From: Michael Ellerman <mpe@ellerman.id.au>
To: Arnd Bergmann <arnd@arndb.de>,
Adrian Hunter <adrian.hunter@intel.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
John Stultz <jstultz@google.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
Naresh Kamboju <naresh.kamboju@linaro.org>,
"x86@kernel.org" <x86@kernel.org>,
"Aneesh Kumar K.V" <aneesh.kumar@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Nicholas Piggin <npiggin@gmail.com>,
Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Anna-Maria Gleixner <anna-maria@linutronix.de>,
Stephen Boyd <sboyd@kernel.org>,
Randy Dunlap <rdunlap@infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Sven Schnelle <svens@linux.ibm.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH] bug: Fix no-return-statement warning with !CONFIG_BUG
Date: Mon, 15 Apr 2024 12:19:50 +1000 [thread overview]
Message-ID: <875xwjcqpl.fsf@mail.lhotse> (raw)
In-Reply-To: <dd6653b2-3a88-4b95-af13-c6fda5b27b39@app.fastmail.com>
"Arnd Bergmann" <arnd@arndb.de> writes:
> On Thu, Apr 11, 2024, at 11:27, Adrian Hunter wrote:
>> On 11/04/24 11:22, Christophe Leroy wrote:
>>> Le 11/04/2024 à 10:12, Christophe Leroy a écrit :
>>>>
>>>> Looking at the report, I think the correct fix should be to use
>>>> BUILD_BUG() instead of BUG()
>>>
>>> I confirm the error goes away with the following change to next-20240411
>>> on powerpc tinyconfig with gcc 13.2
>>>
>>> diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
>>> index 4e18db1819f8..3d5ac0cdd721 100644
>>> --- a/kernel/time/timekeeping.c
>>> +++ b/kernel/time/timekeeping.c
>>> @@ -282,7 +282,7 @@ static inline void timekeeping_check_update(struct
>>> timekeeper *tk, u64 offset)
>>> }
>>> static inline u64 timekeeping_debug_get_ns(const struct tk_read_base *tkr)
>>> {
>>> - BUG();
>>> + BUILD_BUG();
>>> }
>>> #endif
>>>
>>
>> That is fragile because it depends on defined(__OPTIMIZE__),
>> so it should still be:
>
> If there is a function that is defined but that must never be
> called, I think we are doing something wrong.
It's a pretty inevitable result of using IS_ENABLED(), which the docs
encourage people to use.
In this case it could easily be turned into a build error by just making
it an extern rather than a static inline.
But I think Christophe's solution is actually better, because it's more
explicit, ie. this function should not be called and if it is that's a
build time error.
cheers
next prev parent reply other threads:[~2024-04-15 2:19 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-10 15:32 [PATCH] bug: Fix no-return-statement warning with !CONFIG_BUG Adrian Hunter
2024-04-10 15:32 ` Adrian Hunter
2024-04-10 17:02 ` Naresh Kamboju
2024-04-10 17:02 ` Naresh Kamboju
2024-04-10 20:05 ` [tip: timers/urgent] " tip-bot2 for Adrian Hunter
2024-04-11 7:04 ` [PATCH] " Arnd Bergmann
2024-04-11 7:04 ` Arnd Bergmann
2024-04-11 7:16 ` Adrian Hunter
2024-04-11 7:16 ` Adrian Hunter
2024-04-11 7:56 ` Arnd Bergmann
2024-04-11 9:03 ` Adrian Hunter
2024-04-11 10:27 ` David Laight
2024-04-11 8:13 ` Christophe Leroy
2024-04-11 8:13 ` Christophe Leroy
2024-04-11 8:22 ` Christophe Leroy
2024-04-11 8:22 ` Christophe Leroy
2024-04-11 9:27 ` Adrian Hunter
2024-04-11 9:27 ` Adrian Hunter
2024-04-11 11:26 ` Arnd Bergmann
2024-04-11 11:26 ` Arnd Bergmann
2024-04-15 2:19 ` Michael Ellerman [this message]
2024-04-15 15:35 ` Arnd Bergmann
2024-04-15 15:35 ` Arnd Bergmann
2024-04-15 17:07 ` Christophe Leroy
2024-04-15 17:32 ` Arnd Bergmann
2024-04-15 17:32 ` Arnd Bergmann
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