scsi: target: iscsi: Avoid in_interrupt() usage in iscsit_check_session_usage_count()

iscsit_check_session_usage_count() uses in_interrupt() to find out if it is
safe to invoke wait_for_completion().

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

There is only one caller of iscsit_check_session_usage_count() which
already has an argument indicating if it is safe to sleep.

Extend iscsit_check_session_usage_count() by an argument indicating if it
may sleep.

Link: https://lore.kernel.org/r/20201220203638.43615-3-bigeasy@linutronix.deSigned-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/target/iscsi/iscsi_target.c

@@ -4400,9 +4400,9 @@ int iscsit_close_session(struct iscsi_session *sess, bool can_sleep)
 	 * restart the timer and exit.
 	 */
 	if (can_sleep) {
-		iscsit_check_session_usage_count(sess);
+		iscsit_check_session_usage_count(sess, can_sleep);
 	} else {
-		if (iscsit_check_session_usage_count(sess) == 2) {
+		if (iscsit_check_session_usage_count(sess, can_sleep) == 2) {
 			atomic_set(&sess->session_logout, 0);
 			iscsit_start_time2retain_handler(sess);
 			return 0;

drivers/target/iscsi/iscsi_target_util.c

@@ -779,13 +779,13 @@ void iscsit_free_cmd(struct iscsi_cmd *cmd, bool shutdown)
 }
 EXPORT_SYMBOL(iscsit_free_cmd);
 
-int iscsit_check_session_usage_count(struct iscsi_session *sess)
+int iscsit_check_session_usage_count(struct iscsi_session *sess, bool can_sleep)
 {
 	spin_lock_bh(&sess->session_usage_lock);
 	if (sess->session_usage_count != 0) {
 		sess->session_waiting_on_uc = 1;
 		spin_unlock_bh(&sess->session_usage_lock);
-		if (in_interrupt())
+		if (!can_sleep)
 			return 2;
 
 		wait_for_completion(&sess->session_waiting_on_uc_comp);

drivers/target/iscsi/iscsi_target_util.h

@@ -40,7 +40,7 @@ extern void iscsit_free_queue_reqs_for_conn(struct iscsi_conn *);
 extern void iscsit_release_cmd(struct iscsi_cmd *);
 extern void __iscsit_free_cmd(struct iscsi_cmd *, bool);
 extern void iscsit_free_cmd(struct iscsi_cmd *, bool);
-extern int iscsit_check_session_usage_count(struct iscsi_session *);
+extern int iscsit_check_session_usage_count(struct iscsi_session *sess, bool can_sleep);
 extern void iscsit_dec_session_usage_count(struct iscsi_session *);
 extern void iscsit_inc_session_usage_count(struct iscsi_session *);
 extern struct iscsi_conn *iscsit_get_conn_from_cid(struct iscsi_session *, u16);