From: Randy Dunlap <rdunlap@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Howells <dhowells@redhat.com>,
Hulk Robot <hulkci@huawei.com>,
Zheng Zengkai <zhengzengkai@huawei.com>,
Tom Rix <trix@redhat.com>,
linux-afs@lists.infradead.org,
Marc Dionne <marc.dionne@auristor.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] afs: fix no return statement in function returning non-void
Date: Tue, 15 Jun 2021 18:38:41 -0700 [thread overview]
Message-ID: <c2002123-795c-20ae-677c-a35ba0e361af@infradead.org> (raw)
In-Reply-To: <CAHk-=whPPWYXKQv6YjaPQgQCf+78S+0HmAtyzO1cFMdcqQp5-A@mail.gmail.com>
On 6/15/21 5:32 PM, Linus Torvalds wrote:
> On Tue, Jun 15, 2021 at 4:58 PM Randy Dunlap <rdunlap@infradead.org> wrote:
>>
>> Some implementations of BUG() are macros, not functions,
>
> Not "some", I think. Most.
>
>> so "unreachable" is not applicable AFAIK.
>
> Sure it is. One common pattern is the x86 one:
>
> #define BUG() \
> do { \
> instrumentation_begin(); \
> _BUG_FLAGS(ASM_UD2, 0); \
> unreachable(); \
> } while (0)
duh.
> and that "unreachable()" is exactly what I'm talking about.
>
> So I repeat: what completely broken compiler / config / architecture
> is it that needs that "return 0" after a BUG() statement?
I have seen it on ia64 -- most likely GCC 9.3.0, but I'll have to
double check that.
> Because that environment is broken, and the warning is bogus and wrong.
>
> It might not be the compiler. It might be some architecture that does
> this wrong. It might be some very particular configuration that does
> something bad and makes the "unreachable()" not work (or not exist).
>
> But *that* is the bug that should be fixed. Not adding a pointless and
> incorrect line that makes no sense, just to hide the real bug.
next prev parent reply other threads:[~2021-06-16 1:38 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 11:55 [PATCH] afs: fix no return statement in function returning non-void David Howells
2021-06-15 12:03 ` David Howells
2021-06-15 14:49 ` Linus Torvalds
2021-06-15 23:58 ` Randy Dunlap
2021-06-16 0:32 ` Linus Torvalds
2021-06-16 1:38 ` Randy Dunlap [this message]
2021-06-16 2:19 ` Randy Dunlap
2021-06-16 3:15 ` Zheng Zengkai
2021-06-16 12:56 ` Tom Rix
2021-06-16 14:34 ` Linus Torvalds
2021-06-16 16:22 ` Tom Rix
2021-06-16 16:29 ` Linus Torvalds
2021-06-18 15:23 ` Arnd Bergmann
2021-06-16 13:41 ` David Howells
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