Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760480Ab3GaSeI (ORCPT ); Wed, 31 Jul 2013 14:34:08 -0400 Received: from smtp-fw-2101.amazon.com ([72.21.196.25]:49779 "EHLO smtp-fw-2101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752554Ab3GaSeF (ORCPT ); Wed, 31 Jul 2013 14:34:05 -0400 X-IronPort-AV: E=Sophos;i="4.89,788,1367971200"; d="scan'208";a="587515854" Date: Wed, 31 Jul 2013 11:33:59 -0700 From: Matt Wilson To: Roger Pau Monne CC: , , David Vrabel Subject: Re: [PATCH 1/3] xen-gnt: prevent adding duplicate gnt callbacks Message-ID: <20130731183358.GD4239@u109add4315675089e695.ant.amazon.com> References: <1375282844-4314-1-git-send-email-roger.pau@citrix.com> <1375282844-4314-2-git-send-email-roger.pau@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1375282844-4314-2-git-send-email-roger.pau@citrix.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1859 Lines: 51 On Wed, Jul 31, 2013 at 05:00:42PM +0200, Roger Pau Monne wrote: > 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. Acked-by: Matt Wilson > Signed-off-by: Roger Pau Monn? > Cc: Konrad Rzeszutek Wilk > Cc: David Vrabel > --- > This patch should be backported to stable trees > --- > drivers/xen/grant-table.c | 13 +++++++++++-- > 1 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c > index 04c1b2d..d5418c1 100644 > --- a/drivers/xen/grant-table.c > +++ b/drivers/xen/grant-table.c > @@ -729,9 +729,18 @@ void gnttab_request_free_callback(struct gnttab_free_callback *callback, > 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/