linux-kernel - Re: [PATCH v3 1/3] vdso: Switch get/put unaligned from packed struct to memcpy

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Message-ID: <CAP-5=fW=tWLwLoozZfVHQ7QgKS3ACf0_LxztGcs5mhpAO23sww@mail.gmail.com>
Date: Mon, 18 Aug 2025 09:03:16 -0700
From: Ian Rogers <irogers@...gle.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: kernel test robot <lkp@...el.com>, Eric Biggers <ebiggers@...gle.com>, Yuzhuo Jing <yuzhuo@...gle.com>, 
	Andy Lutomirski <luto@...nel.org>, Vincenzo Frascino <vincenzo.frascino@....com>, 
	Arnaldo Carvalho de Melo <acme@...hat.com>, Al Viro <viro@...iv.linux.org.uk>, 
	Christophe Leroy <christophe.leroy@...roup.eu>, "Jason A. Donenfeld" <Jason@...c4.com>, 
	linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org, 
	llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev
Subject: Re: [PATCH v3 1/3] vdso: Switch get/put unaligned from packed struct
 to memcpy

On Tue, Jul 22, 2025 at 10:00 AM Ian Rogers <irogers@...gle.com> wrote:
>
> On Tue, Jul 22, 2025 at 9:44 AM Ian Rogers <irogers@...gle.com> wrote:
> >
> > On Tue, Jul 22, 2025 at 8:56 AM Thomas Gleixner <tglx@...utronix.de> wrote:
> > >
> > > Ian!
> > >
> > > On Sat, Jul 05 2025 at 08:05, kernel test robot wrote:
> > > > kernel test robot noticed the following build warnings:
> > > >
> > > > [auto build test WARNING on linus/master]
> > > > [also build test WARNING on tip/timers/vdso v6.16-rc4 next-20250704]
> > > > [cannot apply to acme/perf/core]
> > > > [If your patch is applied to the wrong git tree, kindly drop us a note.
> > > > And when submitting patch, we suggest to use '--base' as documented in
> > > > https://git-scm.com/docs/git-format-patch#_base_tree_information]
> > > >
> > > > url:    https://github.com/intel-lab-lkp/linux/commits/Ian-Rogers/vdso-Switch-get-put-unaligned-from-packed-struct-to-memcpy/20250626-135005
> > > > base:   linus/master
> > > > patch link:    https://lore.kernel.org/r/20250626054826.433453-2-irogers%40google.com
> > > > patch subject: [PATCH v3 1/3] vdso: Switch get/put unaligned from packed struct to memcpy
> > > > config: s390-randconfig-002-20250705 (https://download.01.org/0day-ci/archive/20250705/202507050736.b4hX0Xks-lkp@intel.com/config)
> > > > compiler: clang version 21.0.0git (https://github.com/llvm/llvm-project 61529d9e36fa86782a2458e6bdeedf7f376ef4b5)
> > > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250705/202507050736.b4hX0Xks-lkp@intel.com/reproduce)
> > > >
> > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > > > the same patch/commit), kindly add following tags
> > > > | Reported-by: kernel test robot <lkp@...el.com>
> > > > | Closes: https://lore.kernel.org/oe-kbuild-all/202507050736.b4hX0Xks-lkp@intel.com/
> > > >
> > > > All warnings (new ones prefixed by >>):
> > > >
> > > >    In file included from arch/s390/boot/decompressor.c:48:
> > > >    In file included from arch/s390/include/uapi/../../../../lib/decompress_unlz4.c:10:
> > > >    In file included from arch/s390/include/uapi/../../../../lib/lz4/lz4_decompress.c:36:
> > > >>> arch/s390/include/uapi/../../../../lib/lz4/lz4defs.h:109:9: warning: default initialization of an object of type 'typeof (*((const U16 *)ptr))' (aka 'const unsigned short') leaves the object uninitialized [-Wdefault-const-init-var-unsafe]
> > > >      109 |         return get_unaligned((const U16 *)ptr);
> > > >          |                ^
> > >
> > > Any update on this one?

Hi Thomas,

I sent out a v4 patch set:
https://lore.kernel.org/lkml/20250722215754.672330-1-irogers@google.com/
which has no bot complaints but also no reviews. It side stepped some
of the challenges by always operating on pointer types. If people
could PTAL it would be appreciated as then we can pick up the changes
in tools and drop:
https://web.git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/commit/tools/perf/Makefile.config?h=perf-tools-next&id=55a18d2f3ff79c9082225f44e0abbaea6286bf99

Thanks,
Ian