Commit ccefd23e authored Feb 10, 2012 by Robert Love Committed by James Bottomley Feb 19, 2012

[SCSI] fcoe: Do not switch context in vport_delete callback



Currently all port deletion is routed though the FCoE
workqueue (fcoe_wq). When fc_remove_host is called on
an N_Port (for example, from fcoe_destroy) the vports
are queued into a FC Transport workqueue. fc_remove_host
flushes that queue and each vport is passed to fcoe's
fcoe_vport_destroy, which simply queues the associated
fcoe_ports for later deletion. This queue cannot be
flushed within the N_Ports destroy path because of
circular locking issues. The result is that the NPIV
ports are destroyed after the N_Port, which is reverse
of how they are created.

This quirk causes fcoe to keep references on the
fcoe_interface shared by each of these ports (N_Port
and NPIV). Changing the ordering such that NPIV ports
are destroyed before the N_Port will allow us to remove
reference counting on the fcoe_interface instances.

This patch simply allows fcoe_vport_destory to destroy
NPIV ports without deferring them to a workqueue context.
This ensures that when fc_remove_host is called the
NPIV ports will be destroyed first before the N_Port and
allows reference counting on the fcoe's fcoe_interface
to be remove in a later patch.

Signed-off-by: Robert Love <robert.w.love@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

parent 6f68794c

drivers/scsi/fcoe/fcoe.c

+6 −9

Original line number	Diff line number	Diff line
		@@ -2107,19 +2107,13 @@ static void fcoe_destroy_work(struct work_struct *work)
		{
		struct fcoe_port *port;
		struct fcoe_interface *fcoe;
		int npiv = 0;

		port = container_of(work, struct fcoe_port, destroy_work);
		mutex_lock(&fcoe_config_mutex);

		/* set if this is an NPIV port */
		npiv = port->lport->vport ? 1 : 0;

		fcoe = port->priv;
		fcoe_if_destroy(port->lport);

		/* Do not tear down the fcoe interface for NPIV port */
		if (!npiv)
		fcoe_interface_cleanup(fcoe);

		mutex_unlock(&fcoe_config_mutex);
		@@ -2691,12 +2685,15 @@ static int fcoe_vport_destroy(struct fc_vport *vport)
		struct Scsi_Host *shost = vport_to_shost(vport);
		struct fc_lport *n_port = shost_priv(shost);
		struct fc_lport *vn_port = vport->dd_data;
		struct fcoe_port *port = lport_priv(vn_port);

		mutex_lock(&n_port->lp_mutex);
		list_del(&vn_port->list);
		mutex_unlock(&n_port->lp_mutex);
		queue_work(fcoe_wq, &port->destroy_work);

		mutex_lock(&fcoe_config_mutex);
		fcoe_if_destroy(vn_port);
		mutex_unlock(&fcoe_config_mutex);

		return 0;
		}

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