From: Guo Ren <guoren@kernel.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@lst.de>,
"the arch/x86 maintainers" <x86@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"open list:BROADCOM NVRAM DRIVER" <linux-mips@vger.kernel.org>,
Parisc List <linux-parisc@vger.kernel.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-s390 <linux-s390@vger.kernel.org>,
sparclinux <sparclinux@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Jeff Layton <jlayton@kernel.org>,
"J. Bruce Fields" <bfields@fieldses.org>
Subject: Re: [PATCH 4/5] uapi: always define F_GETLK64/F_SETLK64/F_SETLKW64 in fcntl.h
Date: Wed, 12 Jan 2022 10:08:42 +0800 [thread overview]
Message-ID: <CAJF2gTS81o1bsAGj=016F=Nw7MszhsYa95cw6JLThjwW50YRpw@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a0mHC5=OOGV=sGnC9JqZWxzsJyZbTefnCtryQU3o3PY_g@mail.gmail.com>
On Tue, Jan 11, 2022 at 11:33 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Tue, Jan 11, 2022 at 9:35 AM Christoph Hellwig <hch@lst.de> wrote:
> >
> > The fcntl F_GETLK64/F_SETLK64/F_SETLKW64 are only implemented for the
> > 32-bit syscall APIs, but we also need them for compat handling on 64-bit
> > builds. Redefining them is error prone (as shown by the example that
> > parisc gets it wrong currently), so we should use the same defines for
> > both case. In theory we could try to hide them from userspace, but
> > given that only MIPS actually gets that right, while the asm-generic
> > version used by most architectures relies on a Kconfig symbol that can't
> > be relied on to be set properly by userspace is a clear indicator to not
> > bother.
> >
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > ---
>
> > diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h
> > index 98f4ff165b776..43d7c44031be0 100644
> > --- a/include/uapi/asm-generic/fcntl.h
> > +++ b/include/uapi/asm-generic/fcntl.h
> > @@ -116,13 +116,11 @@
> > #define F_GETSIG 11 /* for sockets. */
> > #endif
> >
> > -#ifndef CONFIG_64BIT
> > #ifndef F_GETLK64
> > #define F_GETLK64 12 /* using 'struct flock64' */
> > #define F_SETLK64 13
> > #define F_SETLKW64 14
> > #endif
> > -#endif
> >
> > #ifndef F_SETOWN_EX
> > #define F_SETOWN_EX 15
>
> This is a very subtle change to the exported UAPI header contents:
> On 64-bit architectures, the three unusable numbers are now always
> shown, rather than depending on a user-controlled symbol.
>
> This is probably what we want here for compatibility reasons, but I think
> it should be explained in the changelog text, and I'd like Jeff or Bruce
> to comment on it as well: the alternative here would be to make the
> uapi definition depend on __BITS_PER_LONG==32, which is
__BITS_PER_LONG==32 || __KERNEL__ just for kernel use in compat.
> technically the right thing to do but more a of a change.
>
> Arnd
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/
next prev parent reply other threads:[~2022-01-12 2:09 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-11 8:35 consolidate the compat fcntl definitions Christoph Hellwig
2022-01-11 8:35 ` [PATCH 1/5] uapi: remove the unused HAVE_ARCH_STRUCT_FLOCK64 define Christoph Hellwig
2022-01-11 8:35 ` [PATCH 2/5] uapi: simplify __ARCH_FLOCK{,64}_PAD a little Christoph Hellwig
2022-01-11 8:35 ` [PATCH 3/5] uapi: merge the 32-bit mips struct flock into the generic one Christoph Hellwig
2022-01-11 8:35 ` [PATCH 4/5] uapi: always define F_GETLK64/F_SETLK64/F_SETLKW64 in fcntl.h Christoph Hellwig
2022-01-11 15:33 ` Arnd Bergmann
2022-01-12 2:08 ` Guo Ren [this message]
2022-01-12 7:56 ` Christoph Hellwig
2022-01-12 8:28 ` Arnd Bergmann
2022-01-12 11:15 ` Jeff Layton
2022-01-12 12:08 ` Arnd Bergmann
2022-01-12 16:09 ` Christoph Hellwig
2022-01-11 8:35 ` [PATCH 5/5] compat: consolidate the compat_flock{,64} definition Christoph Hellwig
2022-01-11 9:52 ` David Laight
2022-01-11 15:46 ` consolidate the compat fcntl definitions Arnd Bergmann
2022-01-12 9:56 ` Sergey Shtylyov
-- strict thread matches above, loose matches on Subject: below --
2022-01-31 6:49 consolidate the compat fcntl definitions v2 Christoph Hellwig
2022-01-31 6:49 ` [PATCH 4/5] uapi: always define F_GETLK64/F_SETLK64/F_SETLKW64 in fcntl.h Christoph Hellwig
2022-01-31 13:38 ` Guo Ren
2022-02-01 3:02 ` Guo Ren
2022-02-01 3:07 ` Guo Ren
2021-04-12 8:55 consolidate the flock uapi definitions Christoph Hellwig
2021-04-12 8:55 ` [PATCH 4/5] uapi: always define F_GETLK64/F_SETLK64/F_SETLKW64 in fcntl.h Christoph Hellwig
2021-04-13 15:43 ` Helge Deller
2021-04-13 15:46 ` Christoph Hellwig
2021-04-13 15:58 ` Helge Deller
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