4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Jiang Yi <jiangyil...@gmail.com> commit 5e0cf5e6c43b9e19fc0284f69e5cd2b4a47523b0 upstream. 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 <jiangyil...@gmail.com> Signed-off-by: Nicholas Bellinger <n...@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- 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(-) --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -3798,6 +3798,8 @@ 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. @@ -3823,12 +3825,14 @@ 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: @@ -3838,8 +3842,13 @@ 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; } @@ -4012,6 +4021,7 @@ 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 @@ -4024,7 +4034,7 @@ 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; @@ -4033,7 +4043,15 @@ 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; } --- 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_cle } } -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_e 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_e spin_unlock_bh(&conn->state_lock); iscsit_handle_connection_cleanup(conn); + *conn_freed = true; } --- a/drivers/target/iscsi/iscsi_target_erl0.h +++ b/drivers/target/iscsi/iscsi_target_erl0.h @@ -9,6 +9,6 @@ extern int iscsit_stop_time2retain_timer 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 ***/ --- a/drivers/target/iscsi/iscsi_target_login.c +++ b/drivers/target/iscsi/iscsi_target_login.c @@ -1460,5 +1460,9 @@ int iscsi_target_login_thread(void *arg) break; } + while (!kthread_should_stop()) { + msleep(100); + } + return 0; }