scsi: iscsi: Add recv workqueue helpers

Add helpers to allow the drivers to run their recv paths from libiscsi's
workqueue.

Link: https://lore.kernel.org/r/20220616224557.115234-3-michael.christie@oracle.comReviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/libiscsi.c

@@ -93,6 +93,16 @@ inline void iscsi_conn_queue_xmit(struct iscsi_conn *conn)
 }
 EXPORT_SYMBOL_GPL(iscsi_conn_queue_xmit);
 
+inline void iscsi_conn_queue_recv(struct iscsi_conn *conn)
+{
+	struct Scsi_Host *shost = conn->session->host;
+	struct iscsi_host *ihost = shost_priv(shost);
+
+	if (ihost->workq && !test_bit(ISCSI_CONN_FLAG_SUSPEND_RX, &conn->flags))
+		queue_work(ihost->workq, &conn->recvwork);
+}
+EXPORT_SYMBOL_GPL(iscsi_conn_queue_recv);
+
 static void __iscsi_update_cmdsn(struct iscsi_session *session,
 				 uint32_t exp_cmdsn, uint32_t max_cmdsn)
 {
@@ -1947,7 +1957,7 @@ EXPORT_SYMBOL_GPL(iscsi_suspend_queue);
 
 /**
  * iscsi_suspend_tx - suspend iscsi_data_xmit
- * @conn: iscsi conn tp stop processing IO on.
+ * @conn: iscsi conn to stop processing IO on.
  *
  * This function sets the suspend bit to prevent iscsi_data_xmit
  * from sending new IO, and if work is queued on the xmit thread
@@ -1960,7 +1970,7 @@ void iscsi_suspend_tx(struct iscsi_conn *conn)
 
 	set_bit(ISCSI_CONN_FLAG_SUSPEND_TX, &conn->flags);
 	if (ihost->workq)
-		flush_workqueue(ihost->workq);
+		flush_work(&conn->xmitwork);
 }
 EXPORT_SYMBOL_GPL(iscsi_suspend_tx);
 
@@ -1970,6 +1980,21 @@ static void iscsi_start_tx(struct iscsi_conn *conn)
 	iscsi_conn_queue_xmit(conn);
 }
 
+/**
+ * iscsi_suspend_rx - Prevent recvwork from running again.
+ * @conn: iscsi conn to stop.
+ */
+void iscsi_suspend_rx(struct iscsi_conn *conn)
+{
+	struct Scsi_Host *shost = conn->session->host;
+	struct iscsi_host *ihost = shost_priv(shost);
+
+	set_bit(ISCSI_CONN_FLAG_SUSPEND_RX, &conn->flags);
+	if (ihost->workq)
+		flush_work(&conn->recvwork);
+}
+EXPORT_SYMBOL_GPL(iscsi_suspend_rx);
+
 /*
  * We want to make sure a ping is in flight. It has timed out.
  * And we are not busy processing a pdu that is making

include/scsi/libiscsi.h

@@ -213,6 +213,8 @@ struct iscsi_conn {
 	struct list_head	cmdqueue;	/* data-path cmd queue */
 	struct list_head	requeue;	/* tasks needing another run */
 	struct work_struct	xmitwork;	/* per-conn. xmit workqueue */
+	/* recv */
+	struct work_struct	recvwork;
 	unsigned long		flags;		/* ISCSI_CONN_FLAGs */
 
 	/* negotiated params */
@@ -452,8 +454,10 @@ extern int iscsi_conn_get_param(struct iscsi_cls_conn *cls_conn,
 extern int iscsi_conn_get_addr_param(struct sockaddr_storage *addr,
 				     enum iscsi_param param, char *buf);
 extern void iscsi_suspend_tx(struct iscsi_conn *conn);
+extern void iscsi_suspend_rx(struct iscsi_conn *conn);
 extern void iscsi_suspend_queue(struct iscsi_conn *conn);
 extern void iscsi_conn_queue_xmit(struct iscsi_conn *conn);
+extern void iscsi_conn_queue_recv(struct iscsi_conn *conn);
 
 #define iscsi_conn_printk(prefix, _c, fmt, a...) \
 	iscsi_cls_conn_printk(prefix, ((struct iscsi_conn *)_c)->cls_conn, \