Hi Prabhakar, On Friday 28 November 2014 17:06:52 Prabhakar Lad wrote: > On Thu, Nov 27, 2014 at 9:32 PM, Laurent Pinchart wrote: > > Hi Prabhakar, > > [Snip] > > >> + queue->queue.lock = &queue->mutex; > > > > I'm a bit concerned that this would introduce future breakages. Setting > > the queue.lock pointer enables locking in all vb2_fop_* and vb2_ops_wait_* > > functions. The uvcvideo driver isn't ready for that, but doesn't use the > > vb2_fop_* functions yet, so that's not an issue. However, in the future, > > videobuf2 might use the lock in more places, including functions used by > > the uvcvideo driver. This could then cause breakages. > > Even if in future if videobuf2 uses this lock it would be in helpers mostly, > so any way it doesn’t harm :) My concern is about vb2 starting using the lock in existing helpers used by the uvcvideo driver. I suppose we can deal with it later. > > It would be better to completely convert the uvcvideo driver to the > > vb2_fop_* functions if we want to use vb2_ops_*. I'm not sure how complex > > that would be though, and whether it would be possible while still > > keeping the fine-grained locking implemented by the uvcvideo driver. Do > > you think it should be attempted ? > > mmap & poll should be fairly simple, looks like open & release cannot be > dropped as it does some usb_autopm_get/put_interface() calls which I am not > aware of. I've looked at that, and there's a race condition in vb2_fop_poll() (for which I've already sent a patch) and possible in vb2_mmap() (raised the issue on #v4l today) as well that need to be fixed first. Anyway, for this patch Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> Have you tested it by the way ? Should I take it in my tree or will you send a pull request for the whole series ? > >> ret = vb2_queue_init(&queue->queue); > >> if (ret) > >> return ret; -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
