From d8855c154e748c9ccd7c78e6478560ed61438e7d Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Tue, 1 Oct 2013 16:53:10 -0700 Subject: target: Fix recursive COMPARE_AND_WRITE callback failure This patch addresses a bug when compare_and_write_callback() invoked from target_complete_ok_work() hits an failure from __target_execute_cmd() -> cmd->execute_cmd(), that ends up calling transport_generic_request_failure() -> compare_and_write_post(), thus causing SCF_COMPARE_AND_WRITE_POST to incorrectly be set. The result of this bug is that target_complete_ok_work() no longer hits the if (!rc && !(cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE_POST) check that forces an immediate return, and instead double completes the se_cmd in question, triggering an OOPs in the process. This patch changes compare_and_write_post() to only set this bit when a failure has not already occured to ensure the immediate return from within target_complete_ok_work(), and thus allow transport_generic_request_failure() to handle the sending of the CHECK_CONDITION exception status. Reported-by: Thomas Glanzmann Tested-by: Thomas Glanzmann Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_sbc.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c index a9dca11..1393d0e 100644 --- a/drivers/target/target_core_sbc.c +++ b/drivers/target/target_core_sbc.c @@ -349,7 +349,16 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd) { struct se_device *dev = cmd->se_dev; - cmd->se_cmd_flags |= SCF_COMPARE_AND_WRITE_POST; + /* + * Only set SCF_COMPARE_AND_WRITE_POST to force a response fall-through + * within target_complete_ok_work() if the command was successfully + * sent to the backend driver. + */ + spin_lock_irq(&cmd->t_state_lock); + if ((cmd->transport_state & CMD_T_SENT) && !cmd->scsi_status) + cmd->se_cmd_flags |= SCF_COMPARE_AND_WRITE_POST; + spin_unlock_irq(&cmd->t_state_lock); + /* * Unlock ->caw_sem originally obtained during sbc_compare_and_write() * before the original READ I/O submission. -- cgit v1.1