[PATCH 3.14 88/98] iser-target: Fix connected_handler + teardown flow race

Greg Kroah-Hartman
2015-01-25T19:06:22Z

From: Sagi Grimberg <sagig@mellanox.com>

commit 19e2090fb246ca21b3e569ead51a6a7a1748eadd upstream.

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>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/infiniband/ulp/isert/ib_isert.c | 31 +++++++++++++++++++------------
1 file changed, 19 insertions(+), 12 deletions(-)

--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -136,12 +136,18 @@ isert_conn_setup_qp(struct isert_conn *i
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
@@ -527,7 +533,6 @@ isert_connect_request(struct rdma_cm_id
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->responder_resources = event->param.conn.responder_resources;
isert_conn->initiator_depth = event->param.conn.initiator_depth;
@@ -649,18 +654,20 @@ isert_connect_release(struct 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);

@@ -683,7 +690,7 @@ isert_connect_release(struct 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);

@@ -761,16 +768,16 @@ isert_conn_terminate(struct 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);
@@ -785,7 +792,7 @@ isert_disconnected_handler(struct rdma_c
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);
}