Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964874AbaFSSxB (ORCPT ); Thu, 19 Jun 2014 14:53:01 -0400 Received: from mail-ig0-f179.google.com ([209.85.213.179]:34744 "EHLO mail-ig0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933059AbaFSSw5 (ORCPT ); Thu, 19 Jun 2014 14:52:57 -0400 MIME-Version: 1.0 In-Reply-To: <20140619181918.GA24155@kroah.com> 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 14:52:56 -0400 Message-ID: Subject: Re: [REPOST PATCH 1/8] fence: dma-buf cross-device synchronization (v17) From: Rob Clark To: Greg KH Cc: Maarten Lankhorst , linux-arch@vger.kernel.org, Thomas Hellstrom , Linux Kernel Mailing List , "dri-devel@lists.freedesktop.org" , "linaro-mm-sig@lists.linaro.org" , Thierry Reding , Colin Cross , Daniel Vetter , Sumit Semwal , "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 2:19 PM, 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? :) Well, all I know is what happened with dmabuf. This seems like the exact same scenario (same vendor, same driver, same use-case). Not really sure how we could completely prevent indirect usage, given that drm core and many of the drivers are dual MIT/GPL. (But ofc, IANAL.) > 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? In the general case, I would agree. But in this specific case, I am not very optimistic. That said, it isn't really my loss if it is _GPL().. I don't have to use or support that particular driver. But given that we have some history from the same debate with dma-buf, I think it is pretty easy to infer the result from making fence EXPORT_SYMBOL_GPL(). BR, -R > thanks, > > greg k-h -- 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/