iser-target: Fix connected_handler + teardown flow race

Take isert_conn pointer from cm_id->qp->qp_context. This
will allow us to know that the cm_id context is always
the network portal. This will make the cm_id event check
(connection or network portal) more reliable.

In order to avoid a NULL dereference in cma_id->qp->qp_context
we destroy the qp after we destroy the cm_id (and make the
dereference safe). session stablishment/teardown sequences
can happen in parallel, we should take into account that
connected_handler might race with connection teardown flow.

Also, protect isert_conn->conn_device->active_qps decrement
within the error patch during QP creation failure and the
normal teardown path in isert_connect_release().

Squashed:

iser-target: Decrement completion context active_qps in error flow

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 19 insertions, 12 deletions

diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index a0fd77bf8f88..054fa425d09e 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -141,12 +141,18 @@ isert_conn_setup_qp(struct isert_conn *isert_conn, struct rdma_cm_id *cma_id,
         ret = rdma_create_qp(cma_id, isert_conn->conn_pd, &attr);
         if (ret) {
                 pr_err("rdma_create_qp failed for cma_id %d\n", ret);
-                return ret;
+                goto err;
         }
         isert_conn->conn_qp = cma_id->qp;
         pr_debug("rdma_create_qp() returned success >>>>>>>>>>>>>>>>>>>>>>>>>.\n");
 
         return 0;
+err:
+        mutex_lock(&device_list_mutex);
+        device->cq_active_qps[min_index]--;
+        mutex_unlock(&device_list_mutex);
+
+        return ret;
 }
 
 static void
@@ -602,7 +608,6 @@ isert_connect_request(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
         spin_lock_init(&isert_conn->conn_lock);
         INIT_LIST_HEAD(&isert_conn->conn_fr_pool);
 
-        cma_id->context = isert_conn;
         isert_conn->conn_cm_id = cma_id;
 
         isert_conn->login_buf = kzalloc(ISCSI_DEF_MAX_RECV_SEG_LEN +
@@ -734,18 +739,20 @@ isert_connect_release(struct isert_conn *isert_conn)
         if (device && device->use_fastreg)
                 isert_conn_free_fastreg_pool(isert_conn);
 
+        isert_free_rx_descriptors(isert_conn);
+        rdma_destroy_id(isert_conn->conn_cm_id);
+
         if (isert_conn->conn_qp) {
                 cq_index = ((struct isert_cq_desc *)
                         isert_conn->conn_qp->recv_cq->cq_context)->cq_index;
                 pr_debug("isert_connect_release: cq_index: %d\n", cq_index);
+                mutex_lock(&device_list_mutex);
                 isert_conn->conn_device->cq_active_qps[cq_index]--;
+                mutex_unlock(&device_list_mutex);
 
-                rdma_destroy_qp(isert_conn->conn_cm_id);
+                ib_destroy_qp(isert_conn->conn_qp);
         }
 
-        isert_free_rx_descriptors(isert_conn);
-        rdma_destroy_id(isert_conn->conn_cm_id);
-
         ib_dereg_mr(isert_conn->conn_mr);
         ib_dealloc_pd(isert_conn->conn_pd);
 
@@ -768,7 +775,7 @@ isert_connect_release(struct isert_conn *isert_conn)
 static void
 isert_connected_handler(struct rdma_cm_id *cma_id)
 {
-        struct isert_conn *isert_conn = cma_id->context;
+        struct isert_conn *isert_conn = cma_id->qp->qp_context;
 
         pr_info("conn %p\n", isert_conn);
 
@@ -846,16 +853,16 @@ isert_conn_terminate(struct isert_conn *isert_conn)
 static int
 isert_disconnected_handler(struct rdma_cm_id *cma_id)
 {
+        struct iscsi_np *np = cma_id->context;
+        struct isert_np *isert_np = np->np_context;
         struct isert_conn *isert_conn;
 
-        if (!cma_id->qp) {
-                struct isert_np *isert_np = cma_id->context;
-
+        if (isert_np->np_cm_id == cma_id) {
                 isert_np->np_cm_id = NULL;
                 return -1;
         }
 
-        isert_conn = (struct isert_conn *)cma_id->context;
+        isert_conn = cma_id->qp->qp_context;
 
         mutex_lock(&isert_conn->conn_mutex);
         isert_conn_terminate(isert_conn);
@@ -870,7 +877,7 @@ isert_disconnected_handler(struct rdma_cm_id *cma_id)
 static void
 isert_connect_error(struct rdma_cm_id *cma_id)
 {
-        struct isert_conn *isert_conn = (struct isert_conn *)cma_id->context;
+        struct isert_conn *isert_conn = cma_id->qp->qp_context;
 
         isert_put_conn(isert_conn);
 }