If struct fb_ops is defined in a library like cma, fb_open() takes a
ref on the library instead of the driver module. Use
fb_ops.fb_open/fb_release to ensure that the driver module is pinned.
Add drm_fb_helper_fb_open() and drm_fb_helper_fb_release() to
DRM_FB_HELPER_DEFAULT_OPS().
Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx>
---
drivers/gpu/drm/drm_fb_helper.c | 41 +++++++++++++++++++++++++++++++++++++++++
include/drm/drm_fb_helper.h | 14 ++++++++++++++
2 files changed, 55 insertions(+)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 74c1053..b080004 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1037,6 +1037,47 @@ void drm_fb_helper_fb_destroy(struct fb_info *info)
EXPORT_SYMBOL(drm_fb_helper_fb_destroy);
/**
+ * drm_fb_helper_fb_open - implementation for &fb_ops.fb_open
+ * @info: fbdev registered by the helper
+ * @user: 1=userspace, 0=fbcon
+ *
+ * If &fb_ops is wrapped in a library, pin the driver module.
+ */
+int drm_fb_helper_fb_open(struct fb_info *info, int user)
+{
+ struct drm_fb_helper *fb_helper = info->par;
+ struct drm_device *dev = fb_helper->dev;
+
+ /* Skip fbcon, it detaches itself in unregister_framebuffer() */
+ if (user && info->fbops->owner != dev->driver->fops->owner) {
+ if (!try_module_get(dev->driver->fops->owner))
+ return -ENODEV;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_fb_open);
+
+/**
+ * drm_fb_helper_fb_release - implementation for &fb_ops.fb_release
+ * @info: fbdev registered by the helper
+ * @user: 1=userspace, 0=fbcon
+ *
+ * If &fb_ops is wrapped in a library, unpin the driver module.
+ */
+int drm_fb_helper_fb_release(struct fb_info *info, int user)
+{
+ struct drm_fb_helper *fb_helper = info->par;
+ struct drm_device *dev = fb_helper->dev;
+
+ if (user && info->fbops->owner != dev->driver->fops->owner)
+ module_put(dev->driver->fops->owner);
+
+ return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_fb_release);
+
+/**
* drm_fb_helper_sys_read - wrapper around fb_sys_read
* @info: fb_info struct pointer
* @buf: userspace buffer to read from framebuffer memory
diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index dd78eb3..b44fc62 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -233,6 +233,8 @@ struct drm_fb_helper {
*/
#define DRM_FB_HELPER_DEFAULT_OPS \
.fb_destroy = drm_fb_helper_fb_destroy, \
+ .fb_open = drm_fb_helper_fb_open, \
+ .fb_release = drm_fb_helper_fb_release, \
.fb_check_var = drm_fb_helper_check_var, \
.fb_set_par = drm_fb_helper_set_par, \
.fb_setcmap = drm_fb_helper_setcmap, \
@@ -270,6 +272,8 @@ void drm_fb_helper_deferred_io(struct fb_info *info,
struct list_head *pagelist);
void drm_fb_helper_fb_destroy(struct fb_info *info);
+int drm_fb_helper_fb_open(struct fb_info *info, int user);
+int drm_fb_helper_fb_release(struct fb_info *info, int user);
ssize_t drm_fb_helper_sys_read(struct fb_info *info, char __user *buf,
size_t count, loff_t *ppos);
@@ -405,6 +409,16 @@ static inline void drm_fb_helper_fb_destroy(struct fb_info *info)
{
}
+static inline int drm_fb_helper_fb_open(struct fb_info *info, int user)
+{
+ return -ENODEV;
+}
+
+static inline int drm_fb_helper_fb_release(struct fb_info *info, int user)
+{
+ return -ENODEV;
+}
+
static inline ssize_t drm_fb_helper_sys_read(struct fb_info *info,
char __user *buf, size_t count,
loff_t *ppos)
--
2.7.4
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