On Thu, 16 Feb 2023 20:48:05 +0100 Daniel Vetter <daniel@xxxxxxxx> wrote: > On Thu, Feb 16, 2023 at 01:09:45PM +0000, Simon Ser wrote: > > This is a bit tricky, because of the ref'counting considerations. > > See also [1] for more discussion about this topic. Since this is > > kernel docs, I've decided to elaborate a bit less on the user-space > > details. > > > > [1]: https://gitlab.freedesktop.org/mesa/drm/-/merge_requests/110 > > > > Signed-off-by: Simon Ser <contact@xxxxxxxxxxx> > > Cc: Daniel Vetter <daniel@xxxxxxxx> > > Cc: Pekka Paalanen <ppaalanen@xxxxxxxxx> > > Cc: Daniel Stone <daniel@xxxxxxxxxxxxx> > > --- > > include/uapi/drm/drm.h | 13 +++++++++++++ > > 1 file changed, 13 insertions(+) > > > > diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h > > index 54b2313c8332..4829f1fa9570 100644 > > --- a/include/uapi/drm/drm.h > > +++ b/include/uapi/drm/drm.h > > @@ -972,6 +972,19 @@ extern "C" { > > #define DRM_IOCTL_GET_STATS DRM_IOR( 0x06, struct drm_stats) > > #define DRM_IOCTL_SET_VERSION DRM_IOWR(0x07, struct drm_set_version) > > #define DRM_IOCTL_MODESET_CTL DRM_IOW(0x08, struct drm_modeset_ctl) > > +/** > > + * DRM_IOCTL_GEM_CLOSE - Close a GEM handle. > > + * > > + * GEM handles are not reference-counted by the kernel. User-space is > > + * responsible for managing their lifetime. For example, if user-space imports > > + * the same memory object twice on the same DRM file description, the same GEM > > + * handle is returned by both imports, and user-space needs to ensure > > + * &DRM_IOCTL_GEM_CLOSE is performed once only. The same situation can happen > > + * when a memory object is allocated, then exported and imported again on the > > + * same DRM file description. The &DRM_IOCTL_MODE_GETFB2 IOCTL is an exception > > + * and always returns fresh new GEM handles even if an existing GEM handle > > + * already refers to the same memory object before the IOCTL is performed. > > I'd duplicate the relevant parts into each ioctl doc too, just to increase > the chances people notice these caveats. But that's stuf for these other > patches. for this one: > > Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > > btw do the links from on ioctl text to the other work? > -Daniel This one Acked-by: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxx> I agree with Daniel's comments to both patches, and nothing else came to my mind. Thanks, pq > > > + */ > > #define DRM_IOCTL_GEM_CLOSE DRM_IOW (0x09, struct drm_gem_close) > > #define DRM_IOCTL_GEM_FLINK DRM_IOWR(0x0a, struct drm_gem_flink) > > #define DRM_IOCTL_GEM_OPEN DRM_IOWR(0x0b, struct drm_gem_open) > > -- > > 2.39.1 > > > > >
Attachment:
pgpIjHEA_BB_K.pgp
Description: OpenPGP digital signature
