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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Wed, 22 Dec 2021 13:46:47 +0100
Message-ID: <CAK8P3a19n3pa+hRfC-ToTPhH2hvgYY=mXo_u6ZWkbbSSY5_JAA@mail.gmail.com>
Subject: Re: [PATCH 03/13] riscv: compat: Add basic compat date type implementation
To:     Guo Ren <guoren@kernel.org>
Cc:     Arnd Bergmann <arnd@arndb.de>, Palmer Dabbelt <palmer@dabbelt.com>,
        Anup Patel <anup.patel@wdc.com>,
        gregkh <gregkh@linuxfoundation.org>,
        liush <liush@allwinnertech.com>, Wei Fu <wefu@redhat.com>,
        Drew Fustini <drew@beagleboard.org>,
        Wang Junqiang <wangjunqiang@iscas.ac.cn>,
        =?UTF-8?B?V2VpIFd1ICjlkLTkvJ8p?= <lazyparser@gmail.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        linux-csky@vger.kernel.org, Guo Ren <guoren@linux.alibaba.com>
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On Wed, Dec 22, 2021 at 1:03 PM Guo Ren <guoren@kernel.org> wrote:
> On Wed, Dec 22, 2021 at 1:13 AM Arnd Bergmann <arnd@arndb.de> wrote:
> > On Tue, Dec 21, 2021 at 5:35 PM <guoren@kernel.org> wrote:
> >
> > > +struct compat_stat {
> > > +       compat_ulong_t  st_dev;
> > > +       compat_ulong_t  st_ino;
> > > +       compat_uint_t   st_mode;
> > > +       compat_uint_t   st_nlink;
> >
> > You should not need a compat_stat, because native rv32 does not have a
> > stat() syscall.
> We need it:
>
> $ make ARCH=riscv CROSS_COMPILE=riscv64-unknown-linux-gnu-
> EXTRA_CFLAGS+=-g O=../build-riscv/ Image -j > /dev/null
> /home/guoren/source/kernel/riscv-linux/fs/stat.c: In function 'cp_compat_stat':
> /home/guoren/source/kernel/riscv-linux/fs/stat.c:645:21: error:
> storage size of 'tmp' isn't known
>   645 |  struct compat_stat tmp;

I think that's just a bug in fs/stat.c. Every other architecture so
far needed it,
just not riscv, so we should add an appropriate #ifdef here. I would replace
#ifdef CONFIG_COMPAT around these with __ARCH_WANT_COMPAT_STAT
and then change all other compat architectures to define that depending
on the configuration.

        Arnd