linux-kernel - Re: [PATCH v3 1/8] [media] soc_camera: Do not decrement endpoint node refcount in the loop

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Message-ID: <1411630851.5671.2.camel@pengutronix.de>
Date:	Thu, 25 Sep 2014 09:40:51 +0200
From:	Philipp Zabel <p.zabel@...gutronix.de>
To:	Guennadi Liakhovetski <g.liakhovetski@....de>
Cc:	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	devel@...verdev.osuosl.org, Grant Likely <grant.likely@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Mauro Carvalho Chehab <m.chehab@...sung.com>,
	Russell King <rmk+kernel@....linux.org.uk>,
	kernel@...gutronix.de
Subject: Re: [PATCH v3 1/8] [media] soc_camera: Do not decrement endpoint
 node refcount in the loop

Hi Guennadi,

Am Samstag, den 20.09.2014, 09:24 +0200 schrieb Guennadi Liakhovetski:
> Hi Philippe,
> 
> On Thu, 11 Sep 2014, Philipp Zabel wrote:
> 
> > In preparation for a following patch, stop decrementing the endpoint node
> > refcount in the loop. This temporarily leaks a reference to the endpoint node,
> > which will be fixed by having of_graph_get_next_endpoint decrement the refcount
> > of its prev argument instead.
> > 
> > Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
> > ---
> >  drivers/media/platform/soc_camera/soc_camera.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/platform/soc_camera/soc_camera.c b/drivers/media/platform/soc_camera/soc_camera.c
> > index f4308fe..f752489 100644
> > --- a/drivers/media/platform/soc_camera/soc_camera.c
> > +++ b/drivers/media/platform/soc_camera/soc_camera.c
> > @@ -1696,11 +1696,11 @@ static void scan_of_host(struct soc_camera_host *ici)
> >  		if (!i)
> >  			soc_of_bind(ici, epn, ren->parent);
> >  
> > -		of_node_put(epn);
> >  		of_node_put(ren);
> >  
> >  		if (i) {
> >  			dev_err(dev, "multiple subdevices aren't supported yet!\n");
> > +			of_node_put(epn);
> 
> Sorry, this doesn't look right to me. I think you want to drop the last 
> reference _after_ the loop, not in this temporary check for multiple 
> endpoints, which your patch has nothing to do with.

Since we only ever break out of the loop here or if epn == NULL, it
won't make a difference. Would you prefer this:

--- a/drivers/media/platform/soc_camera/soc_camera.c
+++ b/drivers/media/platform/soc_camera/soc_camera.c
@@ -1696,7 +1696,6 @@ static void scan_of_host(struct soc_camera_host *ici)
                if (!i)
                        soc_of_bind(ici, epn, ren->parent);
 
-               of_node_put(epn);
                of_node_put(ren);
 
                if (i) {
@@ -1704,6 +1703,8 @@ static void scan_of_host(struct soc_camera_host *ici)
                        break;
                }
        }
+
+       of_node_put(epn);
 }
 
 #else


regards
Philipp

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