linux-kernel - Re: [PATCH] checkpatch: Check for %L for all integer formats (was: Re: [PATCH] fix printk format compiler warnings)

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Date:	Tue, 30 Sep 2008 14:14:40 +0100
From:	Andy Whitcroft <apw@...dowen.org>
To:	Geert Uytterhoeven <Geert.Uytterhoeven@...ycom.com>
Cc:	Jan Beulich <jbeulich@...ell.com>,
	Randy Dunlap <rdunlap@...otime.net>,
	Joel Schopp <jschopp@...tin.ibm.com>,
	Linux Kernel Development <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] checkpatch: Check for %L for all integer formats (was:
	Re: [PATCH] fix printk format compiler warnings)

On Tue, Sep 30, 2008 at 01:29:44PM +0200, Geert Uytterhoeven wrote:
> On Fri, 5 Sep 2008, Jan Beulich wrote:
> > %llx and the like cannot be used on u64-derived data types - they must
> > be cast to long long explicitly for arch-es where u64 is a typedef of
> > unsigned long (ia64 is where I observed the problem).
> 
> > -		printk(KERN_INFO "PCI: bridge %s io port: [%llx, %llx]\n", pci_name(dev), res->start, res->end);
> > +		printk(KERN_INFO "PCI: bridge %s io port: [%Lx, %Lx]\n",
> 
> > -		printk(KERN_INFO "PCI: bridge %s 32bit mmio: [%llx, %llx]\n", pci_name(dev), res->start, res->end);
> > +		printk(KERN_INFO "PCI: bridge %s 32bit mmio: [%Lx, %Lx]\n",
> 
> > -		printk(KERN_INFO "PCI: bridge %s %sbit mmio pref: [%llx, %llx]\n", pci_name(dev), (res->flags & PCI_PREF_RANGE_TYPE_64)?"64":"32",res->start, res->end);
> > +		printk(KERN_INFO "PCI: bridge %s %dbit mmio pref: [%Lx, %Lx]\n",
> 
> > -		printk(KERN_INFO "bus: %02x index %x %s: [%llx, %llx]\n", bus->number, i, (res->flags & IORESOURCE_IO)? "io port":"mmio", res->start, res->end);
> > +		printk(KERN_INFO "bus: %02x index %x %s: [%Lx, %Lx]\n",
> 
> Why did you replace `%ll' by `%L'?
> 
> While `L' is used as an internal flag in Linux' vsnprintf() implementation and
> is still supported because of historical (pre-C99) reasons, the `L' conversion
> qualifier is meant for the `long double' floating point type, as per C99.
> The recommended conversion qualifier for the `long long' integer type is `ll'.
> 
> Perhaps checkpatch should check for this? Ah, it already does for some of the
> integer formats. The patch below adds checks for the missing ones.

[...]

Yes that looks entirly reasonable to me.  Will queue it up with my next
batch for Andrew.

Thanks.

-apw
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