Hi Laurent, On Sat, Nov 29, 2014 at 6:11 PM, Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > 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 ? > I have just compile tested it. > Should I take it in my tree or will you send a pull request for the whole > series ? > Probably you can pick this up via your tree. Thanks, --Prabhakar Lad >> >> 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
