From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> This patch has been added to the 3.12 stable tree. If you have any objections, please let us know. =============== commit 9b2792c3da1e80f2d460167d319302a24c9ca2b7 upstream. This patch addresses a long standing bug where the commit phase of COMPARE_AND_WRITE would result in a se_cmd->cmd_kref reference leak if se_cmd->scsi_status returned non SAM_STAT_GOOD. This would manifest first as a lost SCSI response, and eventual hung task during fabric driver logout or re-login, as existing shutdown logic waited for the COMPARE_AND_WRITE se_cmd->cmd_kref to reach zero. To address this bug, compare_and_write_post() has been changed to drop the incorrect !cmd->scsi_status conditional that was preventing *post_ret = 1 for being set during non SAM_STAT_GOOD status. This patch has been tested with SAM_STAT_CHECK_CONDITION status from normal target_complete_cmd() callback path, as well as the incoming __target_execute_cmd() submission failure path when se_cmd->execute_cmd() returns non zero status. Reported-by: Donald White <dew@xxxxxxxxx> Cc: Donald White <dew@xxxxxxxxx> Tested-by: Gary Guo <ghg@xxxxxxxxx> Cc: Gary Guo <ghg@xxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- drivers/target/target_core_sbc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c index 401fc7097935..552ac2d6fdc4 100644 --- a/drivers/target/target_core_sbc.c +++ b/drivers/target/target_core_sbc.c @@ -367,6 +367,7 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success, int *post_ret) { struct se_device *dev = cmd->se_dev; + sense_reason_t ret = TCM_NO_SENSE; /* * Only set SCF_COMPARE_AND_WRITE_POST to force a response fall-through @@ -374,9 +375,12 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success, * sent to the backend driver. */ spin_lock_irq(&cmd->t_state_lock); - if ((cmd->transport_state & CMD_T_SENT) && !cmd->scsi_status) { + if (cmd->transport_state & CMD_T_SENT) { cmd->se_cmd_flags |= SCF_COMPARE_AND_WRITE_POST; *post_ret = 1; + + if (cmd->scsi_status == SAM_STAT_CHECK_CONDITION) + ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; } spin_unlock_irq(&cmd->t_state_lock); @@ -386,7 +390,7 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success, */ up(&dev->caw_sem); - return TCM_NO_SENSE; + return ret; } static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool success, -- 2.11.1