xen-gnt: prevent adding duplicate gnt callbacks
authorRoger Pau Monne <roger.pau@citrix.com>
Wed, 31 Jul 2013 15:00:42 +0000 (17:00 +0200)
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Fri, 9 Aug 2013 14:58:11 +0000 (10:58 -0400)
commit5f338d9001094a56cf87bd8a280b4e7ff953bb59
treedaef4ba1e3c1ecfa3e6dc8f87a21197911f78fc2
parente2683957fb268c6b29316fd9e7191e13239a30a5
xen-gnt: prevent adding duplicate gnt callbacks

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@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Matt Wilson <msw@amazon.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
CC: stable@vger.kernel.org
drivers/xen/grant-table.c