* [PATCH] zlib: define get_unaligned16() only when used
@ 2020-11-24 10:40 Lukas Bulwahn
2020-11-24 11:08 ` Jann Horn
0 siblings, 1 reply; 6+ messages in thread
From: Lukas Bulwahn @ 2020-11-24 10:40 UTC (permalink / raw)
To: Jann Horn, Andrew Morton
Cc: Arnd Bergmann, Tom Rix, Nathan Chancellor, Nick Desaulniers,
clang-built-linux, kernel-janitors, linux-kernel, Lukas Bulwahn
Since commit acaab7335bd6 ("lib/zlib: remove outdated and incorrect
pre-increment optimization"), get_unaligned16() is only used when
!CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS.
Hence, make CC=clang W=1 warns:
lib/zlib_inflate/inffast.c:20:1:
warning: unused function 'get_unaligned16' [-Wunused-function]
Define get_unaligned16() only when it is actually used.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
---
applies cleanly on current master and next-20201124
Jann, please ack.
Andrew, please pick this minor non-urgent clean-up patch.
lib/zlib_inflate/inffast.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
index ed1f3df27260..ca66d9008228 100644
--- a/lib/zlib_inflate/inffast.c
+++ b/lib/zlib_inflate/inffast.c
@@ -15,7 +15,8 @@ union uu {
unsigned char b[2];
};
-/* Endian independed version */
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+/* Endian independent version */
static inline unsigned short
get_unaligned16(const unsigned short *p)
{
@@ -26,6 +27,7 @@ get_unaligned16(const unsigned short *p)
mm.b[1] = b[1];
return mm.us;
}
+#endif
/*
Decode literal, length, and distance codes and write out the resulting
--
2.17.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] zlib: define get_unaligned16() only when used
2020-11-24 10:40 [PATCH] zlib: define get_unaligned16() only when used Lukas Bulwahn
@ 2020-11-24 11:08 ` Jann Horn
2020-11-24 11:50 ` Christoph Hellwig
0 siblings, 1 reply; 6+ messages in thread
From: Jann Horn @ 2020-11-24 11:08 UTC (permalink / raw)
To: Lukas Bulwahn
Cc: Andrew Morton, Arnd Bergmann, Tom Rix, Nathan Chancellor,
Nick Desaulniers, clang-built-linux, kernel-janitors,
kernel list
On Tue, Nov 24, 2020 at 11:40 AM Lukas Bulwahn <lukas.bulwahn@gmail.com> wrote:
> Since commit acaab7335bd6 ("lib/zlib: remove outdated and incorrect
> pre-increment optimization"), get_unaligned16() is only used when
> !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS.
>
> Hence, make CC=clang W=1 warns:
>
> lib/zlib_inflate/inffast.c:20:1:
> warning: unused function 'get_unaligned16' [-Wunused-function]
>
> Define get_unaligned16() only when it is actually used.
>
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
AFAICS a nicer option would be to "#include <asm/unaligned.h>" and
then use "get_unaligned", which should automatically do the right
thing everywhere and remove the need for defining get_unaligned16()
and checking CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS entirely?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] zlib: define get_unaligned16() only when used
2020-11-24 11:08 ` Jann Horn
@ 2020-11-24 11:50 ` Christoph Hellwig
2020-11-24 11:56 ` Arnd Bergmann
0 siblings, 1 reply; 6+ messages in thread
From: Christoph Hellwig @ 2020-11-24 11:50 UTC (permalink / raw)
To: Jann Horn
Cc: Lukas Bulwahn, Andrew Morton, Arnd Bergmann, Tom Rix,
Nathan Chancellor, Nick Desaulniers, clang-built-linux,
kernel-janitors, kernel list
On Tue, Nov 24, 2020 at 12:08:40PM +0100, Jann Horn wrote:
> > Since commit acaab7335bd6 ("lib/zlib: remove outdated and incorrect
> > pre-increment optimization"), get_unaligned16() is only used when
> > !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS.
> >
> > Hence, make CC=clang W=1 warns:
> >
> > lib/zlib_inflate/inffast.c:20:1:
> > warning: unused function 'get_unaligned16' [-Wunused-function]
> >
> > Define get_unaligned16() only when it is actually used.
> >
> > Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
>
> AFAICS a nicer option would be to "#include <asm/unaligned.h>" and
> then use "get_unaligned", which should automatically do the right
> thing everywhere and remove the need for defining get_unaligned16()
> and checking CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS entirely?
Yes, that is the right thing to do.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] zlib: define get_unaligned16() only when used
2020-11-24 11:50 ` Christoph Hellwig
@ 2020-11-24 11:56 ` Arnd Bergmann
2020-11-24 12:00 ` Lukas Bulwahn
2020-11-24 13:31 ` David Laight
0 siblings, 2 replies; 6+ messages in thread
From: Arnd Bergmann @ 2020-11-24 11:56 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Jann Horn, Lukas Bulwahn, Andrew Morton, Arnd Bergmann, Tom Rix,
Nathan Chancellor, Nick Desaulniers, clang-built-linux,
kernel-janitors, kernel list
On Tue, Nov 24, 2020 at 12:51 PM Christoph Hellwig <hch@infradead.org> wrote:
> On Tue, Nov 24, 2020 at 12:08:40PM +0100, Jann Horn wrote:
> > > Since commit acaab7335bd6 ("lib/zlib: remove outdated and incorrect
> > > pre-increment optimization"), get_unaligned16() is only used when
> > > !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS.
> > >
> > > Hence, make CC=clang W=1 warns:
> > >
> > > lib/zlib_inflate/inffast.c:20:1:
> > > warning: unused function 'get_unaligned16' [-Wunused-function]
> > >
> > > Define get_unaligned16() only when it is actually used.
> > >
> > > Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
> >
> > AFAICS a nicer option would be to "#include <asm/unaligned.h>" and
> > then use "get_unaligned", which should automatically do the right
> > thing everywhere and remove the need for defining get_unaligned16()
> > and checking CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS entirely?
>
> Yes, that is the right thing to do.
It's possible that this didn't work when the code was originally added:
The decompressor functions are called from the compressed boot path,
which is a bit limited regarding which headers it can include, at least
on some architectures.
I would recommend test-building this for all architectures that include
../../../../lib/decompress_inflate.c from their boot code.
Arnd
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] zlib: define get_unaligned16() only when used
2020-11-24 11:56 ` Arnd Bergmann
@ 2020-11-24 12:00 ` Lukas Bulwahn
2020-11-24 13:31 ` David Laight
1 sibling, 0 replies; 6+ messages in thread
From: Lukas Bulwahn @ 2020-11-24 12:00 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Christoph Hellwig, Jann Horn, Andrew Morton, Arnd Bergmann,
Tom Rix, Nathan Chancellor, Nick Desaulniers, clang-built-linux,
kernel-janitors, kernel list
On Tue, Nov 24, 2020 at 12:56 PM Arnd Bergmann <arnd@kernel.org> wrote:
>
> On Tue, Nov 24, 2020 at 12:51 PM Christoph Hellwig <hch@infradead.org> wrote:
> > On Tue, Nov 24, 2020 at 12:08:40PM +0100, Jann Horn wrote:
> > > > Since commit acaab7335bd6 ("lib/zlib: remove outdated and incorrect
> > > > pre-increment optimization"), get_unaligned16() is only used when
> > > > !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS.
> > > >
> > > > Hence, make CC=clang W=1 warns:
> > > >
> > > > lib/zlib_inflate/inffast.c:20:1:
> > > > warning: unused function 'get_unaligned16' [-Wunused-function]
> > > >
> > > > Define get_unaligned16() only when it is actually used.
> > > >
> > > > Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
> > >
> > > AFAICS a nicer option would be to "#include <asm/unaligned.h>" and
> > > then use "get_unaligned", which should automatically do the right
> > > thing everywhere and remove the need for defining get_unaligned16()
> > > and checking CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS entirely?
> >
> > Yes, that is the right thing to do.
>
> It's possible that this didn't work when the code was originally added:
> The decompressor functions are called from the compressed boot path,
> which is a bit limited regarding which headers it can include, at least
> on some architectures.
>
> I would recommend test-building this for all architectures that include
> ../../../../lib/decompress_inflate.c from their boot code.
>
Jann, Christoph, Arnd, thanks for the advice. I will start to look
into this immediately.
Lukas
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [PATCH] zlib: define get_unaligned16() only when used
2020-11-24 11:56 ` Arnd Bergmann
2020-11-24 12:00 ` Lukas Bulwahn
@ 2020-11-24 13:31 ` David Laight
1 sibling, 0 replies; 6+ messages in thread
From: David Laight @ 2020-11-24 13:31 UTC (permalink / raw)
To: 'Arnd Bergmann', Christoph Hellwig
Cc: Jann Horn, Lukas Bulwahn, Andrew Morton, Arnd Bergmann, Tom Rix,
Nathan Chancellor, Nick Desaulniers, clang-built-linux,
kernel-janitors, kernel list
From: Arnd Bergmann
> Sent: 24 November 2020 11:57
>
> On Tue, Nov 24, 2020 at 12:51 PM Christoph Hellwig <hch@infradead.org> wrote:
> > On Tue, Nov 24, 2020 at 12:08:40PM +0100, Jann Horn wrote:
> > > > Since commit acaab7335bd6 ("lib/zlib: remove outdated and incorrect
> > > > pre-increment optimization"), get_unaligned16() is only used when
> > > > !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS.
> > > >
> > > > Hence, make CC=clang W=1 warns:
> > > >
> > > > lib/zlib_inflate/inffast.c:20:1:
> > > > warning: unused function 'get_unaligned16' [-Wunused-function]
> > > >
> > > > Define get_unaligned16() only when it is actually used.
> > > >
> > > > Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
> > >
> > > AFAICS a nicer option would be to "#include <asm/unaligned.h>" and
> > > then use "get_unaligned", which should automatically do the right
> > > thing everywhere and remove the need for defining get_unaligned16()
> > > and checking CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS entirely?
> >
> > Yes, that is the right thing to do.
>
> It's possible that this didn't work when the code was originally added:
> The decompressor functions are called from the compressed boot path,
> which is a bit limited regarding which headers it can include, at least
> on some architectures.
>
> I would recommend test-building this for all architectures that include
> ../../../../lib/decompress_inflate.c from their boot code.
Plausibly it could include a different header that defined the required
items for those builds.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
^ permalink raw reply [flat|nested] 6+ messages in thread
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2020-11-24 10:40 [PATCH] zlib: define get_unaligned16() only when used Lukas Bulwahn
2020-11-24 11:08 ` Jann Horn
2020-11-24 11:50 ` Christoph Hellwig
2020-11-24 11:56 ` Arnd Bergmann
2020-11-24 12:00 ` Lukas Bulwahn
2020-11-24 13:31 ` David Laight
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