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Subject[PATCH 3.12 149/181] Target/iser: Fix hangs in connection teardown
Date
From: Sagi Grimberg <sagig@mellanox.com>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit 9d49f5e284e700576f3b65f1e28dea8539da6661 upstream.

In ungraceful teardowns isert close flows seem racy such that
isert_wait_conn hangs as RDMA_CM_EVENT_DISCONNECTED never
gets invoked (no one called rdma_disconnect).

Both graceful and ungraceful teardowns will have rx flush errors
(isert posts a batch once connection is established). Once all
flush errors are consumed we invoke isert_wait_conn and it will
be responsible for calling rdma_disconnect. This way it can be
sure that rdma_disconnect was called and it won't wait forever.

This patch also removes the logout_posted indicator. either the
logout completion was consumed and no problem decrementing the
post_send_buf_count, or it was consumed as a flush error. no point
of keeping it for isert_wait_conn as there is no danger that
isert_conn will be accidentally removed while it is running.

(Drop unnecessary sleep_on_conn_wait_comp check in
isert_cq_rx_comp_err - nab)

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/infiniband/ulp/isert/ib_isert.c | 31 ++++++++++---------------------
drivers/infiniband/ulp/isert/ib_isert.h | 1 -
2 files changed, 10 insertions(+), 22 deletions(-)

diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index c09d2f0cae49..9d3dec3a5235 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -688,14 +688,10 @@ isert_disconnect_work(struct work_struct *work)
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;
- }
+
+ /* Send DREQ/DREP towards our initiator */
+ rdma_disconnect(isert_conn->conn_cm_id);
+
mutex_unlock(&isert_conn->conn_mutex);

wake_up:
@@ -1581,11 +1577,8 @@ isert_do_control_comp(struct work_struct *work)
break;
case ISTATE_SEND_LOGOUTRSP:
pr_debug("Calling iscsit_logout_post_handler >>>>>>>>>>>>>>\n");
- /*
- * Call atomic_dec(&isert_conn->post_send_buf_count)
- * from isert_wait_conn()
- */
- isert_conn->logout_posted = true;
+
+ atomic_dec(&isert_conn->post_send_buf_count);
iscsit_logout_post_handler(cmd, cmd->conn);
break;
case ISTATE_SEND_TEXTRSP:
@@ -1699,6 +1692,8 @@ isert_cq_rx_comp_err(struct isert_conn *isert_conn)
isert_conn->state = ISER_CONN_DOWN;
mutex_unlock(&isert_conn->conn_mutex);

+ iscsit_cause_connection_reinstatement(isert_conn->conn, 0);
+
complete(&isert_conn->conn_wait_comp_err);
}

@@ -2690,15 +2685,9 @@ static void isert_wait_conn(struct iscsi_conn *conn)
struct isert_conn *isert_conn = conn->context;

pr_debug("isert_wait_conn: Starting \n");
- /*
- * 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 && isert_conn->state != ISER_CONN_DOWN) {
+ mutex_lock(&isert_conn->conn_mutex);
+ if (isert_conn->conn_cm_id) {
pr_debug("Calling rdma_disconnect from isert_wait_conn\n");
rdma_disconnect(isert_conn->conn_cm_id);
}
diff --git a/drivers/infiniband/ulp/isert/ib_isert.h b/drivers/infiniband/ulp/isert/ib_isert.h
index ba695c33a2df..f0ed44c89b71 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.h
+++ b/drivers/infiniband/ulp/isert/ib_isert.h
@@ -90,7 +90,6 @@ struct isert_device;

struct isert_conn {
enum iser_conn_state state;
- bool logout_posted;
int post_recv_buf_count;
atomic_t post_send_buf_count;
u32 responder_resources;
--
2.0.0


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