3.16.39-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Nicholas Bellinger <[email protected]> commit 064cdd2d91c2805d788876082f31cc63506f22c3 upstream. This patch fixes a race in iscsit_release_commands_from_conn() -> iscsit_free_cmd() -> transport_generic_free_cmd() + wait_for_tasks=1, where CMD_T_FABRIC_STOP could end up being set after the final kref_put() is called from core_tmr_abort_task() context. This results in transport_generic_free_cmd() blocking indefinately on se_cmd->cmd_wait_comp, because the target_release_cmd_kref() check for CMD_T_FABRIC_STOP returns false. To address this bug, make iscsit_release_commands_from_conn() do list_splice and set CMD_T_FABRIC_STOP early while holding iscsi_conn->cmd_lock. Also make iscsit_aborted_task() only remove iscsi_cmd_t if CMD_T_FABRIC_STOP has not already been set. Finally in target_release_cmd_kref(), only honor fabric_stop if CMD_T_ABORTED has been set. Cc: Mike Christie <[email protected]> Cc: Quinn Tran <[email protected]> Cc: Himanshu Madhani <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Hannes Reinecke <[email protected]> Tested-by: Nicholas Bellinger <[email protected]> Signed-off-by: Nicholas Bellinger <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> --- drivers/target/iscsi/iscsi_target.c | 22 ++++++++++++++++------ drivers/target/target_core_transport.c | 3 ++- 2 files changed, 18 insertions(+), 7 deletions(-) --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -505,7 +505,8 @@ static void iscsit_aborted_task(struct i bool scsi_cmd = (cmd->iscsi_opcode == ISCSI_OP_SCSI_CMD); spin_lock_bh(&conn->cmd_lock); - if (!list_empty(&cmd->i_conn_node)) + if (!list_empty(&cmd->i_conn_node) && + !(cmd->se_cmd.transport_state & CMD_T_FABRIC_STOP)) list_del_init(&cmd->i_conn_node); spin_unlock_bh(&conn->cmd_lock); @@ -4174,6 +4175,7 @@ transport_err: static void iscsit_release_commands_from_conn(struct iscsi_conn *conn) { + LIST_HEAD(tmp_list); struct iscsi_cmd *cmd = NULL, *cmd_tmp = NULL; struct iscsi_session *sess = conn->sess; /* @@ -4182,18 +4184,26 @@ static void iscsit_release_commands_from * has been reset -> returned sleeping pre-handler state. */ spin_lock_bh(&conn->cmd_lock); - list_for_each_entry_safe(cmd, cmd_tmp, &conn->conn_cmd_list, i_conn_node) { + list_splice_init(&conn->conn_cmd_list, &tmp_list); + list_for_each_entry(cmd, &tmp_list, i_conn_node) { + struct se_cmd *se_cmd = &cmd->se_cmd; + + if (se_cmd->se_tfo != NULL) { + spin_lock(&se_cmd->t_state_lock); + se_cmd->transport_state |= CMD_T_FABRIC_STOP; + spin_unlock(&se_cmd->t_state_lock); + } + } + spin_unlock_bh(&conn->cmd_lock); + + list_for_each_entry_safe(cmd, cmd_tmp, &tmp_list, i_conn_node) { list_del_init(&cmd->i_conn_node); - spin_unlock_bh(&conn->cmd_lock); iscsit_increment_maxcmdsn(cmd, sess); - iscsit_free_cmd(cmd, true); - spin_lock_bh(&conn->cmd_lock); } - spin_unlock_bh(&conn->cmd_lock); } static void iscsit_stop_timers_for_cmds( --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -2457,7 +2457,8 @@ static void target_release_cmd_kref(stru spin_lock(&se_cmd->t_state_lock); - fabric_stop = (se_cmd->transport_state & CMD_T_FABRIC_STOP); + fabric_stop = (se_cmd->transport_state & CMD_T_FABRIC_STOP) && + (se_cmd->transport_state & CMD_T_ABORTED); spin_unlock(&se_cmd->t_state_lock); if (se_cmd->cmd_wait_set || fabric_stop) {
