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Commit 953bcf7a authored by Bart Van Assche's avatar Bart Van Assche Committed by Martin K. Petersen
Browse files

scsi: target: Document when CMD_T_STOP and CMD_T_COMPLETE are set 



Document those aspects of transport_cmd_check_stop_to_fabric() and
transport_generic_free_cmd() of which it is nontrivial to derive these from
their implementation.

Signed-off-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: default avatarMike Christie <mchristi@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 00d909a1

drivers/target/target_core_transport.c

+28 −6
Original line number Original line Diff line number Diff line
@@ -632,6 +632,13 @@ static void target_remove_from_state_list(struct se_cmd *cmd) 
	spin_unlock_irqrestore(&dev->execute_task_lock, flags);

	spin_unlock_irqrestore(&dev->execute_task_lock, flags);

}

}





/*

 * This function is called by the target core after the target core has

 * finished processing a SCSI command or SCSI TMF. Both the regular command

 * processing code and the code for aborting commands can call this

 * function. CMD_T_STOP is set if and only if another thread is waiting

 * inside transport_wait_for_tasks() for t_transport_stop_comp.

 */

static int transport_cmd_check_stop_to_fabric(struct se_cmd *cmd)

static int transport_cmd_check_stop_to_fabric(struct se_cmd *cmd)

{

{

	unsigned long flags;

	unsigned long flags;
@@ -2624,6 +2631,27 @@ static void target_wait_free_cmd(struct se_cmd *cmd, bool *aborted, bool *tas) 
	spin_unlock_irqrestore(&cmd->t_state_lock, flags);

	spin_unlock_irqrestore(&cmd->t_state_lock, flags);

}

}





/*

 * This function is called by frontend drivers after processing of a command

 * has finished.

 *

 * The protocol for ensuring that either the regular flow or the TMF

 * code drops one reference is as follows:

 * - Calling .queue_data_in(), .queue_status() or queue_tm_rsp() will cause

 *   the frontend driver to drop one reference, synchronously or asynchronously.

 * - During regular command processing the target core sets CMD_T_COMPLETE

 *   before invoking one of the .queue_*() functions.

 * - The code that aborts commands skips commands and TMFs for which

 *   CMD_T_COMPLETE has been set.

 * - CMD_T_ABORTED is set atomically after the CMD_T_COMPLETE check for

 *   commands that will be aborted.

 * - If the CMD_T_ABORTED flag is set but CMD_T_TAS has not been set

 *   transport_generic_free_cmd() skips its call to target_put_sess_cmd().

 * - For aborted commands for which CMD_T_TAS has been set .queue_status() will

 *   be called and will drop a reference.

 * - For aborted commands for which CMD_T_TAS has not been set .aborted_task()

 *   will be called. transport_cmd_finish_abort() will drop the final reference.

 */

int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)

int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)

{

{

	int ret = 0;

	int ret = 0;
@@ -2652,12 +2680,6 @@ int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks) 
		if (!aborted || tas)

		if (!aborted || tas)

			ret = target_put_sess_cmd(cmd);

			ret = target_put_sess_cmd(cmd);

	}

	}

	/*

	 * If the task has been internally aborted due to TMR ABORT_TASK

	 * or LUN_RESET, target_core_tmr.c is responsible for performing

	 * the remaining calls to target_put_sess_cmd(), and not the

	 * callers of this function.

	 */

	if (aborted) {

	if (aborted) {

		pr_debug("Detected CMD_T_ABORTED for ITT: %llu\n", cmd->tag);

		pr_debug("Detected CMD_T_ABORTED for ITT: %llu\n", cmd->tag);

		wait_for_completion(&cmd->cmd_wait_comp);

		wait_for_completion(&cmd->cmd_wait_comp);