From 5e0cf5e6c43b9e19fc0284f69e5cd2b4a47523b0 Mon Sep 17 00:00:00 2001 From: Jiang Yi Date: Tue, 16 May 2017 17:57:55 +0800 Subject: [PATCH] iscsi-target: Always wait for kthread_should_stop() before kthread exit There are three timing problems in the kthread usages of iscsi_target_mod: - np_thread of struct iscsi_np - rx_thread and tx_thread of struct iscsi_conn In iscsit_close_connection(), it calls send_sig(SIGINT, conn->tx_thread, 1); kthread_stop(conn->tx_thread); In conn->tx_thread, which is iscsi_target_tx_thread(), when it receive SIGINT the kthread will exit without checking the return value of kthread_should_stop(). So if iscsi_target_tx_thread() exit right between send_sig(SIGINT...) and kthread_stop(...), the kthread_stop() will try to stop an already stopped kthread. This is invalid according to the documentation of kthread_stop(). (Fix -ECONNRESET logout handling in iscsi_target_tx_thread and early iscsi_target_rx_thread failure case - nab) Signed-off-by: Jiang Yi Cc: # v3.12+ Signed-off-by: Nicholas Bellinger --- drivers/target/iscsi/iscsi_target.c | 30 ++++++++++++++++++----- drivers/target/iscsi/iscsi_target_erl0.c | 6 ++++- drivers/target/iscsi/iscsi_target_erl0.h | 2 +- drivers/target/iscsi/iscsi_target_login.c | 4 +++ 4 files changed, 34 insertions(+), 8 deletions(-) diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index 26a9bcd5ee6a..0d8f81591bed 100644 --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -3790,6 +3790,8 @@ int iscsi_target_tx_thread(void *arg) { int ret = 0; struct iscsi_conn *conn = arg; + bool conn_freed = false; + /* * Allow ourselves to be interrupted by SIGINT so that a * connection recovery / failure event can be triggered externally. @@ -3815,12 +3817,14 @@ get_immediate: goto transport_err; ret = iscsit_handle_response_queue(conn); - if (ret == 1) + if (ret == 1) { goto get_immediate; - else if (ret == -ECONNRESET) + } else if (ret == -ECONNRESET) { + conn_freed = true; goto out; - else if (ret < 0) + } else if (ret < 0) { goto transport_err; + } } transport_err: @@ -3830,8 +3834,13 @@ transport_err: * responsible for cleaning up the early connection failure. */ if (conn->conn_state != TARG_CONN_STATE_IN_LOGIN) - iscsit_take_action_for_connection_exit(conn); + iscsit_take_action_for_connection_exit(conn, &conn_freed); out: + if (!conn_freed) { + while (!kthread_should_stop()) { + msleep(100); + } + } return 0; } @@ -4004,6 +4013,7 @@ int iscsi_target_rx_thread(void *arg) { int rc; struct iscsi_conn *conn = arg; + bool conn_freed = false; /* * Allow ourselves to be interrupted by SIGINT so that a @@ -4016,7 +4026,7 @@ int iscsi_target_rx_thread(void *arg) */ rc = wait_for_completion_interruptible(&conn->rx_login_comp); if (rc < 0 || iscsi_target_check_conn_state(conn)) - return 0; + goto out; if (!conn->conn_transport->iscsit_get_rx_pdu) return 0; @@ -4025,7 +4035,15 @@ int iscsi_target_rx_thread(void *arg) if (!signal_pending(current)) atomic_set(&conn->transport_failed, 1); - iscsit_take_action_for_connection_exit(conn); + iscsit_take_action_for_connection_exit(conn, &conn_freed); + +out: + if (!conn_freed) { + while (!kthread_should_stop()) { + msleep(100); + } + } + return 0; } diff --git a/drivers/target/iscsi/iscsi_target_erl0.c b/drivers/target/iscsi/iscsi_target_erl0.c index 9a96e17bf7cd..7fe2aa73cff6 100644 --- a/drivers/target/iscsi/iscsi_target_erl0.c +++ b/drivers/target/iscsi/iscsi_target_erl0.c @@ -930,8 +930,10 @@ static void iscsit_handle_connection_cleanup(struct iscsi_conn *conn) } } -void iscsit_take_action_for_connection_exit(struct iscsi_conn *conn) +void iscsit_take_action_for_connection_exit(struct iscsi_conn *conn, bool *conn_freed) { + *conn_freed = false; + spin_lock_bh(&conn->state_lock); if (atomic_read(&conn->connection_exit)) { spin_unlock_bh(&conn->state_lock); @@ -942,6 +944,7 @@ void iscsit_take_action_for_connection_exit(struct iscsi_conn *conn) if (conn->conn_state == TARG_CONN_STATE_IN_LOGOUT) { spin_unlock_bh(&conn->state_lock); iscsit_close_connection(conn); + *conn_freed = true; return; } @@ -955,4 +958,5 @@ void iscsit_take_action_for_connection_exit(struct iscsi_conn *conn) spin_unlock_bh(&conn->state_lock); iscsit_handle_connection_cleanup(conn); + *conn_freed = true; } diff --git a/drivers/target/iscsi/iscsi_target_erl0.h b/drivers/target/iscsi/iscsi_target_erl0.h index 60e69e2af6ed..3822d9cd1230 100644 --- a/drivers/target/iscsi/iscsi_target_erl0.h +++ b/drivers/target/iscsi/iscsi_target_erl0.h @@ -15,6 +15,6 @@ extern int iscsit_stop_time2retain_timer(struct iscsi_session *); extern void iscsit_connection_reinstatement_rcfr(struct iscsi_conn *); extern void iscsit_cause_connection_reinstatement(struct iscsi_conn *, int); extern void iscsit_fall_back_to_erl0(struct iscsi_session *); -extern void iscsit_take_action_for_connection_exit(struct iscsi_conn *); +extern void iscsit_take_action_for_connection_exit(struct iscsi_conn *, bool *); #endif /*** ISCSI_TARGET_ERL0_H ***/ diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c index 66238477137b..92b96b51d506 100644 --- a/drivers/target/iscsi/iscsi_target_login.c +++ b/drivers/target/iscsi/iscsi_target_login.c @@ -1464,5 +1464,9 @@ int iscsi_target_login_thread(void *arg) break; } + while (!kthread_should_stop()) { + msleep(100); + } + return 0; } -- 2.30.2