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From: Nathan Chancellor <nathan@kernel.org>
To: kbuild-all@lists.01.org
Subject: Re: [PATCH v9 01/12] user_events: Add minimal support for trace_event into ftrace
Date: Fri, 14 Jan 2022 09:29:06 -0700
Message-ID: <YeGk0nIH9x91k01I@archlinux-ax161>
In-Reply-To: <202201142322.DpkhCCS2-lkp@intel.com>
List-Id: <oe-kbuild-all.lists.linux.dev>

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On Fri, Jan 14, 2022 at 11:30:05PM +0800, kernel test robot wrote:
> Hi Beau,
> =

> Thank you for the patch! Perhaps something to improve:
> =

> [auto build test WARNING on 85c62c8c3749eec02ba81217bdcac26867dc262e]
> =

> url:    https://github.com/0day-ci/linux/commits/Beau-Belgrave/user_event=
s-Enable-user-processes-to-create-and-write-to-trace-events/20220112-014042
> base:   85c62c8c3749eec02ba81217bdcac26867dc262e
> config: hexagon-allmodconfig (https://download.01.org/0day-ci/archive/202=
20114/202201142322.DpkhCCS2-lkp(a)intel.com/config)
> compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 82c8=
aca93488730ce8f66101e0f3538f14b551dd)
> reproduce (this is a W=3D1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbi=
n/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://github.com/0day-ci/linux/commit/a5a2d34cbaeb90d281d8c13=
c753f4aaaa447ec11
>         git remote add linux-review https://github.com/0day-ci/linux
>         git fetch --no-tags linux-review Beau-Belgrave/user_events-Enable=
-user-processes-to-create-and-write-to-trace-events/20220112-014042
>         git checkout a5a2d34cbaeb90d281d8c13c753f4aaaa447ec11
>         # save the config file to linux build tree
>         mkdir build_dir
>         COMPILER_INSTALL_PATH=3D$HOME/0day COMPILER=3Dclang make.cross W=
=3D1 O=3Dbuild_dir ARCH=3Dhexagon SHELL=3D/bin/bash kernel/trace/ sound/soc=
/sof/
> =

> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> =

> All warnings (new ones prefixed by >>):
> =

> >> kernel/trace/trace_events_user.c:1027:14: warning: performing pointer =
arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithme=
tic]
>            return NULL + (*pos =3D=3D 0);
>                   ~~~~ ^
>    1 warning generated.
> =

> =

> vim +1027 kernel/trace/trace_events_user.c
> =

>   1024	=

>   1025	static void *user_seq_start(struct seq_file *m, loff_t *pos)
>   1026	{
> > 1027		return NULL + (*pos =3D=3D 0);
>   1028	}
>   1029	=

> =


Arnd, it looks like [1] never got picked up? That would help solve
this, as this function is the same as single_start(). Should it be
resent or pinged?

[1]: https://lore.kernel.org/r/20201028151202.3074398-1-arnd(a)kernel.org/

Cheers,
Nathan
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