SCSI: scsi_transport_fc: Fix synchronization issue while deleting vport

commit 0d9dc7c8b9b7fa0f53647423b41056ee1beed735 upstream.

The issue occur while deleting 60 virtual ports through the sys
interface /sys/class/fc_vports/vport-X/vport_delete. It happen while in
a mistake each request sent twice for the same vport. This interface is
asynchronous, entering the delete request into a work queue, allowing
more than one request to enter to the delete work queue. The result is a
NULL pointer. The first request already delete the vport, while the
second request got a pointer to the vport before the device destroyed.
Re-create vport later cause system freeze.

Solution: Check vport flags before entering the request to the work queue.

[jejb: fixed int<->long problem on spinlock flags variable]
Signed-off-by: Gal Rosen <galr@storwize.com>
Acked-by: James Smart <james.smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 12 insertions, 12 deletions

diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index 653f22a8deb9..bb8fd5b00955 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -1216,6 +1216,15 @@ store_fc_vport_delete(struct device *dev, struct device_attribute *attr,
 {
         struct fc_vport *vport = transport_class_to_vport(dev);
         struct Scsi_Host *shost = vport_to_shost(vport);
+        unsigned long flags;
+
+        spin_lock_irqsave(shost->host_lock, flags);
+        if (vport->flags & (FC_VPORT_DEL | FC_VPORT_CREATING)) {
+                spin_unlock_irqrestore(shost->host_lock, flags);
+                return -EBUSY;
+        }
+        vport->flags |= FC_VPORT_DELETING;
+        spin_unlock_irqrestore(shost->host_lock, flags);
 
         fc_queue_work(shost, &vport->vport_delete_work);
         return count;
@@ -1805,6 +1814,9 @@ store_fc_host_vport_delete(struct device *dev, struct device_attribute *attr,
         list_for_each_entry(vport, &fc_host->vports, peers) {
                 if ((vport->channel == 0) &&
                     (vport->port_name == wwpn) && (vport->node_name == wwnn)) {
+                        if (vport->flags & (FC_VPORT_DEL | FC_VPORT_CREATING))
+                                break;
+                        vport->flags |= FC_VPORT_DELETING;
                         match = 1;
                         break;
                 }
@@ -3354,18 +3366,6 @@ fc_vport_terminate(struct fc_vport *vport)
         unsigned long flags;
         int stat;
 
-        spin_lock_irqsave(shost->host_lock, flags);
-        if (vport->flags & FC_VPORT_CREATING) {
-                spin_unlock_irqrestore(shost->host_lock, flags);
-                return -EBUSY;
-        }
-        if (vport->flags & (FC_VPORT_DEL)) {
-                spin_unlock_irqrestore(shost->host_lock, flags);
-                return -EALREADY;
-        }
-        vport->flags |= FC_VPORT_DELETING;
-        spin_unlock_irqrestore(shost->host_lock, flags);
-
         if (i->f->vport_delete)
                 stat = i->f->vport_delete(vport);
         else