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SubjectRe: [PATCH] drm/lease: fix WARNING in idr_destroy
On Mon, Mar 16, 2020 at 11:36:08AM +0800, Qiujun Huang wrote:
> leases has been destroyed:
> drm_master_put
> ->drm_master_destroy
> ->idr_destroy
>
> so the "out_lessee" needn't to call idr_destroy again.
>
> Reported-and-tested-by: syzbot+05835159fe322770fe3d@syzkaller.appspotmail.com
> Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
> ---
> drivers/gpu/drm/drm_lease.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c
> index b481caf..54506c2 100644
> --- a/drivers/gpu/drm/drm_lease.c
> +++ b/drivers/gpu/drm/drm_lease.c
> @@ -577,11 +577,14 @@ int drm_mode_create_lease_ioctl(struct drm_device *dev,
>
> out_lessee:
> drm_master_put(&lessee);
> + goto err_exit;

I think this is correct, but also confusioning and inconsistent with the
existing style. Most error cases before drm_lease_create explicit destroy
the idr, except the one for drm_lease_create.

Instead of your patch I'd
- remove the idr_destry from the error unrolling here
- add it the to drm_lease_create error case
- add a comment above the call to drm_lease_crete that it takes ownership
of the lease idr

Can you pls respin and retest to make sure that patch is still correct?

Thanks, Daniel

>
> out_leases:
> - put_unused_fd(fd);
> idr_destroy(&leases);
>
> +err_exit:
> + put_unused_fd(fd);
> +
> 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

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