From dff0ca9ea7dc8be2181a62df4a722c32ce68ff4a Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Tue, 17 May 2016 22:19:10 -0700 Subject: target: Fix ordered task target_setup_cmd_from_cdb exception hang If a command with a Simple task attribute is failed due to a Unit Attention, then a subsequent command with an Ordered task attribute will hang forever. The reason for this is that the Unit Attention status is checked for in target_setup_cmd_from_cdb, before the call to target_execute_cmd, which calls target_handle_task_attr, which in turn increments dev->simple_cmds. However, transport_generic_request_failure still calls transport_complete_task_attr, which will decrement dev->simple_cmds. In this case, simple_cmds is now -1. So when a command with the Ordered task attribute is sent, target_handle_task_attr sees that dev->simple_cmds is not 0, so it decides it can't execute the command until all the (nonexistent) Simple commands have completed. Reported-by: Michael Cyr Tested-by: Michael Cyr Reported-by: Bryant G. Ly Tested-by: Bryant G. Ly Cc: stable@vger.kernel.org # 4.4+ Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_transport.c | 62 +++++++++++++++++++--------------- 1 file changed, 35 insertions(+), 27 deletions(-) (limited to 'drivers/target/target_core_transport.c') diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index 38bf2dcf926a..a6e1edcfefbd 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -1303,23 +1303,6 @@ target_setup_cmd_from_cdb(struct se_cmd *cmd, unsigned char *cdb) trace_target_sequencer_start(cmd); - /* - * Check for an existing UNIT ATTENTION condition - */ - ret = target_scsi3_ua_check(cmd); - if (ret) - return ret; - - ret = target_alua_state_check(cmd); - if (ret) - return ret; - - ret = target_check_reservation(cmd); - if (ret) { - cmd->scsi_status = SAM_STAT_RESERVATION_CONFLICT; - return ret; - } - ret = dev->transport->parse_cdb(cmd); if (ret == TCM_UNSUPPORTED_SCSI_OPCODE) pr_warn_ratelimited("%s/%s: Unsupported SCSI Opcode 0x%02x, sending CHECK_CONDITION.\n", @@ -1761,20 +1744,45 @@ queue_full: } EXPORT_SYMBOL(transport_generic_request_failure); -void __target_execute_cmd(struct se_cmd *cmd) +void __target_execute_cmd(struct se_cmd *cmd, bool do_checks) { sense_reason_t ret; - if (cmd->execute_cmd) { - ret = cmd->execute_cmd(cmd); - if (ret) { - spin_lock_irq(&cmd->t_state_lock); - cmd->transport_state &= ~(CMD_T_BUSY|CMD_T_SENT); - spin_unlock_irq(&cmd->t_state_lock); + if (!cmd->execute_cmd) { + ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; + goto err; + } + if (do_checks) { + /* + * Check for an existing UNIT ATTENTION condition after + * target_handle_task_attr() has done SAM task attr + * checking, and possibly have already defered execution + * out to target_restart_delayed_cmds() context. + */ + ret = target_scsi3_ua_check(cmd); + if (ret) + goto err; + + ret = target_alua_state_check(cmd); + if (ret) + goto err; - transport_generic_request_failure(cmd, ret); + ret = target_check_reservation(cmd); + if (ret) { + cmd->scsi_status = SAM_STAT_RESERVATION_CONFLICT; + goto err; } } + + ret = cmd->execute_cmd(cmd); + if (!ret) + return; +err: + spin_lock_irq(&cmd->t_state_lock); + cmd->transport_state &= ~(CMD_T_BUSY|CMD_T_SENT); + spin_unlock_irq(&cmd->t_state_lock); + + transport_generic_request_failure(cmd, ret); } static int target_write_prot_action(struct se_cmd *cmd) @@ -1899,7 +1907,7 @@ void target_execute_cmd(struct se_cmd *cmd) return; } - __target_execute_cmd(cmd); + __target_execute_cmd(cmd, true); } EXPORT_SYMBOL(target_execute_cmd); @@ -1923,7 +1931,7 @@ static void target_restart_delayed_cmds(struct se_device *dev) list_del(&cmd->se_delayed_node); spin_unlock(&dev->delayed_cmd_lock); - __target_execute_cmd(cmd); + __target_execute_cmd(cmd, true); if (cmd->sam_task_attr == TCM_ORDERED_TAG) break; -- cgit v1.2.3