target: Remove legacy t_fe_count + avoid t_state_lock access in transport_put_cmd

This patch removes legacy se_cmd->t_fe_count usage in order to avoid
se_cmd->t_state_lock access within transport_put_cmd() during normal
fast path se_cmd descriptor release.

Also drop the left-over parameter usage within core_tmr_handle_tas_abort()

Cc: Christoph Hellwig <hch@lst.de>
Cc: Roland Dreier <roland@kernel.org>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Cc: Moussa Ba <moussaba@micron.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_tmr.c

@@ -85,13 +85,8 @@ void core_tmr_release_req(
 static void core_tmr_handle_tas_abort(
 	struct se_node_acl *tmr_nacl,
 	struct se_cmd *cmd,
-	int tas,
-	int fe_count)
+	int tas)
 {
-	if (!fe_count) {
-		transport_cmd_finish_abort(cmd, 1);
-		return;
-	}
 	/*
 	 * TASK ABORTED status (TAS) bit support
 	*/
@@ -253,7 +248,6 @@ static void core_tmr_drain_state_list(
 	LIST_HEAD(drain_task_list);
 	struct se_cmd *cmd, *next;
 	unsigned long flags;
-	int fe_count;
 
 	/*
 	 * Complete outstanding commands with TASK_ABORTED SAM status.
@@ -329,12 +323,10 @@ static void core_tmr_drain_state_list(
 		spin_lock_irqsave(&cmd->t_state_lock, flags);
 		target_stop_cmd(cmd, &flags);
 
-		fe_count = atomic_read(&cmd->t_fe_count);
-
 		cmd->transport_state |= CMD_T_ABORTED;
 		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
 
-		core_tmr_handle_tas_abort(tmr_nacl, cmd, tas, fe_count);
+		core_tmr_handle_tas_abort(tmr_nacl, cmd, tas);
 	}
 }
 

drivers/target/target_core_transport.c

@@ -1968,21 +1968,6 @@ static int transport_release_cmd(struct se_cmd *cmd)
  */
 static int transport_put_cmd(struct se_cmd *cmd)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&cmd->t_state_lock, flags);
-	if (atomic_read(&cmd->t_fe_count) &&
-	    !atomic_dec_and_test(&cmd->t_fe_count)) {
-		spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-		return 0;
-	}
-
-	if (cmd->transport_state & CMD_T_DEV_ACTIVE) {
-		cmd->transport_state &= ~CMD_T_DEV_ACTIVE;
-		target_remove_from_state_list(cmd);
-	}
-	spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-
 	transport_free_pages(cmd);
 	return transport_release_cmd(cmd);
 }
@@ -2100,9 +2085,6 @@ transport_generic_new_cmd(struct se_cmd *cmd)
 		if (ret < 0)
 			return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 	}
-
-	atomic_inc(&cmd->t_fe_count);
-
 	/*
 	 * If this command is not a write we can execute it right here,
 	 * for write buffers we need to notify the fabric driver first

include/target/target_core_base.h

@@ -454,7 +454,6 @@ struct se_cmd {
 	unsigned char		*t_task_cdb;
 	unsigned char		__t_task_cdb[TCM_MAX_COMMAND_SIZE];
 	unsigned long long	t_task_lba;
-	atomic_t		t_fe_count;
 	unsigned int		transport_state;
 #define CMD_T_ABORTED		(1 << 0)
 #define CMD_T_ACTIVE		(1 << 1)