iscsi-target: Set session_fall_back_to_erl0 when forcing reinstatement

commit 197b806ae5db60c6f609d74da04ddb62ea5e1b00 upstream.

While testing modification of per se_node_acl queue_depth forcing
session reinstatement via lio_target_nacl_cmdsn_depth_store() ->
core_tpg_set_initiator_node_queue_depth(), a hung task bug triggered
when changing cmdsn_depth invoked session reinstatement while an iscsi
login was already waiting for session reinstatement to complete.

This can happen when an outstanding se_cmd descriptor is taking a
long time to complete, and session reinstatement from iscsi login
or cmdsn_depth change occurs concurrently.

To address this bug, explicitly set session_fall_back_to_erl0 = 1
when forcing session reinstatement, so session reinstatement is
not attempted if an active session is already being shutdown.

This patch has been tested with two scenarios.  The first when
iscsi login is blocked waiting for iscsi session reinstatement
to complete followed by queue_depth change via configfs, and
second when queue_depth change via configfs us blocked followed
by a iscsi login driven session reinstatement.

Note this patch depends on commit d36ad77f702 to handle multiple
sessions per se_node_acl when changing cmdsn_depth, and for
pre v4.5 kernels will need to be included for stable as well.

Reported-by: Gary Guo <ghg@datera.io>
Tested-by: Gary Guo <ghg@datera.io>
Cc: Gary Guo <ghg@datera.io>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index da2c73a255dec194bba90826f6b3e95e9a264e32..4d970a7bbd971e39d5ea88c1c99bf19cf670f003 100644 (file)
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -4673,6 +4673,7 @@ int iscsit_release_sessions_for_tpg(struct iscsi_portal_group *tpg, int force)
                        continue;
                }
                atomic_set(&sess->session_reinstatement, 1);
+               atomic_set(&sess->session_fall_back_to_erl0, 1);
                spin_unlock(&sess->conn_lock);
 
                list_move_tail(&se_sess->sess_list, &free_list);

diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c
index bf40f03755ddc50697652ccde864d40df840fa0b..11291c1c779ada4273bfff3872338c1d02285845 100644 (file)
--- a/drivers/target/iscsi/iscsi_target_configfs.c
+++ b/drivers/target/iscsi/iscsi_target_configfs.c
@@ -1531,6 +1531,7 @@ static void lio_tpg_close_session(struct se_session *se_sess)
                return;
        }
        atomic_set(&sess->session_reinstatement, 1);
+       atomic_set(&sess->session_fall_back_to_erl0, 1);
        spin_unlock(&sess->conn_lock);
 
        iscsit_stop_time2retain_timer(sess);

diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index 450f51deb2a2ae18137ede36d4a3e8c188fd7352..d11c9891134d78b579705f97bd4a25a242ee8564 100644 (file)
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -206,6 +206,7 @@ int iscsi_check_for_session_reinstatement(struct iscsi_conn *conn)
                            initiatorname_param->value) &&
                   (sess_p->sess_ops->SessionType == sessiontype))) {
                        atomic_set(&sess_p->session_reinstatement, 1);
+                       atomic_set(&sess_p->session_fall_back_to_erl0, 1);
                        spin_unlock(&sess_p->conn_lock);
                        iscsit_inc_session_usage_count(sess_p);
                        iscsit_stop_time2retain_timer(sess_p);