linux-kernel - Re: [PATCH v2] drm/lease: fix WARNING in idr

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Date:   Wed, 18 Mar 2020 14:38:52 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Qiujun Huang <hqjagain@...il.com>
Cc:     daniel@...ll.ch, maarten.lankhorst@...ux.intel.com,
        mripard@...nel.org, airlied@...ux.ie,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        anenbupt@...il.com
Subject: Re: [PATCH v2] drm/lease: fix WARNING in idr_destroy

On Wed, Mar 18, 2020 at 03:53:50PM +0800, Qiujun Huang wrote:
> drm_lease_create takes ownership of leases. And leases will be released
> by drm_master_put.
> 
> drm_master_put
>     ->drm_master_destroy
>             ->idr_destroy
> 
> So we needn't call idr_destroy again.
> 
> Reported-and-tested-by: syzbot+05835159fe322770fe3d@...kaller.appspotmail.com
> Signed-off-by: Qiujun Huang <hqjagain@...il.com>

Thanks for the respin, and I've also seen the syzbot confirmation, so all
great.

Merged to -fixes with a cc: stable.
-Daniel

> ---
>  drivers/gpu/drm/drm_lease.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c
> index b481caf..825abe3 100644
> --- a/drivers/gpu/drm/drm_lease.c
> +++ b/drivers/gpu/drm/drm_lease.c
> @@ -542,10 +542,12 @@ int drm_mode_create_lease_ioctl(struct drm_device *dev,
>  	}
>  
>  	DRM_DEBUG_LEASE("Creating lease\n");
> +	/* lessee will take the ownership of leases */
>  	lessee = drm_lease_create(lessor, &leases);
>  
>  	if (IS_ERR(lessee)) {
>  		ret = PTR_ERR(lessee);
> +		idr_destroy(&leases);
>  		goto out_leases;
>  	}
>  
> @@ -580,7 +582,6 @@ int drm_mode_create_lease_ioctl(struct drm_device *dev,
>  
>  out_leases:
>  	put_unused_fd(fd);
> -	idr_destroy(&leases);
>  
>  	DRM_DEBUG_LEASE("drm_mode_create_lease_ioctl failed: %d\n", ret);
>  	return ret;
> -- 
> 1.8.3.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch