ib_srpt: Fix "rejected SRP_LOGIN_REQ because creating a new RDMA channel failed"

Fix two race conditions that could trigger this failure:
- Completion thread not woken up after channel state change.
- Reception of Last WQE event before the channel queue pair was reset.


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@3870 d57e44dd-8a1f-0410-8b47-8ef2f437770f

srpt/src/ib_srpt.c

@@ -164,6 +164,9 @@ srpt_set_ch_state(struct srpt_rdma_ch *ch, enum rdma_ch_state new_state)
 	prev = ch->state;
 	ch->state = new_state;
 	spin_unlock_irqrestore(&ch->spinlock, flags);
+
+	if (prev != new_state)
+		wake_up_process(ch->thread);
 	return prev;
 }
 
@@ -171,6 +174,7 @@ static enum rdma_ch_state srpt_set_ch_state_to_disc(struct srpt_rdma_ch *ch)
 {
 	unsigned long flags;
 	enum rdma_ch_state prev;
+	bool changed = false;
 
 	spin_lock_irqsave(&ch->spinlock, flags);
 	prev = ch->state;
@@ -178,19 +182,23 @@ static enum rdma_ch_state srpt_set_ch_state_to_disc(struct srpt_rdma_ch *ch)
 	case CH_CONNECTING:
 	case CH_LIVE:
 		ch->state = CH_DISCONNECTING;
+		changed = true;
 		break;
 	default:
 		break;
 	}
 	spin_unlock_irqrestore(&ch->spinlock, flags);
 
+	if (changed)
+		wake_up_process(ch->thread);
+
 	return prev;
 }
 
 static bool srpt_set_ch_state_to_draining(struct srpt_rdma_ch *ch)
 {
 	unsigned long flags;
-	bool changed_state = false;
+	bool changed = false;
 
 	spin_lock_irqsave(&ch->spinlock, flags);
 	switch (ch->state) {
@@ -198,14 +206,16 @@ static bool srpt_set_ch_state_to_draining(struct srpt_rdma_ch *ch)
 	case CH_LIVE:
 	case CH_DISCONNECTING:
 		ch->state = CH_DRAINING;
-		changed_state = true;
+		changed = true;
 		break;
 	default:
 		break;
 	}
 	spin_unlock_irqrestore(&ch->spinlock, flags);
 
-	return changed_state;
+	if (changed)
+		wake_up_process(ch->thread);
+	return changed;
 }
 
 /**
@@ -228,7 +238,7 @@ static bool srpt_test_and_set_ch_state(struct srpt_rdma_ch *ch,
 	spin_unlock_irqrestore(&ch->spinlock, flags);
 
 	if (changed)
-		wake_up(&ch->state_wq);
+		wake_up_process(ch->thread);
 	return changed;
 }
 
@@ -375,9 +385,10 @@ static void srpt_qp_event(struct ib_event *event, struct srpt_rdma_ch *ch)
 #endif
 		break;
 	case IB_EVENT_QP_LAST_WQE_REACHED:
-		if (!srpt_test_and_set_ch_state(ch, CH_DRAINING, CH_RELEASING))
-			TRACE_DBG("%s: state %s - ignored Last WQE event.",
-				  ch->sess_name, get_ch_state_name(ch->state));
+		TRACE_DBG("%s, state %s: received Last WQE event.",
+			  ch->sess_name, get_ch_state_name(ch->state));
+		ch->last_wqe_received = true;
+		srpt_test_and_set_ch_state(ch, CH_DRAINING, CH_RELEASING);
 		break;
 	default:
 		PRINT_ERROR("received unrecognized IB QP event %d",
@@ -2178,7 +2189,6 @@ static bool __srpt_close_ch(struct srpt_rdma_ch *ch)
 		/* fall through */
 	case CH_LIVE:
 		was_live = true;
-		wake_up_process(ch->thread);
 		if (ib_send_cm_dreq(ch->cm_id, NULL, 0) < 0)
 			PRINT_ERROR("sending CM DREQ failed.");
 		break;
@@ -2229,9 +2239,10 @@ static void srpt_drain_channel(struct ib_cm_id *cm_id)
 		if (ret < 0)
 			PRINT_ERROR("Setting queue pair in error state"
 			       " failed: %d", ret);
-	} else
-		TRACE_DBG("Channel already in state %s",
-			  get_ch_state_name(ch->state));
+		if (ch->last_wqe_received)
+			srpt_test_and_set_ch_state(ch, CH_DRAINING,
+						   CH_RELEASING);
+	}
 }
 
 static void srpt_free_ch(struct scst_session *sess)

srpt/src/ib_srpt.h

@@ -334,6 +334,7 @@ struct srpt_rdma_ch {
 	wait_queue_head_t	state_wq;
 	struct list_head	list;
 	struct list_head	cmd_wait_list;
+	bool			last_wqe_received;
 
 	struct scst_session	*scst_sess;
 	u8			sess_name[36];