linux-kernel - [058/156] SCSI: scsi_transport_fc: Fix synchronization issue while deleting vport

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Message-Id: <20100330224758.272422399@linux.site>
Date:	Tue, 30 Mar 2010 15:41:32 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Gal Rosen <galr@...rwize.com>,
	James Smart <james.smart@...lex.com>,
	James Bottomley <James.Bottomley@...e.de>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: [058/156] SCSI: scsi_transport_fc: Fix synchronization issue while deleting vport

2.6.33-stable review patch.  If anyone has any objections, please let us know.

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

From: Gal Rosen <galr@...rwize.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@...rwize.com>
Acked-by: James Smart <james.smart@...lex.com>
Signed-off-by: James Bottomley <James.Bottomley@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.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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