Re: [PATCH 2/2] target: iscsi: fix a race condition when aborting a task

[Maurizio Lombardi <mlombard@xxxxxxxxxx>]

Dne 28. 10. 20 v 21:37 Mike Christie napsal(a):
>>
>> Possible solutions that I can think of:
>>
>> - Make iscsit_release_commands_from_conn() wait for the abort task to finish
> 
> Yeah you could set a completion in there then have aborted_task do the complete() call maybe?
> 

We could do something like this, what do you think?

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 067074ef50818..ffd3dbc53a42f 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -490,13 +490,16 @@ EXPORT_SYMBOL(iscsit_queue_rsp);
 
 void iscsit_aborted_task(struct iscsi_conn *conn, struct iscsi_cmd *cmd)
 {
+	struct se_cmd *se_cmd = cmd->se_cmd.se_tfo ? &cmd->se_cmd : NULL;
+
 	spin_lock_bh(&conn->cmd_lock);
-	if (!list_empty(&cmd->i_conn_node) &&
-	    !(cmd->se_cmd.transport_state & CMD_T_FABRIC_STOP))
+	if (!list_empty(&cmd->i_conn_node))
 		list_del_init(&cmd->i_conn_node);
 	spin_unlock_bh(&conn->cmd_lock);
 
 	__iscsit_free_cmd(cmd, true);
+	if (se_cmd && se_cmd->abrt_task_compl)
+		complete(se_cmd->abrt_task_compl);
 }
 EXPORT_SYMBOL(iscsit_aborted_task);
 
@@ -4080,6 +4083,7 @@ int iscsi_target_rx_thread(void *arg)
 
 static void iscsit_release_commands_from_conn(struct iscsi_conn *conn)
 {
+	DECLARE_COMPLETION_ONSTACK(compl);
 	LIST_HEAD(tmp_list);
 	struct iscsi_cmd *cmd = NULL, *cmd_tmp = NULL;
 	struct iscsi_session *sess = conn->sess;
@@ -4096,8 +4100,24 @@ static void iscsit_release_commands_from_conn(struct iscsi_conn *conn)
 
 		if (se_cmd->se_tfo != NULL) {
 			spin_lock_irq(&se_cmd->t_state_lock);
+			if (se_cmd->transport_state & CMD_T_ABORTED) {
+				/*
+				 * LIO's abort path owns the cleanup for this,
+				 * so put it back on the list and let
+				 * aborted_task handle it.
+				 */
+				list_move_tail(&cmd->i_conn_node, &conn->conn_cmd_list);
+				WARN_ON_ONCE(se_cmd->abrt_task_compl);
+				se_cmd->abrt_task_compl = &compl;
+			}
 			se_cmd->transport_state |= CMD_T_FABRIC_STOP;
 			spin_unlock_irq(&se_cmd->t_state_lock);
+
+			if (se_cmd->abrt_task_compl) {
+				spin_unlock_bh(&conn->cmd_lock);
+				wait_for_completion(&compl);
+				spin_lock_bh(&conn->cmd_lock);
+			}
 		}
 	}
 	spin_unlock_bh(&conn->cmd_lock);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index db53a0d649da7..5611e6c00f18c 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1391,6 +1391,7 @@ void transport_init_se_cmd(
 	init_completion(&cmd->t_transport_stop_comp);
 	cmd->free_compl = NULL;
 	cmd->abrt_compl = NULL;
+	cmd->abrt_task_compl = NULL;
 	spin_lock_init(&cmd->t_state_lock);
 	INIT_WORK(&cmd->work, NULL);
 	kref_init(&cmd->cmd_kref);
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 549947d407cfd..25cc451930281 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -491,6 +491,7 @@ struct se_cmd {
 	struct list_head	se_cmd_list;
 	struct completion	*free_compl;
 	struct completion	*abrt_compl;
+	struct completion	*abrt_task_compl;
 	const struct target_core_fabric_ops *se_tfo;
 	sense_reason_t		(*execute_cmd)(struct se_cmd *);
 	sense_reason_t (*transport_complete_callback)(struct se_cmd *, bool, int *);
-- 
2.26.2