On 5/16/25 21:33, David Francis wrote:
> CRIU restore of drm buffer objects requires the ability to create
> or import a buffer object with a specific gem handle.
>
> Add new drm ioctl DRM_IOCTL_PRIME_CHANGE_GEM_HANDLE, which takes
> the gem handle of an object and moves that object to a
> specified new gem handle.
>
> This ioctl needs to call drm_prime_remove_buf_handle,
> but that function acquires the prime lock, which the ioctl
> needs to hold for other purposes.
>
> Make drm_prime_remove_buf_handle not acquire the prime lock,
> and change its other caller to reflect this.
>
> Signed-off-by: David Francis <david.fran...@amd.com>
First of all you need to add more people and the dri-devel mailing list for
review.
A few more comments below.
> ---
> drivers/gpu/drm/drm_gem.c | 5 ++++
> drivers/gpu/drm/drm_internal.h | 2 ++
> drivers/gpu/drm/drm_ioctl.c | 1 +
> drivers/gpu/drm/drm_prime.c | 43 ++++++++++++++++++++++++++++++----
> include/uapi/drm/drm.h | 7 ++++++
> 5 files changed, 54 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> index ee811764c3df..f56eeed808d2 100644
> --- a/drivers/gpu/drm/drm_gem.c
> +++ b/drivers/gpu/drm/drm_gem.c
> @@ -282,7 +282,12 @@ drm_gem_object_release_handle(int id, void *ptr, void
> *data)
> if (obj->funcs->close)
> obj->funcs->close(obj, file_priv);
>
> + mutex_lock(&file_priv->prime.lock);
> +
> drm_prime_remove_buf_handle(&file_priv->prime, id);
> +
> + mutex_unlock(&file_priv->prime.lock);
> +
> drm_vma_node_revoke(&obj->vma_node, file_priv);
>
> drm_gem_object_handle_put_unlocked(obj);
> diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
> index b2b6a8e49dda..7437e5eaf8db 100644
> --- a/drivers/gpu/drm/drm_internal.h
> +++ b/drivers/gpu/drm/drm_internal.h
> @@ -82,6 +82,8 @@ int drm_prime_handle_to_fd_ioctl(struct drm_device *dev,
> void *data,
> struct drm_file *file_priv);
> int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
> struct drm_file *file_priv);
> +int drm_prime_change_gem_handle_ioctl(struct drm_device *dev, void *data,
> + struct drm_file *file_priv);
>
> void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv);
> void drm_prime_destroy_file_private(struct drm_prime_file_private
> *prime_fpriv);
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index f593dc569d31..f9b531311aac 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -658,6 +658,7 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
>
> DRM_IOCTL_DEF(DRM_IOCTL_PRIME_HANDLE_TO_FD,
> drm_prime_handle_to_fd_ioctl, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF(DRM_IOCTL_PRIME_FD_TO_HANDLE,
> drm_prime_fd_to_handle_ioctl, DRM_RENDER_ALLOW),
> + DRM_IOCTL_DEF(DRM_IOCTL_PRIME_CHANGE_GEM_HANDLE,
> drm_prime_change_gem_handle_ioctl, DRM_RENDER_ALLOW),
>
> DRM_IOCTL_DEF(DRM_IOCTL_SET_CLIENT_NAME, drm_set_client_name,
> DRM_RENDER_ALLOW),
>
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index 0e3f8adf162f..8f3317fcae49 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -190,8 +190,6 @@ void drm_prime_remove_buf_handle(struct
> drm_prime_file_private *prime_fpriv,
> {
> struct rb_node *rb;
>
> - mutex_lock(&prime_fpriv->lock);
> -
> rb = prime_fpriv->handles.rb_node;
> while (rb) {
> struct drm_prime_member *member;
> @@ -210,8 +208,6 @@ void drm_prime_remove_buf_handle(struct
> drm_prime_file_private *prime_fpriv,
> rb = rb->rb_left;
> }
> }
> -
> - mutex_unlock(&prime_fpriv->lock);
> }
>
> void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
> @@ -1084,3 +1080,42 @@ void drm_prime_gem_destroy(struct drm_gem_object *obj,
> struct sg_table *sg)
> dma_buf_put(dma_buf);
> }
> EXPORT_SYMBOL(drm_prime_gem_destroy);
> +
> +int drm_prime_change_gem_handle_ioctl(struct drm_device *dev, void *data,
> + struct drm_file *file_priv)
This is not a prime function, but rather a GEM function. So the new code should
go into drm_gem.c, I suggest close to the drm_gem_open_ioctl() function.
> +{
> + struct drm_prime_change_gem_handle *args = data;
> + struct drm_gem_object *obj;
> + int ret;
> +
> + obj = drm_gem_object_lookup(file_priv, args->handle);
> +
> + if (!obj)
> + return -ENOENT;
> +
> + get_dma_buf(obj->dma_buf);
> +
> + mutex_lock(&file_priv->prime.lock);
> +
> + drm_prime_remove_buf_handle(&file_priv->prime, args->handle);
> +
> + spin_lock(&file_priv->table_lock);
> +
> + idr_remove(&file_priv->object_idr, args->handle);
> + ret = idr_alloc(&file_priv->object_idr, obj, args->new_handle,
> args->new_handle + 1, GFP_NOWAIT);
This needs to be reordered.
First call idr_alloc() to check if the new handle is actually available.
Then call drm_prime_add_buf_handle() when the GEM object actually has a DMA-buf
associated with it.
When that worked call drm_prime_remove_buf_handle() and finally idr_remove().
Regards,
Christian.
> +
> + spin_unlock(&file_priv->table_lock);
> +
> + if (ret < 0)
> + goto out_unlock;
> +
> + ret = drm_prime_add_buf_handle(&file_priv->prime, obj->dma_buf,
> args->new_handle);
> + if (ret < 0)
> + goto out_unlock;
> +
> +out_unlock:
> + mutex_unlock(&file_priv->prime.lock);
> + dma_buf_put(obj->dma_buf);
> +
> + return ret;
> +}
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index 7fba37b94401..ae701b8f9314 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -625,6 +625,11 @@ struct drm_gem_open {
> __u64 size;
> };
>
> +struct drm_prime_change_gem_handle {
> + __u32 handle;
> + __u32 new_handle;
> +};
> +
> /**
> * DRM_CAP_DUMB_BUFFER
> *
> @@ -1305,6 +1310,8 @@ extern "C" {
> */
> #define DRM_IOCTL_SET_CLIENT_NAME DRM_IOWR(0xD1, struct
> drm_set_client_name)
>
> +#define DRM_IOCTL_PRIME_CHANGE_GEM_HANDLE DRM_IOWR(0xD2, struct
> drm_prime_change_gem_handle)
> +
> /*
> * Device specific ioctls should only be in their respective headers
> * The device specific ioctl range is from 0x40 to 0x9f.
