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>

3 files changed, 21 insertions, 13 deletions

diff --git a/drivers/infiniband/hw/cxgb3/iwch_cm.c b/drivers/infiniband/hw/cxgb3/iwch_cm.c
index 3216bcad7e82..ad998c0b51e2 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;
 }
 
diff --git a/drivers/infiniband/hw/cxgb3/iwch_provider.h b/drivers/infiniband/hw/cxgb3/iwch_provider.h
index c5406da3f4cd..9a342c9b220d 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_provider.h
+++ b/drivers/infiniband/hw/cxgb3/iwch_provider.h
@@ -332,7 +332,7 @@ int iwch_bind_mw(struct ib_qp *qp,
                              struct ib_mw_bind *mw_bind);
 int iwch_poll_cq(struct ib_cq *ibcq, int num_entries, struct ib_wc *wc);
 int iwch_post_terminate(struct iwch_qp *qhp, struct respQ_msg_t *rsp_msg);
-int iwch_post_zb_read(struct iwch_qp *qhp);
+int iwch_post_zb_read(struct iwch_ep *ep);
 int iwch_register_device(struct iwch_dev *dev);
 void iwch_unregister_device(struct iwch_dev *dev);
 void stop_read_rep_timer(struct iwch_qp *qhp);
diff --git a/drivers/infiniband/hw/cxgb3/iwch_qp.c b/drivers/infiniband/hw/cxgb3/iwch_qp.c
index 1b4cd09f74dc..ecd313f359a4 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_qp.c
+++ b/drivers/infiniband/hw/cxgb3/iwch_qp.c
@@ -738,7 +738,7 @@ static inline void build_term_codes(struct respQ_msg_t *rsp_msg,
         }
 }
 
-int iwch_post_zb_read(struct iwch_qp *qhp)
+int iwch_post_zb_read(struct iwch_ep *ep)
 {
         union t3_wr *wqe;
         struct sk_buff *skb;
@@ -761,10 +761,10 @@ int iwch_post_zb_read(struct iwch_qp *qhp)
         wqe->read.local_len = cpu_to_be32(0);
         wqe->read.local_to = cpu_to_be64(1);
         wqe->send.wrh.op_seop_flags = cpu_to_be32(V_FW_RIWR_OP(T3_WR_READ));
-        wqe->send.wrh.gen_tid_len = cpu_to_be32(V_FW_RIWR_TID(qhp->ep->hwtid)|
+        wqe->send.wrh.gen_tid_len = cpu_to_be32(V_FW_RIWR_TID(ep->hwtid)|
                                                 V_FW_RIWR_LEN(flit_cnt));
         skb->priority = CPL_PRIORITY_DATA;
-        return iwch_cxgb3_ofld_send(qhp->rhp->rdev.t3cdev_p, skb);
+        return iwch_cxgb3_ofld_send(ep->com.qp->rhp->rdev.t3cdev_p, skb);
 }
 
 /*