linux-kernel - Re: [PATCH] media: v4l2-async: Put fwnode after last access

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Message-ID: <2c6c885efbfc7569f280e9ebd0aa307b56fd7901.camel@collabora.com>
Date:   Mon, 28 Dec 2020 13:51:29 -0300
From:   Ezequiel Garcia <ezequiel@...labora.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel@...labora.com, Hans Verkuil <hverkuil@...all.nl>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
Subject: Re: [PATCH] media: v4l2-async: Put fwnode after last access

On Mon, 2020-12-28 at 15:16 +0200, Laurent Pinchart wrote:
> Hi Ezequiel,
> 
> Thank you for the patch.
> 
> On Mon, Dec 28, 2020 at 09:17:25AM -0300, Ezequiel Garcia wrote:
> > fwnode_handle_put() should be called after the fwnode
> > is last accessed. Fix it.
> > 
> > Fixes: b98158d837ef ("media: v4l2-async: Accept endpoints and devices for fwnode matching")
> > Signed-off-by: Ezequiel Garcia <ezequiel@...labora.com>
> > ---
> >  drivers/media/v4l2-core/v4l2-async.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> > index e3ab003a6c85..1303c9b83138 100644
> > --- a/drivers/media/v4l2-core/v4l2-async.c
> > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > @@ -78,6 +78,7 @@ static bool match_fwnode(struct v4l2_async_notifier *notifier,
> >         bool asd_fwnode_is_ep;
> >         bool sd_fwnode_is_ep;
> >         struct device *dev;
> > +       bool match;
> >  
> >         /*
> >          * Both the subdev and the async subdev can provide either an endpoint
> > @@ -113,9 +114,10 @@ static bool match_fwnode(struct v4l2_async_notifier *notifier,
> >                 other_fwnode = sd->fwnode;
> >         }
> >  
> > -       fwnode_handle_put(dev_fwnode);
> > +       match = (dev_fwnode == other_fwnode);
> >  
> > -       if (dev_fwnode != other_fwnode)
> 
> This only performs a pointer comparison, it doesn't access dev_fwnode. I
> don't think the change is necessary.
> 

Ah, of course. I'm always confused by this.

Thanks,
Ezequiel