xprtrdma: Protect ia->ri_id when unmapping/invalidating MRs

Ensure ia->ri_id remains valid while invoking dma_unmap_page() or
posting LOCAL_INV during a transport reconnect. Otherwise,
ia->ri_id->device or ia->ri_id->qp is NULL, which triggers a panic.

BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=259
Fixes: ec62f40 'xprtrdma: Ensure ia->ri_id->qp is not NULL when reconnecting'
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Tested-by: Shirley Ma <shirley.ma@oracle.com>
Tested-by: Devesh Sharma <devesh.sharma@emulex.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

2 files changed, 18 insertions, 6 deletions

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index f337bdaa9939..aa08de89de42 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -613,6 +613,7 @@ rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr, int memreg)
         /* Else will do memory reg/dereg for each chunk */
         ia->ri_memreg_strategy = memreg;
 
+        rwlock_init(&ia->ri_qplock);
         return 0;
 out2:
         rdma_destroy_id(ia->ri_id);
@@ -859,7 +860,7 @@ rpcrdma_ep_destroy(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
 int
 rpcrdma_ep_connect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
 {
-        struct rdma_cm_id *id;
+        struct rdma_cm_id *id, *old;
         int rc = 0;
         int retry_count = 0;
 
@@ -905,9 +906,14 @@ retry:
                         rc = -ENETUNREACH;
                         goto out;
                 }
-                rdma_destroy_qp(ia->ri_id);
-                rdma_destroy_id(ia->ri_id);
+
+                write_lock(&ia->ri_qplock);
+                old = ia->ri_id;
                 ia->ri_id = id;
+                write_unlock(&ia->ri_qplock);
+
+                rdma_destroy_qp(old);
+                rdma_destroy_id(old);
         } else {
                 dprintk("RPC:       %s: connecting...\n", __func__);
                 rc = rdma_create_qp(ia->ri_id, ia->ri_pd, &ep->rep_attr);
@@ -1590,9 +1596,6 @@ rpcrdma_deregister_frmr_external(struct rpcrdma_mr_seg *seg,
         struct ib_send_wr invalidate_wr, *bad_wr;
         int rc;
 
-        while (seg1->mr_nsegs--)
-                rpcrdma_unmap_one(ia, seg++);
-
         memset(&invalidate_wr, 0, sizeof invalidate_wr);
         invalidate_wr.wr_id = (unsigned long)(void *)seg1->mr_chunk.rl_mw;
         invalidate_wr.opcode = IB_WR_LOCAL_INV;
@@ -1600,7 +1603,11 @@ rpcrdma_deregister_frmr_external(struct rpcrdma_mr_seg *seg,
         invalidate_wr.ex.invalidate_rkey = seg1->mr_chunk.rl_mw->r.frmr.fr_mr->rkey;
         DECR_CQCOUNT(&r_xprt->rx_ep);
 
+        read_lock(&ia->ri_qplock);
+        while (seg1->mr_nsegs--)
+                rpcrdma_unmap_one(ia, seg++);
         rc = ib_post_send(ia->ri_id->qp, &invalidate_wr, &bad_wr);
+        read_unlock(&ia->ri_qplock);
         if (rc)
                 dprintk("RPC:       %s: failed ib_post_send for invalidate,"
                         " status %i\n", __func__, rc);
@@ -1661,8 +1668,10 @@ rpcrdma_deregister_fmr_external(struct rpcrdma_mr_seg *seg,
 
         list_add(&seg1->mr_chunk.rl_mw->r.fmr->list, &l);
         rc = ib_unmap_fmr(&l);
+        read_lock(&ia->ri_qplock);
         while (seg1->mr_nsegs--)
                 rpcrdma_unmap_one(ia, seg++);
+        read_unlock(&ia->ri_qplock);
         if (rc)
                 dprintk("RPC:       %s: failed ib_unmap_fmr,"
                         " status %i\n", __func__, rc);
@@ -1718,7 +1727,9 @@ rpcrdma_deregister_external(struct rpcrdma_mr_seg *seg,
 
 #if RPCRDMA_PERSISTENT_REGISTRATION
         case RPCRDMA_ALLPHYSICAL:
+                read_lock(&ia->ri_qplock);
                 rpcrdma_unmap_one(ia, seg);
+                read_unlock(&ia->ri_qplock);
                 break;
 #endif
 
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 89e7cd479705..97ca516ec619 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -59,6 +59,7 @@
  * Interface Adapter -- one per transport instance
  */
 struct rpcrdma_ia {
+        rwlock_t                ri_qplock;
         struct rdma_cm_id       *ri_id;
         struct ib_pd            *ri_pd;
         struct ib_mr            *ri_bind_mem;