Hello,
first of all: thanks for your patch and sorry for being late with my review question.
On Fri, Jun 18, 2021 at 7:28 AM Jiajun Cao jjcao20@fudan.edu.cn wrote:
Fix a potential NULL pointer exception when meson_drv_unbind() attempts to operate on the driver_data priv which may be NULL. Add a null pointer check on the priv struct to avoid the NULL pointer dereference after calling dev_get_drvdata(), just like the null pointer checks done on the struct priv in the function meson_drv_shutdown(), meson_drv_pm_suspend() and meson_drv_pm_resume().
I am trying to review Amlogic Meson related patches in the DRM subsystem so I can help Neil with this. However, I am still new to this so please help me educate on this topic.
[...]
static void meson_drv_unbind(struct device *dev) { struct meson_drm *priv = dev_get_drvdata(dev);
struct drm_device *drm = priv->drm;
struct drm_device *drm;if (!priv)return;
My understanding of the component framework is that meson_drv_unbind() is only called if previously meson_drv_bind() was called (and did not return any error). This is different from meson_drv_shutdown() (for example) because that can be called if meson_drv_probe() returns 0 (success) in case the "count" variable was 0 (then the probe function does nothing).
As I mentioned before: I am still learning about the DRM subsystem in the Linux kernel. So it would be great if you could help me understand for which scenarios this newly added if-condition is needed.
Thank you! Best regards, Martin