target: Make TFO->check_stop_free return free status

This patch converts target_core_fabric_ops->check_stop_free() usage in
transport_cmd_check_stop() and associated fabric module usage to
return '1' when the passed se_cmd has been released directly within
->check_stop_free(), or return '0' when the passed se_cmd has not
been released.

This addresses an issue where transport_cmd_finish_abort() ->
transport_cmd_check_stop_to_fabric() was leaking descriptors during
LUN_RESET for modules using ->check_stop_free(), but not directly
releasing se_cmd in all cases.

Cc: stable@kernel.org
Signed-off-by: Nicholas Bellinger <nab@risingtidesystems.com>

drivers/target/loopback/tcm_loop.c

@@ -205,7 +205,7 @@ static int tcm_loop_new_cmd_map(struct se_cmd *se_cmd)
 /*
  * Called from struct target_core_fabric_ops->check_stop_free()
  */
-static void tcm_loop_check_stop_free(struct se_cmd *se_cmd)
+static int tcm_loop_check_stop_free(struct se_cmd *se_cmd)
 {
 	/*
 	 * Do not release struct se_cmd's containing a valid TMR
@@ -213,12 +213,13 @@ static void tcm_loop_check_stop_free(struct se_cmd *se_cmd)
 	 * with transport_generic_free_cmd().
 	 */
 	if (se_cmd->se_tmr_req)
-		return;
+		return 0;
 	/*
 	 * Release the struct se_cmd, which will make a callback to release
 	 * struct tcm_loop_cmd * in tcm_loop_deallocate_core_cmd()
 	 */
 	transport_generic_free_cmd(se_cmd, 0);
+	return 1;
 }
 
 static void tcm_loop_release_cmd(struct se_cmd *se_cmd)

drivers/target/target_core_transport.c

@@ -514,13 +514,16 @@ static int transport_cmd_check_stop(
 			 * Some fabric modules like tcm_loop can release
 			 * their internally allocated I/O reference now and
 			 * struct se_cmd now.
+			 *
+			 * Fabric modules are expected to return '1' here if the
+			 * se_cmd being passed is released at this point,
+			 * or zero if not being released.
 			 */
 			if (cmd->se_tfo->check_stop_free != NULL) {
 				spin_unlock_irqrestore(
 					&cmd->t_state_lock, flags);
 
-				cmd->se_tfo->check_stop_free(cmd);
-				return 1;
+				return cmd->se_tfo->check_stop_free(cmd);
 			}
 		}
 		spin_unlock_irqrestore(&cmd->t_state_lock, flags);

drivers/target/tcm_fc/tcm_fc.h

@@ -156,7 +156,7 @@ int ft_lport_notify(struct notifier_block *, unsigned long, void *);
 /*
  * IO methods.
  */
-void ft_check_stop_free(struct se_cmd *);
+int ft_check_stop_free(struct se_cmd *);
 void ft_release_cmd(struct se_cmd *);
 int ft_queue_status(struct se_cmd *);
 int ft_queue_data_in(struct se_cmd *);

drivers/target/tcm_fc/tfc_cmd.c

@@ -112,9 +112,10 @@ void ft_release_cmd(struct se_cmd *se_cmd)
 	ft_free_cmd(cmd);
 }
 
-void ft_check_stop_free(struct se_cmd *se_cmd)
+int ft_check_stop_free(struct se_cmd *se_cmd)
 {
 	transport_generic_free_cmd(se_cmd, 0);
+	return 1;
 }
 
 /*

include/target/target_core_fabric_ops.h

@@ -46,9 +46,12 @@ struct target_core_fabric_ops {
 	int (*new_cmd_map)(struct se_cmd *);
 	/*
 	 * Optional to release struct se_cmd and fabric dependent allocated
-	 * I/O descriptor in transport_cmd_check_stop()
+	 * I/O descriptor in transport_cmd_check_stop().
+	 *
+	 * Returning 1 will signal a descriptor has been released.
+	 * Returning 0 will signal a descriptor has not been released.
 	 */
-	void (*check_stop_free)(struct se_cmd *);
+	int (*check_stop_free)(struct se_cmd *);
 	void (*release_cmd)(struct se_cmd *);
 	/*
 	 * Called with spin_lock_bh(struct se_portal_group->session_lock held.