drm_mode_rmfb performs two operations: drop the FB from the file_priv->fbs list, and make sure the FB is no longer used on a plane.
In the next commit an IOCTL which only does so former will be introduced, so let's split it into a separate function.
No functional change, only refactoring.
Signed-off-by: Simon Ser contact@emersion.fr Cc: Hans de Goede hdegoede@redhat.com Cc: Dennis Filder d.filder@web.de Cc: Daniel Vetter daniel@ffwll.ch Cc: Pekka Paalanen ppaalanen@gmail.com Cc: Rob Clark robdclark@gmail.com Cc: Sean Paul seanpaul@chromium.org --- drivers/gpu/drm/drm_framebuffer.c | 51 +++++++++++++++++++------------ 1 file changed, 31 insertions(+), 20 deletions(-)
diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c index 07f5abc875e9..2352972ba6ac 100644 --- a/drivers/gpu/drm/drm_framebuffer.c +++ b/drivers/gpu/drm/drm_framebuffer.c @@ -412,6 +412,31 @@ static void drm_mode_rmfb_work_fn(struct work_struct *w) } }
+static int drm_mode_closefb(struct drm_framebuffer *fb, + struct drm_file *file_priv) +{ + struct drm_framebuffer *fbl = NULL; + bool found = false; + + mutex_lock(&file_priv->fbs_lock); + list_for_each_entry(fbl, &file_priv->fbs, filp_head) + if (fb == fbl) + found = true; + + if (!found) { + mutex_unlock(&file_priv->fbs_lock); + return -ENOENT; + } + + list_del_init(&fb->filp_head); + mutex_unlock(&file_priv->fbs_lock); + + /* Drop the reference that was stored in the fbs list */ + drm_framebuffer_put(fb); + + return 0; +} + /** * drm_mode_rmfb - remove an FB from the configuration * @dev: drm device @@ -429,8 +454,7 @@ int drm_mode_rmfb(struct drm_device *dev, u32 fb_id, struct drm_file *file_priv) { struct drm_framebuffer *fb = NULL; - struct drm_framebuffer *fbl = NULL; - int found = 0; + int ret;
if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EOPNOTSUPP; @@ -439,23 +463,14 @@ int drm_mode_rmfb(struct drm_device *dev, u32 fb_id, if (!fb) return -ENOENT;
- mutex_lock(&file_priv->fbs_lock); - list_for_each_entry(fbl, &file_priv->fbs, filp_head) - if (fb == fbl) - found = 1; - if (!found) { - mutex_unlock(&file_priv->fbs_lock); - goto fail_unref; + ret = drm_mode_closefb(fb, file_priv); + if (ret != 0) { + drm_framebuffer_put(fb); + return ret; }
- list_del_init(&fb->filp_head); - mutex_unlock(&file_priv->fbs_lock); - - /* drop the reference we picked up in framebuffer lookup */ - drm_framebuffer_put(fb); - /* - * we now own the reference that was stored in the fbs list + * We now own the reference we picked up in drm_framebuffer_lookup. * * drm_framebuffer_remove may fail with -EINTR on pending signals, * so run this in a separate stack as there's no way to correctly @@ -475,10 +490,6 @@ int drm_mode_rmfb(struct drm_device *dev, u32 fb_id, drm_framebuffer_put(fb);
return 0; - -fail_unref: - drm_framebuffer_put(fb); - return -ENOENT; }
int drm_mode_rmfb_ioctl(struct drm_device *dev,
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-robdclark@gmail.com... [2]: https://lore.kernel.org/dri-devel/20211006151921.312714-1-contact@emersion.f...
Signed-off-by: Simon Ser contact@emersion.fr Cc: Hans de Goede hdegoede@redhat.com Cc: Dennis Filder d.filder@web.de Cc: Daniel Vetter daniel@ffwll.ch Cc: Pekka Paalanen ppaalanen@gmail.com Cc: Rob Clark robdclark@gmail.com Cc: Sean Paul seanpaul@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_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h index 63279e984342..c6377b9ba981 100644 --- a/drivers/gpu/drm/drm_crtc_internal.h +++ b/drivers/gpu/drm/drm_crtc_internal.h @@ -221,6 +221,8 @@ int drm_mode_addfb2_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv); int drm_mode_rmfb_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv); +int drm_mode_closefb_ioctl(struct drm_device *dev, + void *data, struct drm_file *file_priv); int drm_mode_getfb(struct drm_device *dev, void *data, struct drm_file *file_priv); int drm_mode_getfb2_ioctl(struct drm_device *dev, diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c index 2352972ba6ac..15f7c22dbd4a 100644 --- a/drivers/gpu/drm/drm_framebuffer.c +++ b/drivers/gpu/drm/drm_framebuffer.c @@ -500,6 +500,25 @@ int drm_mode_rmfb_ioctl(struct drm_device *dev, return drm_mode_rmfb(dev, *fb_id, file_priv); }
+int drm_mode_closefb_ioctl(struct drm_device *dev, + void *data, struct drm_file *file_priv) +{ + uint32_t *fb_id = data; + struct drm_framebuffer *fb; + int ret; + + if (!drm_core_check_feature(dev, DRIVER_MODESET)) + return -EOPNOTSUPP; + + fb = drm_framebuffer_lookup(dev, file_priv, *fb_id); + if (!fb) + return -ENOENT; + + ret = drm_mode_closefb(fb, file_priv); + drm_framebuffer_put(fb); + return ret; +} + /** * drm_mode_getfb - get FB info * @dev: drm device for the ioctl 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. + */ +#define DRM_IOCTL_MODE_CLOSEFB DRM_IOWR(0xCF, unsigned int)
/* * Device specific ioctls should only be in their respective headers
On Thu, 07 Oct 2021 13:15:25 +0000 Simon Ser contact@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].
Signed-off-by: Simon Ser contact@emersion.fr Cc: Hans de Goede hdegoede@redhat.com Cc: Dennis Filder d.filder@web.de Cc: Daniel Vetter daniel@ffwll.ch Cc: Pekka Paalanen ppaalanen@gmail.com Cc: Rob Clark robdclark@gmail.com Cc: Sean Paul seanpaul@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.paalanen@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
Thanks for having a look at this patch, Pekka!
On Friday, October 8th, 2021 at 09:29, Pekka Paalanen ppaalanen@gmail.com wrote:
+#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.
I wonder. I don't mind adding a struct with flags or padding, not sure what the policy is for the DRM subsystem.
dri-devel@lists.freedesktop.org
-
Pekka Paalanen -
Simon Ser