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Date: Wed, 19 Aug 2020 23:48:48 +0300
From: Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH v3 09/17] memblock: make memblock_debug and related
 functionality private
Message-ID: <20200819204848.GX752365@kernel.org>
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To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>, Baoquan He <bhe@redhat.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Borislav Petkov <bp@alien8.de>, Catalin Marinas <catalin.marinas@arm.com>, Christoph Hellwig <hch@lst.de>, Daniel Axtens <dja@axtens.net>, Dave Hansen <dave.hansen@linux.intel.com>, Emil Renner Berthing <kernel@esmil.dk>, Ingo Molnar <mingo@redhat.com>, Hari Bathini <hbathini@linux.ibm.com>, Marek Szyprowski <m.szyprowski@samsung.com>, Max Filippov <jcmvbkbc@gmail.com>, Michael Ellerman <mpe@ellerman.id.au>, Michal Simek <monstr@monstr.eu>, Mike Rapoport <rppt@linux.ibm.com>, Palmer Dabbelt <palmer@dabbelt.com>, Paul Mackerras <paulus@samba.org>, Paul Walmsley <paul.walmsley@sifive.com>, Peter Zijlstra <peterz@infradead.org>, Russell King <linux@armlinux.org.uk>, Stafford Horne <shorne@gmail.com>, Thomas Gleixner <tglx@linutronix.de>, Will Deacon <will@kernel.org>, Yoshinori Sato <ysato@users.sourceforge.jp>, clang-built-linux@googlegroups.com, iommu@lists.linux-foundation.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-c6x-dev@linux-c6x.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, linuxppc-dev@lists.ozlabs.org, openrisc@lists.librecores.org, sparclinux@vger.kernel.org, uclinux-h8-devel@lists.sourceforge.jp, x86@kernel.org

On Wed, Aug 19, 2020 at 12:24:05PM -0700, Andrew Morton wrote:
> On Tue, 18 Aug 2020 18:16:26 +0300 Mike Rapoport <rppt@kernel.org> wrote:
> 
> > From: Mike Rapoport <rppt@linux.ibm.com>
> > 
> > The only user of memblock_dbg() outside memblock was s390 setup code and it
> > is converted to use pr_debug() instead.
> > This allows to stop exposing memblock_debug and memblock_dbg() to the rest
> > of the kernel.
> > 
> > --- a/mm/memblock.c
> > +++ b/mm/memblock.c
> > @@ -137,7 +137,10 @@ struct memblock_type physmem = {
> >  	     i < memblock_type->cnt;					\
> >  	     i++, rgn = &memblock_type->regions[i])
> >  
> > -int memblock_debug __initdata_memblock;
> > +#define memblock_dbg(fmt, ...) \
> > +	if (memblock_debug) printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
> > +
> 
> checkpatch doesn't like this much.
> 
> ERROR: Macros starting with if should be enclosed by a do - while loop to avoid possible if/else logic defects
> #101: FILE: mm/memblock.c:140:
> +#define memblock_dbg(fmt, ...) \
> +	if (memblock_debug) printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
> 
> WARNING: Prefer [subsystem eg: netdev]_info([subsystem]dev, ... then dev_info(dev, ... then pr_info(...  to printk(KERN_INFO ...
> #102: FILE: mm/memblock.c:141:
> +	if (memblock_debug) printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
> 
> ERROR: trailing statements should be on next line
> #102: FILE: mm/memblock.c:141:
> +	if (memblock_debug) printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
> 
> 
> The first one is significant:
> 
> 	if (foo)
> 		memblock_dbg(...);
> 	else
> 		save_the_world();
> 
> could end up inadvertently destroying the planet.

Well, it didn't till now ;-)

> This?
> 
> --- a/mm/memblock.c~memblock-make-memblock_debug-and-related-functionality-private-fix
> +++ a/mm/memblock.c
> @@ -137,8 +137,11 @@ struct memblock_type physmem = {
>  	     i < memblock_type->cnt;					\
>  	     i++, rgn = &memblock_type->regions[i])
>  
> -#define memblock_dbg(fmt, ...) \
> -	if (memblock_debug) printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
> +#define memblock_dbg(fmt, ...)						\
> +	do {								\
> +		if (memblock_debug)					\
> +			pr_info(fmt, ##__VA_ARGS__);			\
> +	} while (0)

Sure, thanks!

>  static int memblock_debug __initdata_memblock;
>  static bool system_has_some_mirror __initdata_memblock = false;
> _
> 

-- 
Sincerely yours,
Mike.