Patch "xen-gnt: prevent adding duplicate gnt callbacks" has been added to the 3.11-stable tree

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This is a note to let you know that I've just added the patch titled

    xen-gnt: prevent adding duplicate gnt callbacks

to the 3.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xen-gnt-prevent-adding-duplicate-gnt-callbacks.patch
and it can be found in the queue-3.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 5f338d9001094a56cf87bd8a280b4e7ff953bb59 Mon Sep 17 00:00:00 2001
From: Roger Pau Monne <roger.pau@xxxxxxxxxx>
Date: Wed, 31 Jul 2013 17:00:42 +0200
Subject: xen-gnt: prevent adding duplicate gnt callbacks

From: Roger Pau Monne <roger.pau@xxxxxxxxxx>

commit 5f338d9001094a56cf87bd8a280b4e7ff953bb59 upstream.

With the current implementation, the callback in the tail of the list
can be added twice, because the check done in
gnttab_request_free_callback is bogus, callback->next can be NULL if
it is the last callback in the list. If we add the same callback twice
we end up with an infinite loop, were callback == callback->next.

Replace this check with a proper one that iterates over the list to
see if the callback has already been added.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: David Vrabel <david.vrabel@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Acked-by: Matt Wilson <msw@xxxxxxxxxx>
Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/xen/grant-table.c |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -730,9 +730,18 @@ void gnttab_request_free_callback(struct
 				  void (*fn)(void *), void *arg, u16 count)
 {
 	unsigned long flags;
+	struct gnttab_free_callback *cb;
+
 	spin_lock_irqsave(&gnttab_list_lock, flags);
-	if (callback->next)
-		goto out;
+
+	/* Check if the callback is already on the list */
+	cb = gnttab_free_callback_list;
+	while (cb) {
+		if (cb == callback)
+			goto out;
+		cb = cb->next;
+	}
+
 	callback->fn = fn;
 	callback->arg = arg;
 	callback->count = count;


Patches currently in stable-queue which might be from roger.pau@xxxxxxxxxx are

queue-3.11/xen-gnt-prevent-adding-duplicate-gnt-callbacks.patch
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