Date:   Mon, 13 Feb 2023 19:06:11 +0200
From:   Leon Romanovsky <leon@kernel.org>
To:     Nick Alcock <nick.alcock@oracle.com>
Cc:     Conor Dooley <conor@kernel.org>, mcgrof@kernel.org,
        linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-pci@vger.kernel.org, linux-riscv@lists.infradead.org
Subject: Re: [PATCH 8/8] kbuild, PCI: microchip: comment out MODULE_LICENSE
 in non-modules
Message-ID: <Y+puA2V5BoH/Cbr2@unreal>
References: <20230210164749.368998-1-nick.alcock@oracle.com>
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On Mon, Feb 13, 2023 at 04:13:00PM +0000, Nick Alcock wrote:
> [Modified resend: my MTA claimed not to send it but then sent it to some
>  recipients anyway, and then I was asked not to do some of the things
>  I'd offered after I sent it.]
> 
> On 12 Feb 2023, Leon Romanovsky told this:
> 
> > On Fri, Feb 10, 2023 at 08:10:43PM +0000, Conor Dooley wrote:
> >> On Fri, Feb 10, 2023 at 07:26:38PM +0000, Nick Alcock wrote:
> >> > On 10 Feb 2023, Conor Dooley said:
> >> > > FYI $subject seems wrong, this is a PCI patch AFAICT.
> >
> > <...>
> >
> >> > kbuild is present in every patch in the series because this is a
> >> > kbuild-driven change (the thing it disturbs is part of the build system,
> >> > the construction of modules.builtin*). This seems to be common practice
> >> > for kbuild-related treewide changes.
> >> 
> >> Okay, I'll take your word for it. It just looked/looks odd to me!
> >
> > It looks odd to me too. Please add SPDX tag in modules which don't have
> > it already, instead of commenting code.
> 
> Alas... nearly all of them *do* have it already, and in most cases it is
> different. Usually not *very* different, but different. In most cases it
> is more specific, e.g. drivers/soc/fujitsu/a64fx-diag.c, where we have
> MODULE_LICENSE("GPL") but SPDX says it's GPL-2.0-only, but then there
> are things like lib/packing.c, which throughout its history in the tree
> has combined // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
> and MODULE_LICENSE("GPL v2"); which are just not the same thing.
> 
> I commented the MODULE_LICENSEs out specifically because I wanted to
> avoid getting into hundreds of simultaneous license flamewars while
> trying to get *a different thing entirely* into the kernel (kallmodsyms,
> which depends on modules.builtin.objs being correct).
> 
> I still don't want to get into hundreds of simultaneous license
> flamewars or get my employer into legal hot water, so I think I'll leave
> things commented out and let individual maintainers decide whether they
> want to reconcile any contradictory info that may exist or not (and as
> noted *most* of these are conflicting.)
> 
> 
> This email is the closest thing I have to indicating what Luis would
> prefer (and the only reason I'm doing this is because I need it before
> Luis's modules.builtin.objs change can work):
> 
> <https://lore.kernel.org/linux-modules/Y5AgMuMu75gne6Ka@bombadil.infradead.org/>
> 
> Yes, Luis thinks we can just use SPDX, but given that they are usually
> different, making such a change seems well beyond my pay grade. Even in
> the PCI domain, we see (second column, MODULE_LICENSE: third: SPDX,
> sorry about the line lengths).
> 
> drivers/pci/controller/dwc/pcie-histb.c:		GPL v2		// SPDX-License-Identifier: GPL-2.0
> drivers/pci/controller/mobiveil/pcie-mobiveil-plat.c:	GPL v2		// SPDX-License-Identifier: GPL-2.0
> drivers/pci/controller/pci-tegra.c: 			GPL		// SPDX-License-Identifier: GPL-2.0+
> drivers/pci/controller/pci-versatile.c:			GPL v2		// SPDX-License-Identifier: GPL-2.0
> drivers/pci/controller/pcie-hisi-error.c:		GPL v2		// SPDX-License-Identifier: GPL-2.0
> drivers/pci/controller/pcie-microchip-host.c:		GPL		// SPDX-License-Identifier: GPL-2.0
> drivers/pci/endpoint/pci-ep-cfs.c:			GPL v2		// SPDX-License-Identifier: GPL-2.0
> drivers/pci/endpoint/pci-epc-core.c:			GPL v2		// SPDX-License-Identifier: GPL-2.0
> drivers/pci/endpoint/pci-epc-mem.c:			GPL v2		// SPDX-License-Identifier: GPL-2.0
> drivers/pci/endpoint/pci-epf-core.c:			GPL v2		// SPDX-License-Identifier: GPL-2.0
> drivers/pci/hotplug/acpiphp_core.c:			GPL		// SPDX-License-Identifier: GPL-2.0+
> drivers/pci/hotplug/shpchp_core.c:			GPL		// SPDX-License-Identifier: GPL-2.0+
> 
> Not much in the way of consistency here: GPL sometimes means 2.0+ but
> sometimes it means 2.0. GPL v2 appears to consistently mean GPL-2.0, but
> if you look at other affected modules you soon see inconsistency:
> 
> drivers/powercap/powercap_sys.c: GPL v2		// SPDX-License-Identifier: GPL-2.0-only
> drivers/firmware/imx/imx-scu.c: GPL v2		// SPDX-License-Identifier: GPL-2.0+
> arch/x86/crypto/blake2s-glue.c: GPL v2		// SPDX-License-Identifier: GPL-2.0 OR MIT
> drivers/iommu/sun50i-iommu.c: Dual BSD/GPL	// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> 
> We even have
> 
> drivers/gpu/drm/drm_mipi_dsi.c: "GPL and additional rights" (header is
> non-SPDX -- a BSD license header with advertising clause!)
> 
> So SPDX is usually more precise than the MODULE_LICENSE, but is it more
> *accurate*? I have no idea, and I don't see how I could possibly know:
> going by the presence of advertising clauses that obviously nobody is
> obeying it doesn't seem like we can trust header comments to be any more
> accurate than MODULE_LICENSE. Best to just leave both in (and comment it
> out so it has no side-effects on the build any more, which is all I'm
> after).

You are overcomplicating things.

First, GPL == GPL v2.
Second, SPDX is the right one. License in module is needed to limit
EXPORT_SYMBOL* exposure.
Third, we have git log and git blame to audit and revert any change.
There is no need in leaving (even as commented) dead code.

Thanks

> 
> -- 
> NULL && (void)