Re: [PATCH] drm/drm_lease: Do not call drm_master_put() twice in case drm_lease_create() fails

From: Daniel Vetter <daniel@ffwll.ch>
To: Marius Vlad <marius-cristian.vlad@nxp.com>
Cc: daniel.vetter@ffwll.ch, keithp@keithp.com,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm/drm_lease: Do not call drm_master_put() twice in case drm_lease_create() fails
Date: Tue, 12 Dec 2017 16:30:20 +0100	[thread overview]
Message-ID: <20171212153020.GD526@phenom.ffwll.local> (raw)
In-Reply-To: <20171212120414.8675-1-marius-cristian.vlad@nxp.com>

On Tue, Dec 12, 2017 at 02:04:14PM +0200, Marius Vlad wrote:
> This case can been seen when creating the lease with same objects passed.
> 
> Signed-off-by: Marius Vlad <marius-cristian.vlad@nxp.com>
> ---
>  drivers/gpu/drm/drm_lease.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c
> index d1eb56a..ae57f33 100644
> --- a/drivers/gpu/drm/drm_lease.c
> +++ b/drivers/gpu/drm/drm_lease.c
> @@ -254,8 +254,6 @@ static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr
>  	return lessee;
>  
>  out_lessee:
> -	drm_master_put(&lessee);

I'm not really following here ... the lessee reference we're dropping here
is created in drm_master_create. We're only calling drm_master_put if that
succeeded. Removing this line here looks like now we're leaking.

Where is the double-free? I don't see the 2nd drm_master_put() anywhere
... drm_mode_create_lease_ioctl also seems to be doing the right thing
from just staring at it.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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