From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH v2 06/10] driver core: Avoid endless recursion if device has more than one link Date: Wed, 07 Sep 2016 01:09:36 +0200 Message-ID: <1633380.7F0afK1dbG@vostro.rjw.lan> References: <1466144820-6286-1-git-send-email-m.szyprowski@samsung.com> <1466144820-6286-7-git-send-email-m.szyprowski@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1466144820-6286-7-git-send-email-m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Marek Szyprowski Cc: Krzysztof Kozlowski , linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Greg Kroah-Hartman , Bartlomiej Zolnierkiewicz , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Inki Dae , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Kukjin Kim , Mark Brown , Ulf Hansson , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: linux-samsung-soc@vger.kernel.org On Friday, June 17, 2016 08:26:56 AM Marek Szyprowski wrote: > This patch fixes endless recursion, which happends when device has > more than one link. > > Signed-off-by: Marek Szyprowski > --- > drivers/base/core.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index 215cd44de761..4e778539b750 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -57,7 +57,8 @@ static int device_reorder_to_tail(struct device *dev, void *not_used) > device_pm_move_last(dev); > device_for_each_child(dev, NULL, device_reorder_to_tail); > list_for_each_entry(link, &dev->consumer_links, c_node) > - device_reorder_to_tail(link->consumer, NULL); > + if (link->consumer != dev) > + device_reorder_to_tail(link->consumer, NULL); > > return 0; > } > If I'm not mistaken, this should not be necessary unless dev has a link pointing to itself as a consumer. That would be a bug, though. I can add a WARN_ON() to catch this case, but then if there's a link from a consumer of dev pointing back to dev as a consumer, that still will loop forever. I guess we need to detect circular dependencies and fail link creation in such cases. Oh well. Thanks, Rafael