RDMA/cxgb3: Don't post zero-byte read if endpoint is going away

tx_ack() wasn't checking the endpoint state and consequently would
attempt to post the p2p 0B read on an endpoint/QP that is closing or
aborting.  This causes a NULL pointer dereference crash.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 17 insertions, 9 deletions

diff --git a/drivers/infiniband/hw/cxgb3/iwch_cm.c b/drivers/infiniband/hw/cxgb3/iwch_cm.c
index 3216bcad7e8..ad998c0b51e 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_cm.c
+++ b/drivers/infiniband/hw/cxgb3/iwch_cm.c
@@ -913,7 +913,7 @@ static void process_mpa_reply(struct iwch_ep *ep, struct sk_buff *skb)
 		goto err;
 
 	if (peer2peer && iwch_rqes_posted(ep->com.qp) == 0) {
-		iwch_post_zb_read(ep->com.qp);
+		iwch_post_zb_read(ep);
 	}
 
 	goto out;
@@ -1077,6 +1077,8 @@ static int tx_ack(struct t3cdev *tdev, struct sk_buff *skb, void *ctx)
 	struct iwch_ep *ep = ctx;
 	struct cpl_wr_ack *hdr = cplhdr(skb);
 	unsigned int credits = ntohs(hdr->credits);
+	unsigned long flags;
+	int post_zb = 0;
 
 	PDBG("%s ep %p credits %u\n", __func__, ep, credits);
 
@@ -1086,28 +1088,34 @@ static int tx_ack(struct t3cdev *tdev, struct sk_buff *skb, void *ctx)
 		return CPL_RET_BUF_DONE;
 	}
 
+	spin_lock_irqsave(&ep->com.lock, flags);
 	BUG_ON(credits != 1);
 	dst_confirm(ep->dst);
 	if (!ep->mpa_skb) {
 		PDBG("%s rdma_init wr_ack ep %p state %u\n",
-			__func__, ep, state_read(&ep->com));
+			__func__, ep, ep->com.state);
 		if (ep->mpa_attr.initiator) {
 			PDBG("%s initiator ep %p state %u\n",
-				__func__, ep, state_read(&ep->com));
-			if (peer2peer)
-				iwch_post_zb_read(ep->com.qp);
+				__func__, ep, ep->com.state);
+			if (peer2peer && ep->com.state == FPDU_MODE)
+				post_zb = 1;
 		} else {
 			PDBG("%s responder ep %p state %u\n",
-				__func__, ep, state_read(&ep->com));
-			ep->com.rpl_done = 1;
-			wake_up(&ep->com.waitq);
+				__func__, ep, ep->com.state);
+			if (ep->com.state == MPA_REQ_RCVD) {
+				ep->com.rpl_done = 1;
+				wake_up(&ep->com.waitq);
+			}
 		}
 	} else {
 		PDBG("%s lsm ack ep %p state %u freeing skb\n",
-			__func__, ep, state_read(&ep->com));
+			__func__, ep, ep->com.state);
 		kfree_skb(ep->mpa_skb);
 		ep->mpa_skb = NULL;
 	}
+	spin_unlock_irqrestore(&ep->com.lock, flags);
+	if (post_zb)
+		iwch_post_zb_read(ep);
 	return CPL_RET_BUF_DONE;
 }