Hi folks, I've been working on this for some time now but only got the full patchset working some moments ago. The patchset properly, I believe, fixes the issue of removing a device whilst streaming.
Media device is refcounted and its memory is only released once the last reference is gone: unregistering is simply unregistering, it no longer should release memory which could be further accessed. A video node or a sub-device node also gets a reference to the media device, i.e. the release function of the video device node will release its reference to the media device. The same goes for file handles to the media device. As a side effect of refcounting the media device, it is allocate together with the media devnode. The driver may also rely its own resources to the media device. Alternatively there's also a priv field to hold drivers private pointer (for container_of() is an option in this case). I've tested this by manually unbinding the omap3isp platform device while streaming. Driver changes are required for this to work; by not using dynamic allocation (i.e. media_device_alloc()) the old behaviour is still supported. This is still unlikely to be a grave problem as there are not that many device drivers that support physically removable devices. We've had this problem for other devices for many years without paying much notice --- that doesn't mean I don't think at least drivers for removable devices shouldn't be changed as part of the set later on, I'd just like to get review comments on the approach first. The three patches that originally partially resolved some of these issues are reverted in the beginning of the set. I'm still posting this as an RFC mainly since the testing is somewhat limited so far. -- Kind regards, Sakari -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
