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Subject[ 04/99] iser-target: Fix session reset bug with RDMA_CM_EVENT_DISCONNECTED
Date
3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nicholas Bellinger <nab@linux-iscsi.org>

commit b2cb96494d83b894a43ba8b9023eead8ff50684b upstream.

This patch addresses a bug where RDMA_CM_EVENT_DISCONNECTED may occur
before the connection shutdown has been completed by rx/tx threads,
that causes isert_free_conn() to wait indefinately on ->conn_wait.

This patch allows isert_disconnect_work code to invoke rdma_disconnect
when isert_disconnect_work() process context is started by client
session reset before isert_free_conn() code has been reached.

It also adds isert_conn->conn_mutex protection for ->state within
isert_disconnect_work(), isert_cq_comp_err() and isert_free_conn()
code, along with isert_check_state() for wait_event usage.

(v2: Add explicit iscsit_cause_connection_reinstatement call
during isert_disconnect_work() to force conn reset)

Cc: Or Gerlitz <ogerlitz@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 | 70 ++++++++++++++++++++++++++-----
drivers/infiniband/ulp/isert/ib_isert.h | 1
drivers/target/iscsi/iscsi_target_erl0.c | 1
include/target/iscsi/iscsi_transport.h | 4 +
4 files changed, 66 insertions(+), 10 deletions(-)

--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -388,6 +388,7 @@ isert_connect_request(struct rdma_cm_id
init_waitqueue_head(&isert_conn->conn_wait_comp_err);
kref_init(&isert_conn->conn_kref);
kref_get(&isert_conn->conn_kref);
+ mutex_init(&isert_conn->conn_mutex);

cma_id->context = isert_conn;
isert_conn->conn_cm_id = cma_id;
@@ -540,15 +541,32 @@ isert_disconnect_work(struct work_struct
struct isert_conn, conn_logout_work);

pr_debug("isert_disconnect_work(): >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
-
+ mutex_lock(&isert_conn->conn_mutex);
isert_conn->state = ISER_CONN_DOWN;

if (isert_conn->post_recv_buf_count == 0 &&
atomic_read(&isert_conn->post_send_buf_count) == 0) {
pr_debug("Calling wake_up(&isert_conn->conn_wait);\n");
- wake_up(&isert_conn->conn_wait);
+ mutex_unlock(&isert_conn->conn_mutex);
+ goto wake_up;
+ }
+ if (!isert_conn->conn_cm_id) {
+ mutex_unlock(&isert_conn->conn_mutex);
+ isert_put_conn(isert_conn);
+ return;
+ }
+ if (!isert_conn->logout_posted) {
+ pr_debug("Calling rdma_disconnect for !logout_posted from"
+ " isert_disconnect_work\n");
+ rdma_disconnect(isert_conn->conn_cm_id);
+ mutex_unlock(&isert_conn->conn_mutex);
+ iscsit_cause_connection_reinstatement(isert_conn->conn, 0);
+ goto wake_up;
}
+ mutex_unlock(&isert_conn->conn_mutex);

+wake_up:
+ wake_up(&isert_conn->conn_wait);
isert_put_conn(isert_conn);
}

@@ -1423,7 +1441,11 @@ isert_cq_comp_err(struct iser_tx_desc *t
pr_debug("isert_cq_comp_err >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
pr_debug("Calling wake_up from isert_cq_comp_err\n");

- isert_conn->state = ISER_CONN_TERMINATING;
+ mutex_lock(&isert_conn->conn_mutex);
+ if (isert_conn->state != ISER_CONN_DOWN)
+ isert_conn->state = ISER_CONN_TERMINATING;
+ mutex_unlock(&isert_conn->conn_mutex);
+
wake_up(&isert_conn->conn_wait_comp_err);
}
}
@@ -2193,6 +2215,17 @@ isert_free_np(struct iscsi_np *np)
kfree(isert_np);
}

+static int isert_check_state(struct isert_conn *isert_conn, int state)
+{
+ int ret;
+
+ mutex_lock(&isert_conn->conn_mutex);
+ ret = (isert_conn->state == state);
+ mutex_unlock(&isert_conn->conn_mutex);
+
+ return ret;
+}
+
static void isert_free_conn(struct iscsi_conn *conn)
{
struct isert_conn *isert_conn = conn->context;
@@ -2202,26 +2235,43 @@ static void isert_free_conn(struct iscsi
* Decrement post_send_buf_count for special case when called
* from isert_do_control_comp() -> iscsit_logout_post_handler()
*/
+ mutex_lock(&isert_conn->conn_mutex);
if (isert_conn->logout_posted)
atomic_dec(&isert_conn->post_send_buf_count);

- if (isert_conn->conn_cm_id)
+ if (isert_conn->conn_cm_id && isert_conn->state != ISER_CONN_DOWN) {
+ pr_debug("Calling rdma_disconnect from isert_free_conn\n");
rdma_disconnect(isert_conn->conn_cm_id);
+ }
/*
* Only wait for conn_wait_comp_err if the isert_conn made it
* into full feature phase..
*/
- if (isert_conn->state > ISER_CONN_INIT) {
+ if (isert_conn->state == ISER_CONN_UP) {
pr_debug("isert_free_conn: Before wait_event comp_err %d\n",
isert_conn->state);
+ mutex_unlock(&isert_conn->conn_mutex);
+
wait_event(isert_conn->conn_wait_comp_err,
- isert_conn->state == ISER_CONN_TERMINATING);
- pr_debug("isert_free_conn: After wait_event #1 >>>>>>>>>>>>\n");
+ (isert_check_state(isert_conn, ISER_CONN_TERMINATING)));
+
+ wait_event(isert_conn->conn_wait,
+ (isert_check_state(isert_conn, ISER_CONN_DOWN)));
+
+ isert_put_conn(isert_conn);
+ return;
+ }
+ if (isert_conn->state == ISER_CONN_INIT) {
+ mutex_unlock(&isert_conn->conn_mutex);
+ isert_put_conn(isert_conn);
+ return;
}
+ pr_debug("isert_free_conn: wait_event conn_wait %d\n",
+ isert_conn->state);
+ mutex_unlock(&isert_conn->conn_mutex);

- pr_debug("isert_free_conn: wait_event conn_wait %d\n", isert_conn->state);
- wait_event(isert_conn->conn_wait, isert_conn->state == ISER_CONN_DOWN);
- pr_debug("isert_free_conn: After wait_event #2 >>>>>>>>>>>>>>>>>>>>\n");
+ wait_event(isert_conn->conn_wait,
+ (isert_check_state(isert_conn, ISER_CONN_DOWN)));

isert_put_conn(isert_conn);
}
--- a/drivers/infiniband/ulp/isert/ib_isert.h
+++ b/drivers/infiniband/ulp/isert/ib_isert.h
@@ -102,6 +102,7 @@ struct isert_conn {
struct ib_qp *conn_qp;
struct isert_device *conn_device;
struct work_struct conn_logout_work;
+ struct mutex conn_mutex;
wait_queue_head_t conn_wait;
wait_queue_head_t conn_wait_comp_err;
struct kref conn_kref;
--- a/drivers/target/iscsi/iscsi_target_erl0.c
+++ b/drivers/target/iscsi/iscsi_target_erl0.c
@@ -909,6 +909,7 @@ void iscsit_cause_connection_reinstateme
wait_for_completion(&conn->conn_wait_comp);
complete(&conn->conn_post_wait_comp);
}
+EXPORT_SYMBOL(iscsit_cause_connection_reinstatement);

void iscsit_fall_back_to_erl0(struct iscsi_session *sess)
{
--- a/include/target/iscsi/iscsi_transport.h
+++ b/include/target/iscsi/iscsi_transport.h
@@ -67,6 +67,10 @@ extern int iscsit_logout_post_handler(st
*/
extern void iscsit_increment_maxcmdsn(struct iscsi_cmd *, struct iscsi_session *);
/*
+ * From iscsi_target_erl0.c
+ */
+extern void iscsit_cause_connection_reinstatement(struct iscsi_conn *, int);
+/*
* From iscsi_target_erl1.c
*/
extern void iscsit_stop_dataout_timer(struct iscsi_cmd *);



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