drbd: mutex_unlock "... must no be used in interrupt context"

Documentation of mutex_unlock says
we must not use it in interrupt context.
So do not call it while holding the spin_lock_irq,
but give up the spinlock temporarily.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 39 insertions, 35 deletions

diff --git a/drivers/block/drbd/drbd_state.c b/drivers/block/drbd/drbd_state.c
index ce1495187f02..755425a7a99b 100644
--- a/drivers/block/drbd/drbd_state.c
+++ b/drivers/block/drbd/drbd_state.c
@@ -1721,38 +1721,6 @@ _conn_rq_cond(struct drbd_tconn *tconn, union drbd_state mask, union drbd_state
         return rv;
 }
 
-static enum drbd_state_rv
-conn_cl_wide(struct drbd_tconn *tconn, union drbd_state mask, union drbd_state val,
-             enum chg_state_flags f)
-{
-        enum drbd_state_rv rv;
-
-        spin_unlock_irq(&tconn->req_lock);
-        mutex_lock(&tconn->cstate_mutex);
-
-        set_bit(CONN_WD_ST_CHG_REQ, &tconn->flags);
-        if (conn_send_state_req(tconn, mask, val)) {
-                clear_bit(CONN_WD_ST_CHG_REQ, &tconn->flags);
-                /* if (f & CS_VERBOSE)
-                   print_st_err(mdev, os, ns, rv); */
-                mutex_unlock(&tconn->cstate_mutex);
-                spin_lock_irq(&tconn->req_lock);
-                return SS_CW_FAILED_BY_PEER;
-        }
-
-        if (val.conn == C_DISCONNECTING)
-                set_bit(DISCONNECT_SENT, &tconn->flags);
-
-        spin_lock_irq(&tconn->req_lock);
-
-        wait_event_lock_irq(tconn->ping_wait, (rv = _conn_rq_cond(tconn, mask, val)), tconn->req_lock,);
-        clear_bit(CONN_WD_ST_CHG_REQ, &tconn->flags);
-
-        mutex_unlock(&tconn->cstate_mutex);
-
-        return rv;
-}
-
 enum drbd_state_rv
 _conn_request_state(struct drbd_tconn *tconn, union drbd_state mask, union drbd_state val,
                     enum chg_state_flags flags)
@@ -1761,6 +1729,7 @@ _conn_request_state(struct drbd_tconn *tconn, union drbd_state mask, union drbd_
         struct after_conn_state_chg_work *acscw;
         enum drbd_conns oc = tconn->cstate;
         union drbd_state ns_max, ns_min, os;
+        bool have_mutex = false;
 
         rv = is_valid_conn_transition(oc, val.conn);
         if (rv < SS_SUCCESS)
@@ -1772,7 +1741,35 @@ _conn_request_state(struct drbd_tconn *tconn, union drbd_state mask, union drbd_
 
         if (oc == C_WF_REPORT_PARAMS && val.conn == C_DISCONNECTING &&
             !(flags & (CS_LOCAL_ONLY | CS_HARD))) {
-                rv = conn_cl_wide(tconn, mask, val, flags);
+
+                /* This will be a cluster-wide state change.
+                 * Need to give up the spinlock, grab the mutex,
+                 * then send the state change request, ... */
+                spin_unlock_irq(&tconn->req_lock);
+                mutex_lock(&tconn->cstate_mutex);
+                have_mutex = true;
+
+                set_bit(CONN_WD_ST_CHG_REQ, &tconn->flags);
+                if (conn_send_state_req(tconn, mask, val)) {
+                        /* sending failed. */
+                        clear_bit(CONN_WD_ST_CHG_REQ, &tconn->flags);
+                        rv = SS_CW_FAILED_BY_PEER;
+                        /* need to re-aquire the spin lock, though */
+                        goto abort_unlocked;
+                }
+
+                if (val.conn == C_DISCONNECTING)
+                        set_bit(DISCONNECT_SENT, &tconn->flags);
+
+                /* ... and re-aquire the spinlock.
+                 * If _conn_rq_cond() returned >= SS_SUCCESS, we must call
+                 * conn_set_state() within the same spinlock. */
+                spin_lock_irq(&tconn->req_lock);
+                wait_event_lock_irq(tconn->ping_wait,
+                                (rv = _conn_rq_cond(tconn, mask, val)),
+                                tconn->req_lock,
+                                );
+                clear_bit(CONN_WD_ST_CHG_REQ, &tconn->flags);
                 if (rv < SS_SUCCESS)
                         goto abort;
         }
@@ -1796,9 +1793,16 @@ _conn_request_state(struct drbd_tconn *tconn, union drbd_state mask, union drbd_
                 conn_err(tconn, "Could not kmalloc an acscw\n");
         }
 
-        return rv;
  abort:
-        if (flags & CS_VERBOSE) {
+        if (have_mutex) {
+                /* mutex_unlock() "... must not be used in interrupt context.",
+                 * so give up the spinlock, then re-aquire it */
+                spin_unlock_irq(&tconn->req_lock);
+ abort_unlocked:
+                mutex_unlock(&tconn->cstate_mutex);
+                spin_lock_irq(&tconn->req_lock);
+        }
+        if (rv < SS_SUCCESS && flags & CS_VERBOSE) {
                 conn_err(tconn, "State change failed: %s\n", drbd_set_st_err_str(rv));
                 conn_err(tconn, " state = { cs:%s }\n", drbd_conn_str(oc));
                 conn_err(tconn, "wanted = { cs:%s }\n", drbd_conn_str(val.conn));