Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <ed9b8268-0128-0486-04a3-54f343afd38b@gmail.com>
Date:   Thu, 6 Oct 2022 13:33:50 -0700
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.3.1
Subject: Re: [PATCH] include/uapi/linux/swab: Fix potentially missing
 __always_inline
Content-Language: en-US
To:     Nathan Chancellor <nathan@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>
Cc:     linux-kernel@vger.kernel.org,
        =?UTF-8?Q?Petr_Van=c4=9bk?= <arkamar@atlas.cz>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, Justin Stitt <jstitt007@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Ingo Molnar <mingo@kernel.org>,
        "open list:CLANG/LLVM BUILD SUPPORT" <llvm@lists.linux.dev>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        "open list:PERFORMANCE EVENTS SUBSYSTEM" 
        <linux-perf-users@vger.kernel.org>, mmayer@broadcom.com,
        Khem Raj <raj.khem@gmail.com>,
        Philippe Ombredanne <pombredanne@nexb.com>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Thomas Gleixner <tglx@linutronix.de>
References: <20220927215256.528619-1-f.fainelli@gmail.com>
 <YzTMUpd6HbHmZu8f@dev-arch.thelio-3990X>
From:   Florian Fainelli <f.fainelli@gmail.com>
In-Reply-To: <YzTMUpd6HbHmZu8f@dev-arch.thelio-3990X>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

Hi Nathan,

On 9/28/2022 3:36 PM, Nathan Chancellor wrote:
> Hi Florian,
> 
> On Tue, Sep 27, 2022 at 02:52:56PM -0700, Florian Fainelli wrote:
>> From: Matt Redfearn <matt.redfearn@mips.com>
>>
>> Commit bc27fb68aaad ("include/uapi/linux/byteorder, swab: force inlining
>> of some byteswap operations") added __always_inline to swab functions
>> and commit 283d75737837 ("uapi/linux/stddef.h: Provide __always_inline to
>> userspace headers") added a definition of __always_inline for use in
>> exported headers when the kernel's compiler.h is not available.
>>
>> However, since swab.h does not include stddef.h, if the header soup does
>> not indirectly include it, the definition of __always_inline is missing,
>> resulting in a compilation failure, which was observed compiling the
>> perf tool using exported headers containing this commit:
>>
>> In file included from /usr/include/linux/byteorder/little_endian.h:12:0,
>>                   from /usr/include/asm/byteorder.h:14,
>>                   from tools/include/uapi/linux/perf_event.h:20,
>>                   from perf.h:8,
>>                   from builtin-bench.c:18:
>> /usr/include/linux/swab.h:160:8: error: unknown type name `__always_inline'
>>   static __always_inline __u16 __swab16p(const __u16 *p)
>>
>> Fix this by replacing the inclusion of linux/compiler.h with
>> linux/stddef.h to ensure that we pick up that definition if required,
>> without relying on it's indirect inclusion. compiler.h is then included
>> indirectly, via stddef.h.
>>
>> Fixes: 283d75737837 ("uapi/linux/stddef.h: Provide __always_inline to userspace headers")
>> Signed-off-by: Matt Redfearn <matt.redfearn@mips.com>
>> Reviewed-by: Petr Vaněk <arkamar@atlas.cz>
>> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> 
> I took this through my kernel build matrix and did not see any new
> issues.
> 
> Tested-by: Nathan Chancellor <nathan@kernel.org>

Great thanks! Since this is really useful for kernel-headers in 
toolchains, it would be great to get this picked up. Arnd is this 
something that would go via your tree?
-- 
Florian