Re: [PATCH 8/8] kbuild, PCI: microchip: comment out MODULE_LICENSE in non-modules

From: Nick Alcock <nick.alcock@oracle.com>
To: Leon Romanovsky <leon@kernel.org>
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
Date: Mon, 13 Feb 2023 16:13:00 +0000	[thread overview]
Message-ID: <87k00ly25v.fsf@esperi.org.uk> (raw)
In-Reply-To: <Y+kx3fb2Lzlg+u5+@unreal> (Leon Romanovsky's message of "Sun, 12 Feb 2023 20:37:17 +0200")

[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).

-- 
NULL && (void)