diff options
| author |   John Bates <jbates@chromium.org> | 2020-02-20 14:53:19 -0800 |
|---|---|---|
| committer |   Gerd Hoffmann <kraxel@redhat.com> | 2020-02-24 15:45:34 +0100 |
| commit | fbb30168c7395b9cfeb9e6f7b0c0bca854a6552d (patch) | |
| tree | cf8c61d6b684676f6812793271ffaa09ddee15a8 /drivers/gpu | |
| parent | drm/panfrost: perfcnt: Reserve/use the AS attached to the perfcnt MMU context (diff) | |
| download | linux-dev-fbb30168c7395b9cfeb9e6f7b0c0bca854a6552d.tar.xz linux-dev-fbb30168c7395b9cfeb9e6f7b0c0bca854a6552d.zip | |
drm/virtio: fix resource id creation race
The previous code was not thread safe and caused
undefined behavior from spurious duplicate resource IDs.
In this patch, an atomic_t is used instead. We no longer
see any duplicate IDs in tests with this change.
Fixes: 16065fcdd19d ("drm/virtio: do NOT reuse resource ids")
Signed-off-by: John Bates <jbates@chromium.org>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200220225319.45621-1-jbates@chromium.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/virtio/virtgpu_object.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c index 017a9e0fc3bb..890121a45625 100644 --- a/drivers/gpu/drm/virtio/virtgpu_object.c +++ b/drivers/gpu/drm/virtio/virtgpu_object.c @@ -42,8 +42,8 @@ static int virtio_gpu_resource_id_get(struct virtio_gpu_device *vgdev, * "f91a9dd35715 Fix unlinking resources from hash * table." (Feb 2019) fixes the bug. */ - static int handle; - handle++; + static atomic_t seqno = ATOMIC_INIT(0); + int handle = atomic_inc_return(&seqno); *resid = handle + 1; } else { int handle = ida_alloc(&vgdev->resource_ida, GFP_KERNEL); |