On Thu, 07 Oct 2021 13:15:25 +0000 Simon Ser <cont...@emersion.fr> wrote:
> This new IOCTL allows callers to close a framebuffer without > disabling planes or CRTCs. This takes inspiration from Rob Clark's > unref_fb IOCTL [1] and DRM_MODE_FB_PERSIST [2]. > > [1]: > https://lore.kernel.org/dri-devel/20170509153654.23464-1-robdcl...@gmail.com/ > [2]: > https://lore.kernel.org/dri-devel/20211006151921.312714-1-cont...@emersion.fr/ > > Signed-off-by: Simon Ser <cont...@emersion.fr> > Cc: Hans de Goede <hdego...@redhat.com> > Cc: Dennis Filder <d.fil...@web.de> > Cc: Daniel Vetter <dan...@ffwll.ch> > Cc: Pekka Paalanen <ppaala...@gmail.com> > Cc: Rob Clark <robdcl...@gmail.com> > Cc: Sean Paul <seanp...@chromium.org> > --- > drivers/gpu/drm/drm_crtc_internal.h | 2 ++ > drivers/gpu/drm/drm_framebuffer.c | 19 +++++++++++++++++++ > drivers/gpu/drm/drm_ioctl.c | 1 + > include/uapi/drm/drm.h | 19 +++++++++++++++++++ > 4 files changed, 41 insertions(+) ... > diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c > index 8b8744dcf691..545762bc16d0 100644 > --- a/drivers/gpu/drm/drm_ioctl.c > +++ b/drivers/gpu/drm/drm_ioctl.c > @@ -670,6 +670,7 @@ static const struct drm_ioctl_desc drm_ioctls[] = { > DRM_IOCTL_DEF(DRM_IOCTL_MODE_ADDFB, drm_mode_addfb_ioctl, 0), > DRM_IOCTL_DEF(DRM_IOCTL_MODE_ADDFB2, drm_mode_addfb2_ioctl, 0), > DRM_IOCTL_DEF(DRM_IOCTL_MODE_RMFB, drm_mode_rmfb_ioctl, 0), > + DRM_IOCTL_DEF(DRM_IOCTL_MODE_CLOSEFB, drm_mode_closefb_ioctl, 0), > DRM_IOCTL_DEF(DRM_IOCTL_MODE_PAGE_FLIP, drm_mode_page_flip_ioctl, > DRM_MASTER), > DRM_IOCTL_DEF(DRM_IOCTL_MODE_DIRTYFB, drm_mode_dirtyfb_ioctl, > DRM_MASTER), > DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATE_DUMB, drm_mode_create_dumb_ioctl, > 0), > diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h > index 3b810b53ba8b..8726f003f382 100644 > --- a/include/uapi/drm/drm.h > +++ b/include/uapi/drm/drm.h > @@ -1097,6 +1097,25 @@ extern "C" { > #define DRM_IOCTL_SYNCOBJ_TIMELINE_SIGNAL DRM_IOWR(0xCD, struct > drm_syncobj_timeline_array) > > #define DRM_IOCTL_MODE_GETFB2 DRM_IOWR(0xCE, struct > drm_mode_fb_cmd2) > +/** > + * DRM_IOCTL_MODE_CLOSEFB - Close a framebuffer. > + * > + * This closes a framebuffer previously added via ADDFB/ADDFB2. The IOCTL > + * argument is a framebuffer object ID. > + * > + * This IOCTL is similar to &DRM_IOCTL_MODE_RMFB, except it doesn't disable > + * planes and CRTCs. As long as the framebuffer is used by a plane, it's kept > + * alive. When the plane no longer uses the framebuffer (because the > + * framebuffer is replaced with another one, or the plane is disabled), the > + * framebuffer is cleaned up. > + * > + * This is useful to implement flicker-free transitions between two > processes. > + * > + * Depending on the threat model, user-space may want to ensure that the > + * framebuffer doesn't expose any sensitive user information: closed > + * framebuffers attached to a plane can be read back by the next DRM master. > + */ LGTM! Semantics Acked-by: Pekka Paalanen <pekka.paala...@collabora.com> > +#define DRM_IOCTL_MODE_CLOSEFB DRM_IOWR(0xCF, unsigned int) Should it have a structure with 'flags' for future-proofing? ISTR some rule of thumb that everything new must have 'flags' field enforced to be zero just in case. I only now saw that RMFB cannot have flags. Thanks, pq > > /* > * Device specific ioctls should only be in their respective headers
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