req_lock);
if (oc == C_DISCONNECTING) {
struct net_conf *old_conf;
mutex_lock(&tconn->net_conf_update);
old_conf = tconn->net_conf;
rcu_assign_pointer(tconn->net_conf, NULL);
conn_free_crypto(tconn);
mutex_unlock(&tconn->net_conf_update);
synchronize_rcu();
kfree(old_conf);
if (oc == C_DISCONNECTING)
conn_request_state(tconn, NS(conn, C_STANDALONE), CS_VERBOSE | CS_HARD);
}
}
static int drbd_disconnected(int vnr, void *p, void *data)

View File

@ -1416,6 +1416,19 @@ static int w_after_conn_state_ch(struct drbd_work *w, int unused)
if (oc == C_STANDALONE && ns_max.conn == C_UNCONNECTED)
drbd_thread_start(&tconn->receiver);
if (oc == C_DISCONNECTING && ns_max.conn == C_STANDALONE) {
struct net_conf *old_conf;
mutex_lock(&tconn->net_conf_update);
old_conf = tconn->net_conf;
rcu_assign_pointer(tconn->net_conf, NULL);
conn_free_crypto(tconn);
mutex_unlock(&tconn->net_conf_update);
synchronize_rcu();
kfree(old_conf);
}
if (ns_max.susp_fen) {
/* case1: The outdate peer handler is successful: */
if (ns_max.pdsk <= D_OUTDATED) {