[fc] Maintain a list of Fibre Channel upper-layer protocol users

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/fc.h

 
 	/** List of upper-layer protocols */
 	struct list_head ulps;
-	/** Active usage count */
+	/** Active usage count
+	 *
+	 * A peer (and attached ULPs) may be created in response to
+	 * unsolicited login requests received via the fabric.  We
+	 * track our own active usage count independently of the
+	 * existence of the peer, so that if the peer becomes logged
+	 * out (e.g. due to a link failure) then we know whether or
+	 * not we should attempt to relogin.
+	 */
 	unsigned int usage;
 };
 
 	/** Service parameter length */
 	size_t param_len;
 
-	/** Active usage count */
-	unsigned int usage;
+	/** Active users of this upper-layer protocol
+	 *
+	 * As with peers, an upper-layer protocol may be created in
+	 * response to an unsolicited login request received via the
+	 * fabric.  This list records the number of active users of
+	 * the ULP; the number of entries in the list is equivalent to
+	 * the peer usage count.
+	 */
+	struct list_head users;
 };
 
 /** Fibre Channel upper-layer protocol flags */
 	FC_ULP_ORIGINATED_LOGIN_OK = 0x0001,
 };
 
+/** A Fibre Channel upper-layer protocol user */
+struct fc_ulp_user {
+	/** Fibre Channel upper layer protocol */
+	struct fc_ulp *ulp;
+	/** List of users */
+	struct list_head list;
+};
+
 /**
  * Get reference to Fibre Channel upper-layer protocol
  *
 fc_ulp_get_port_id_type ( struct fc_port *port,
 			  const struct fc_port_id *peer_port_id,
 			  unsigned int type );
-extern void fc_ulp_increment ( struct fc_ulp *ulp );
-extern void fc_ulp_decrement ( struct fc_ulp *ulp );
+extern void fc_ulp_attach ( struct fc_ulp *ulp, struct fc_ulp_user *user );
+extern void fc_ulp_detach ( struct fc_ulp_user *user );
 extern int fc_ulp_login ( struct fc_ulp *ulp, const void *param,
 			  size_t param_len, int originated );
 extern void fc_ulp_logout ( struct fc_ulp *ulp, int rc );

src/net/fc.c

 	       fc_ntoa ( &ulp->peer->port_wwn ), ulp->type, strerror ( rc ) );
 
 	/* Sanity check */
-	assert ( ulp->usage == 0 );
+	assert ( list_empty ( &ulp->users ) );
 
 	/* Stop link monitor */
 	fc_link_stop ( &ulp->link );
 }
 
 /**
- * Increment Fibre Channel upper-layer protocol active usage count
+ * Attach Fibre Channel upper-layer protocol user
  *
- * @v ulp		Fibre Channel ulp
+ * @v ulp		Fibre Channel upper-layer protocol
+ * @v user		Fibre Channel upper-layer protocol user
  */
-void fc_ulp_increment ( struct fc_ulp *ulp ) {
+void fc_ulp_attach ( struct fc_ulp *ulp, struct fc_ulp_user *user ) {
+
+	/* Sanity check */
+	assert ( user->ulp == NULL );
 
 	/* Increment peer's usage count */
 	fc_peer_increment ( ulp->peer );
 
-	/* Increment our usage count */
-	ulp->usage++;
+	/* Attach user */
+	user->ulp = fc_ulp_get ( ulp );
+	list_add ( &user->list, &ulp->users );
 }
 
 /**
- * Decrement Fibre Channel upper-layer protocol active usage count
+ * Detach Fibre Channel upper-layer protocol user
  *
- * @v ulp		Fibre Channel ulp
+ * @v user		Fibre Channel upper-layer protocol user
  */
-void fc_ulp_decrement ( struct fc_ulp *ulp ) {
+void fc_ulp_detach ( struct fc_ulp_user *user ) {
+	struct fc_ulp *ulp = user->ulp;
 
-	/* Sanity check */
-	assert ( ulp->usage > 0 );
+	/* Do nothing if not attached */
+	if ( ! ulp )
+		return;
 
-	/* Decrement our usage count and log out if we reach zero */
-	if ( --(ulp->usage) == 0 )
+	/* Sanity checks */
+	list_check_contains ( user, &ulp->users, list );
+
+	/* Detach user and log out if no users remain */
+	list_del ( &user->list );
+	if ( list_empty ( &ulp->users ) )
 		fc_ulp_logout ( ulp, 0 );
 
 	/* Decrement our peer's usage count */
 	fc_peer_decrement ( ulp->peer );
+
+	/* Drop reference */
+	user->ulp = NULL;
+	fc_ulp_put ( ulp );
 }
 
 /**
 	fc_link_err ( &ulp->link, rc );
 
 	/* Close ULP if there are no clients attached */
-	if ( ulp->usage == 0 )
+	if ( list_empty ( &ulp->users ) )
 		fc_ulp_close ( ulp, rc );
 }
 
 	ulp->peer = fc_peer_get ( peer );
 	list_add_tail ( &ulp->list, &peer->ulps );
 	ulp->type = type;
+	INIT_LIST_HEAD ( &ulp->users );
 
 	/* Start link state monitor */
 	fc_link_start ( &ulp->link );

src/net/fcp.c

 struct fcp_device {
 	/** Reference count */
 	struct refcnt refcnt;
-	/** Fibre Channel upper-layer protocol */
-	struct fc_ulp *ulp;
+	/** Fibre Channel upper-layer protocol user */
+	struct fc_ulp_user user;
 	/** SCSI command issuing interface */
 	struct interface scsi;
 	/** List of active commands */
 static int fcpdev_scsi_command ( struct fcp_device *fcpdev,
 				 struct interface *parent,
 				 struct scsi_cmd *command ) {
-	struct fcp_prli_service_parameters *param = fcpdev->ulp->param;
+	struct fcp_prli_service_parameters *param = fcpdev->user.ulp->param;
 	struct fcp_command *fcpcmd;
 	int xchg_id;
 	int rc;
 
 	/* Check link */
-	if ( ( rc = fcpdev->ulp->link.rc ) != 0 ) {
+	if ( ( rc = fcpdev->user.ulp->link.rc ) != 0 ) {
 		DBGC ( fcpdev, "FCP %p could not issue command while link is "
 		       "down: %s\n", fcpdev, strerror ( rc ) );
 		goto err_link;
 
 	/* Check target capability */
 	assert ( param != NULL );
-	assert ( fcpdev->ulp->param_len >= sizeof ( *param ) );
+	assert ( fcpdev->user.ulp->param_len >= sizeof ( *param ) );
 	if ( ! ( param->flags & htonl ( FCP_PRLI_TARGET ) ) ) {
 		DBGC ( fcpdev, "FCP %p could not issue command: not a target\n",
 		       fcpdev );
 
 	/* Create new exchange */
 	if ( ( xchg_id = fc_xchg_originate ( &fcpcmd->xchg,
-					     fcpdev->ulp->peer->port,
-					     &fcpdev->ulp->peer->port_id,
+					     fcpdev->user.ulp->peer->port,
+					     &fcpdev->user.ulp->peer->port_id,
 					     FC_TYPE_FCP ) ) < 0 ) {
 		rc = xchg_id;
 		DBGC ( fcpdev, "FCP %p could not create exchange: %s\n",
 	}
 
 	/* Drop reference to ULP */
-	if ( fcpdev->ulp ) {
-		fc_ulp_decrement ( fcpdev->ulp );
-		fc_ulp_put ( fcpdev->ulp );
-		fcpdev->ulp = NULL;
-	}
+	fc_ulp_detach ( &fcpdev->user );
 }
 
 /**
  * @ret len		Length of window
  */
 static size_t fcpdev_window ( struct fcp_device *fcpdev ) {
-	return ( fc_link_ok ( &fcpdev->ulp->link ) ? ~( ( size_t ) 0 ) : 0 );
+	return ( fc_link_ok ( &fcpdev->user.ulp->link ) ?
+		 ~( ( size_t ) 0 ) : 0 );
 }
 
 /**
 	/* We know the underlying device only if the link is up;
 	 * otherwise we don't have a port to examine.
 	 */
-	if ( ! fc_link_ok ( &fcpdev->ulp->link ) ) {
+	if ( ! fc_link_ok ( &fcpdev->user.ulp->link ) ) {
 		DBGC ( fcpdev, "FCP %p doesn't know underlying device "
 		       "until link is up\n", fcpdev );
 		return NULL;
 	}
 
 	/* Hand off to port's transport interface */
-	assert ( fcpdev->ulp->peer->port != NULL );
-	return identify_device ( &fcpdev->ulp->peer->port->transport );
+	assert ( fcpdev->user.ulp->peer->port != NULL );
+	return identify_device ( &fcpdev->user.ulp->peer->port->transport );
 }
 
 /** FCP device SCSI interface operations */
 	ref_init ( &fcpdev->refcnt, NULL );
 	intf_init ( &fcpdev->scsi, &fcpdev_scsi_desc, &fcpdev->refcnt );
 	INIT_LIST_HEAD ( &fcpdev->fcpcmds );
-	fcpdev->ulp = fc_ulp_get ( ulp );
-	fc_ulp_increment ( fcpdev->ulp );
+	fc_ulp_attach ( ulp, &fcpdev->user );
 
 	DBGC ( fcpdev, "FCP %p opened for %s\n", fcpdev, fc_ntoa ( wwn ) );
 

src/usr/fcmgmt.c

 	}
 
 	list_for_each_entry ( ulp, &peer->ulps, list ) {
-		printf ( "  [Type %02x usage %d link:",
-			 ulp->type, ulp->usage );
+		printf ( "  [Type %02x link:", ulp->type );
 		if ( fc_link_ok ( &ulp->link ) ) {
 			printf ( " up, params" );
 			param = ulp->param;