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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Wed, 21 Apr 2021 13:57:34 +0200
Message-ID: <CAK8P3a0uXo+CLs2emsXE=-Zr+FjxV5k7AWNdGrN0fa37gwub8w@mail.gmail.com>
Subject: Re: [PATCH v3 3/3] asm-generic/io.h: Silence -Wnull-pointer-arithmetic
 warning on PCI_IOBASE
To:     Niklas Schnelle <schnelle@linux.ibm.com>
Cc:     David Laight <David.Laight@aculab.com>,
        Vineet Gupta <vgupta@synopsys.com>,
        "David S. Miller" <davem@davemloft.net>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        "clang-built-linux@googlegroups.com" 
        <clang-built-linux@googlegroups.com>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
        "linux-snps-arc@lists.infradead.org" 
        <linux-snps-arc@lists.infradead.org>,
        "sparclinux@vger.kernel.org" <sparclinux@vger.kernel.org>
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On Wed, Apr 21, 2021 at 1:50 PM Niklas Schnelle <schnelle@linux.ibm.com> wrote:
> On Wed, 2021-04-21 at 11:24 +0000, David Laight wrote:
> >
> > I suspect that this might be better not inlined
> > when PCI_IOBASE is undefined.
> >
> > Otherwise you get quite a lot of bloat from all the
> > WARN_ONCE() calls.
>
> Hmm, I was wondering if we should rather have a large ifdef block of
> all these functions stubbed to WARN_ONCE rather than in each function.
> As I understand it this would be necessary if we want the inline gone.
> They would still be static though so we still get a copy per
> compilation unit that uses it or am I misunderstanding?

I wouldn't worry too much about the size of known broken drivers during
compile testing. Also, since the functions are marked 'inline' and not
'__always_inline', the compiler is free to decide not to inline them if
the contents are excessively big, and since the strings are all identical,
they should be constant-folded.

If you want to make this a little smaller, using pr_warn_once()
would be a little smaller, but also give less information.

      Arnd