linux-kernel - Re: [PATCH v1 1/1] mtd: mtdpart: Do not supply NULL to printf()

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Message-ID: <Z9LLOthvgonKIc6U@smile.fi.intel.com>
Date: Thu, 13 Mar 2025 14:10:34 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Zhihao Cheng <chengzhihao1@...wei.com>
Cc: linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Miquel Raynal <miquel.raynal@...tlin.com>,
	Richard Weinberger <richard@....at>,
	Vignesh Raghavendra <vigneshr@...com>
Subject: Re: [PATCH v1 1/1] mtd: mtdpart: Do not supply NULL to printf()

On Thu, Mar 13, 2025 at 06:54:40PM +0800, Zhihao Cheng wrote:
> 在 2025/3/13 17:09, Andy Shevchenko 写道:
> > On Thu, Mar 13, 2025 at 09:24:21AM +0800, Zhihao Cheng wrote:
> > > 在 2025/3/13 4:16, Andy Shevchenko 写道:
> > > > Compiler is not happy about NULL being supplied as printf() parameter:
> > > 
> > > printf -> printk? The title has the same issue.
> > > > 
> > > > drivers/mtd/mtdpart.c:693:34: error: ‘%s’ directive argument is null [-Werror=format-overflow=]
> > > > 
> > > > Replace that with "(null)" to fix compilation error.
> > 
> > > Reviewed-by: Zhihao Cheng <chengzhihao1@...wei.com>
> > 
> > Thank you!
> > 
> > But I think my approach is a hack, the best is to move this message to the
> > after the follow up conditional and drop that ternary completely as we have
> > already another debug message before that. So, the parser == NULL can be
> > deducted from the appearance of the one and not the other one.
> > 
> > I'll send a v2.
> > 
> > > >    			if (!parser && !request_module("%s", *types))
> > > >    				parser = mtd_part_parser_get(*types);
> > > >    			pr_debug("%s: got parser %s\n", master->name,
> > > > -				parser ? parser->name : NULL);
> > > > +				parser ? parser->name : "(null)");
> > > >    			if (!parser)
> > > >    				continue;
> > 
> > (move it here)
> 
> After looking through 8e2c992b59fc("mtd: mtdpart: add debug prints to
> partition parser.") and 01f9c7240a90("mtd: partitions: factor out code
> calling parser"), I think we'd better keep the debug message before the
> condition 'if (!parser)', it is used to inform us whether we get a parser
> and which name it is. And the debug message in mtd_part_do_parse informs us
> the result of the 'parser->parse_fn'.

See v2, please. From information point of view no piece would be lost.

> > > >    			ret = mtd_part_do_parse(parser, master, &pparts, data);

-- 
With Best Regards,
Andy Shevchenko