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 b7d747e92c7abf589e35154b25482a9dedb57118..40e50f2d209d360adca19df23009604e6dccb224 100644 (file)
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -4671,6 +4671,7 @@ 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 e980e2d0c2db5512ac29b9974310b93ff910c89b..7e70fe849f0da4c77d151f0e25553163af260ee1 100644 (file)
--- a/drivers/target/iscsi/iscsi_target_configfs.c
+++ b/drivers/target/iscsi/iscsi_target_configfs.c
@@ -1530,6 +1530,7 @@ 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 15f79a2ca34ab6e17fd5fda6f68425b9af1809eb..96c55bc10ac9dd4049714b508e6023318a71490a 100644 (file)
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -204,6 +204,7 @@ 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);