Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966197AbaFSXVf (ORCPT ); Thu, 19 Jun 2014 19:21:35 -0400 Received: from mail-ig0-f169.google.com ([209.85.213.169]:55096 "EHLO mail-ig0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965467AbaFSXVd (ORCPT ); Thu, 19 Jun 2014 19:21:33 -0400 MIME-Version: 1.0 In-Reply-To: References: <20140618102957.15728.43525.stgit@patser> <20140618103653.15728.4942.stgit@patser> <20140619011327.GC10921@kroah.com> <20140619170059.GA1224@kroah.com> <20140619181918.GA24155@kroah.com> Date: Thu, 19 Jun 2014 19:21:32 -0400 Message-ID: Subject: Re: [REPOST PATCH 1/8] fence: dma-buf cross-device synchronization (v17) From: Rob Clark To: Dave Airlie Cc: Greg KH , linux-arch@vger.kernel.org, Thomas Hellstrom , Linux Kernel Mailing List , "dri-devel@lists.freedesktop.org" , "linaro-mm-sig@lists.linaro.org" , Colin Cross , "linux-media@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 19, 2014 at 5:50 PM, Dave Airlie wrote: > On 20 June 2014 04:19, Greg KH wrote: >> On Thu, Jun 19, 2014 at 01:45:30PM -0400, Rob Clark wrote: >>> On Thu, Jun 19, 2014 at 1:00 PM, Greg KH wrote: >>> > On Thu, Jun 19, 2014 at 10:00:18AM -0400, Rob Clark wrote: >>> >> On Wed, Jun 18, 2014 at 9:13 PM, Greg KH wrote: >>> >> > On Wed, Jun 18, 2014 at 12:36:54PM +0200, Maarten Lankhorst wrote: >>> >> >> +#define CREATE_TRACE_POINTS >>> >> >> +#include >>> >> >> + >>> >> >> +EXPORT_TRACEPOINT_SYMBOL(fence_annotate_wait_on); >>> >> >> +EXPORT_TRACEPOINT_SYMBOL(fence_emit); >>> >> > >>> >> > Are you really willing to live with these as tracepoints for forever? >>> >> > What is the use of them in debugging? Was it just for debugging the >>> >> > fence code, or for something else? >>> >> > >>> >> >> +/** >>> >> >> + * fence_context_alloc - allocate an array of fence contexts >>> >> >> + * @num: [in] amount of contexts to allocate >>> >> >> + * >>> >> >> + * This function will return the first index of the number of fences allocated. >>> >> >> + * The fence context is used for setting fence->context to a unique number. >>> >> >> + */ >>> >> >> +unsigned fence_context_alloc(unsigned num) >>> >> >> +{ >>> >> >> + BUG_ON(!num); >>> >> >> + return atomic_add_return(num, &fence_context_counter) - num; >>> >> >> +} >>> >> >> +EXPORT_SYMBOL(fence_context_alloc); >>> >> > >>> >> > EXPORT_SYMBOL_GPL()? Same goes for all of the exports in here. >>> >> > Traditionally all of the driver core exports have been with this >>> >> > marking, any objection to making that change here as well? >>> >> >>> >> tbh, I prefer EXPORT_SYMBOL().. well, I'd prefer even more if there >>> >> wasn't even a need for EXPORT_SYMBOL_GPL(), but sadly it is a fact of >>> >> life. We already went through this debate once with dma-buf. We >>> >> aren't going to change $evil_vendor's mind about non-gpl modules. The >>> >> only result will be a more flugly convoluted solution (ie. use syncpt >>> >> EXPORT_SYMBOL() on top of fence EXPORT_SYMBOL_GPL()) just as a >>> >> workaround, with the result that no-one benefits. >>> > >>> > It has been proven that using _GPL() exports have caused companies to >>> > release their code "properly" over the years, so as these really are >>> > Linux-only apis, please change them to be marked this way, it helps >>> > everyone out in the end. >>> >>> Well, maybe that is the true in some cases. But it certainly didn't >>> work out that way for dma-buf. And I think the end result is worse. >>> >>> I don't really like coming down on the side of EXPORT_SYMBOL() instead >>> of EXPORT_SYMBOL_GPL(), but if we do use EXPORT_SYMBOL_GPL() then the >>> result will only be creative workarounds using the _GPL symbols >>> indirectly by whatever is available via EXPORT_SYMBOL(). I don't >>> really see how that will be better. >> >> You are saying that you _know_ companies will violate our license, so >> you should just "give up"? And how do you know people aren't working on >> preventing those "indirect" usages as well? :) >> >> Sorry, I'm not going to give up here, again, it has proven to work in >> the past in changing the ways of _very_ large companies, why stop now? > > I've found large companies shipping lots of hw putting pressure on > other large/small companies seems to be only way this has ever > happened, we'd like to cover that up and say its some great GPL > enforcement thing. > > To be honest, author's choice is how I'd treat this. > > Personally I think _GPL is broken by design, and that Linus's initial > point for them has been so diluted by random lobby groups asking for > every symbol to be _GPL that they are becoming effectively pointless > now. I also dislike the fact that the lobby groups don't just bring > violators to court. I'm also sure someone like the LF could have a > nice income stream if Linus gave them permission to enforce his > copyrights. > > But anyways, has someone checked that iOS or Windows don't have a > fence interface? so we know that this is a Linux only interface and > any works using it are derived? Say the nvidia driver isn't a derived > work now, will using this interface magically translate it into a > derived work, so we can go sue them? I don't think so. I've no ideas about what the APIs are in windows, but windows has had multi-gpu support for a *long* time, which implies some mechanism like dmabuf and fence.. this isn't exactly an area where we are trailblazing here. BR, -R > But its up to Maarten and Rob, and if they say no _GPL then I don't > think we should be overriding authors intents. > > Dave. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/