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From: Greg KH on 30 Mar 2010 19:50
2.6.33-stable review patch. If anyone has any objections, please let us know.

------------------

From: Gal Rosen <galr(a)storwize.com>

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(a)storwize.com>
Acked-by: James Smart <james.smart(a)emulex.com>
Signed-off-by: James Bottomley <James.Bottomley(a)suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>

---
drivers/scsi/scsi_transport_fc.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)

--- 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 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
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 *vpor
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


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Prev: [048/156] gigaset: correct range checking off by one error
Next: [050/156] perf: Make the install relative to DESTDIR if specified