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List:       linux-kernel
Subject:    Re: [PATCH v2] xtensa: remove redundant flush_dcache_page and ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE macr
From:       Barry Song <21cnbao () gmail ! com>
Date:       2024-04-29 1:39:42
Message-ID: CAGsJ_4zF+pf9-Y0SB1NAJ3rnij4NB6CZ3HogjZZDPJaDgnQMpA () mail ! gmail ! com
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On Sun, Apr 28, 2024 at 7:05 AM Guenter Roeck <linux@roeck-us.net> wrote:
> 
> Hi,
> 
> On Tue, Mar 19, 2024 at 02:09:20PM +1300, Barry Song wrote:
> > From: Barry Song <v-songbaohua@oppo.com>
> > 
> > xtensa's flush_dcache_page() can be a no-op sometimes. There is a
> > generic implementation for this case in include/asm-generic/
> > cacheflush.h.
> > #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
> > static inline void flush_dcache_page(struct page *page)
> > {
> > }
> > 
> > #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 0
> > #endif
> > 
> > So remove the superfluous flush_dcache_page() definition, which also
> > helps silence potential build warnings complaining the page variable
> > passed to flush_dcache_page() is not used.
> > 
> > In file included from crypto/scompress.c:12:
> > include/crypto/scatterwalk.h: In function 'scatterwalk_pagedone':
> > include/crypto/scatterwalk.h:76:30: warning: variable 'page' set but not used \
> > [-Wunused-but-set-variable] 76 |                 struct page *page;
> > > ^~~~
> > crypto/scompress.c: In function 'scomp_acomp_comp_decomp':
> > > > crypto/scompress.c:174:38: warning: unused variable 'dst_page' \
> > > > [-Wunused-variable]
> > 174 |                         struct page *dst_page = sg_page(req->dst);
> > > 
> > 
> > The issue was originally reported on LoongArch by kernel test
> > robot (Huacai fixed it on LoongArch), then reported by Guenter
> > and me on xtensa.
> > 
> > This patch also removes lots of redundant macros which have
> > been defined by asm-generic/cacheflush.h.
> > 
> > Cc: Huacai Chen <chenhuacai@loongson.cn>
> > Cc: Herbert Xu <herbert@gondor.apana.org.au>
> > Reported-by: kernel test robot <lkp@intel.com>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202403091614.NeUw5zcv-lkp@intel.com/
> >                 
> > Reported-by: Barry Song <v-songbaohua@oppo.com>
> > Closes: https://lore.kernel.org/all/CAGsJ_4yDk1+axbte7FKQEwD7X2oxUCFrEc9M5YOS1BobfDFXPA@mail.gmail.com/
> >                 
> > Reported-by: Guenter Roeck <linux@roeck-us.net>
> > Closes: https://lore.kernel.org/all/aaa8b7d7-5abe-47bf-93f6-407942436472@roeck-us.net/
> >                 
> > Fixes: 77292bb8ca69 ("crypto: scomp - remove memcpy if sg_nents is 1 and pages \
> >                 are lowmem")
> > Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> 
> The mainline kernel still fails to build xtensa:allmodconfig.
> 
> Building xtensa:allmodconfig ... failed
> --------------
> Error log:
> crypto/scompress.c: In function 'scomp_acomp_comp_decomp':
> crypto/scompress.c:174:38: error: unused variable 'dst_page' \
> [-Werror=unused-variable] 174 |                         struct page *dst_page = \
> sg_page(req->dst); 
> This patch fixes the problem. Is there a chance to get it applied to the
> upstream kernel, or should I just stop build testing xtensa:allmodconfig ?

I'd prefer this can be applied upstream.

Hi Andrew, would you like to pull it?

> 
> Thanks,
> Guenter

Thanks
Barry


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