From: Rob Clark <rob@xxxxxx>
This simplifies drm fb lifetime, and if the crtc/plane needs to hold
a ref to the fb when disabling a pipe until the next vblank, this
avoids the need to make disabling an overlay synchronous. This is a
problem that shows up when userspace is using a drm plane to
implement a hw cursor.. making overlay disable synchronous causes
a performance problem when x11 is rapidly enabling/disabling the
hw cursor. But not making it synchronous opens up a race condition
for crashing if userspace turns around and immediately deletes the
fb. Refcnt'ing the fb makes it possible to solve this problem.
Signed-off-by: Rob Clark <rob@xxxxxx>
---
drivers/gpu/drm/drm_crtc.c | 38 ++++++++++++++++++++++++++---
drivers/gpu/drm/exynos/exynos_drm_fbdev.c | 4 +--
drivers/gpu/drm/i915/intel_display.c | 4 +--
include/drm/drm_crtc.h | 4 +++
4 files changed, 43 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 08a7aa7..2f928a3 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -294,6 +294,8 @@ int drm_framebuffer_init(struct drm_device *dev, struct drm_framebuffer *fb,
{
int ret;
+ kref_init(&fb->refcount);
+
ret = drm_mode_object_get(dev, &fb->base, DRM_MODE_OBJECT_FB);
if (ret)
return ret;
@@ -307,6 +309,36 @@ int drm_framebuffer_init(struct drm_device *dev, struct drm_framebuffer *fb,
}
EXPORT_SYMBOL(drm_framebuffer_init);
+static void drm_framebuffer_free(struct kref *kref)
+{
+ struct drm_framebuffer *fb =
+ container_of(kref, struct drm_framebuffer, refcount);
+ fb->funcs->destroy(fb);
+}
+
+/**
+ * drm_framebuffer_unreference - unref a framebuffer
+ *
+ * LOCKING:
+ * Caller must hold mode config lock.
+ */
+void drm_framebuffer_unreference(struct drm_framebuffer *fb)
+{
+ struct drm_device *dev = fb->dev;
+ WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
+ kref_put(&fb->refcount, drm_framebuffer_free);
+}
+EXPORT_SYMBOL(drm_framebuffer_unreference);
+
+/**
+ * drm_framebuffer_reference - incr the fb refcnt
+ */
+void drm_framebuffer_reference(struct drm_framebuffer *fb)
+{
+ kref_get(&fb->refcount);
+}
+EXPORT_SYMBOL(drm_framebuffer_reference);
+
/**
* drm_framebuffer_cleanup - remove a framebuffer object
* @fb: framebuffer to remove
@@ -1031,7 +1063,7 @@ void drm_mode_config_cleanup(struct drm_device *dev)
}
list_for_each_entry_safe(fb, fbt, &dev->mode_config.fb_list, head) {
- fb->funcs->destroy(fb);
+ drm_framebuffer_unreference(fb);
}
list_for_each_entry_safe(crtc, ct, &dev->mode_config.crtc_list, head) {
@@ -2339,7 +2371,7 @@ int drm_mode_rmfb(struct drm_device *dev,
/* TODO unhock the destructor from the buffer object */
list_del(&fb->filp_head);
- fb->funcs->destroy(fb);
+ drm_framebuffer_unreference(fb);
out:
mutex_unlock(&dev->mode_config.mutex);
@@ -2490,7 +2522,7 @@ void drm_fb_release(struct drm_file *priv)
mutex_lock(&dev->mode_config.mutex);
list_for_each_entry_safe(fb, tfb, &priv->fbs, filp_head) {
list_del(&fb->filp_head);
- fb->funcs->destroy(fb);
+ drm_framebuffer_unreference(fb);
}
mutex_unlock(&dev->mode_config.mutex);
}
diff --git a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
index d5586cc..05695d6 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
@@ -266,8 +266,8 @@ static void exynos_drm_fbdev_destroy(struct drm_device *dev,
/* release drm framebuffer and real buffer */
if (fb_helper->fb && fb_helper->fb->funcs) {
fb = fb_helper->fb;
- if (fb && fb->funcs->destroy)
- fb->funcs->destroy(fb);
+ if (fb)
+ drm_framebuffer_unreference(fb);
}
/* release linux framebuffer */
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index a8538ac..a9d2328 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5467,7 +5467,7 @@ bool intel_get_load_detect_pipe(struct intel_encoder *intel_encoder,
if (!drm_crtc_helper_set_mode(crtc, mode, 0, 0, old_fb)) {
DRM_DEBUG_KMS("failed to set mode on load-detect pipe\n");
if (old->release_fb)
- old->release_fb->funcs->destroy(old->release_fb);
+ drm_framebuffer_unreference(old->release_fb);
crtc->fb = old_fb;
return false;
}
@@ -5497,7 +5497,7 @@ void intel_release_load_detect_pipe(struct intel_encoder *intel_encoder,
drm_helper_disable_unused_functions(dev);
if (old->release_fb)
- old->release_fb->funcs->destroy(old->release_fb);
+ drm_framebuffer_unreference(old->release_fb);
return;
}
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index bac55c2..8a5b16d 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -221,6 +221,7 @@ struct drm_display_info {
};
struct drm_framebuffer_funcs {
+ /* note: use drm_framebuffer_unreference() */
void (*destroy)(struct drm_framebuffer *framebuffer);
int (*create_handle)(struct drm_framebuffer *fb,
struct drm_file *file_priv,
@@ -245,6 +246,7 @@ struct drm_framebuffer_funcs {
struct drm_framebuffer {
struct drm_device *dev;
+ struct kref refcount;
struct list_head head;
struct drm_mode_object base;
const struct drm_framebuffer_funcs *funcs;
@@ -923,6 +925,8 @@ extern void drm_framebuffer_set_object(struct drm_device *dev,
extern int drm_framebuffer_init(struct drm_device *dev,
struct drm_framebuffer *fb,
const struct drm_framebuffer_funcs *funcs);
+void drm_framebuffer_unreference(struct drm_framebuffer *fb);
+void drm_framebuffer_reference(struct drm_framebuffer *fb);
extern void drm_framebuffer_cleanup(struct drm_framebuffer *fb);
extern int drmfb_probe(struct drm_device *dev, struct drm_crtc *crtc);
extern int drmfb_remove(struct drm_device *dev, struct drm_framebuffer *fb);
--
1.7.9.5
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