linux-kernel - Re: How do I printk <type> correctly?

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Message-Id: <20081105102335.b1fd995d.randy.dunlap@oracle.com>
Date:	Wed, 5 Nov 2008 10:23:35 -0800
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: How do I printk <type> correctly?

On Thu, 23 Oct 2008 15:41:33 +0400 Alexey Dobriyan wrote:

> If variable is of Type	use	printk format specifier.
> ---------------------------------------------------------
> 		int			%d or %x
> 		unsigned int		%u or %x
> 		long			%ld ot %lx
> 		unsigned long		%lu or %lx
> 		long long		%lld or %llx
> 		unsigned long long	%llu or %llx
> 		size_t			%zu or %zx
> 		ssize_t			%zd or %zx

Add, or is this one too infrequent to be listed here?

		tcflag_t		%lu or %lx or %lo

Since tcflag_t is unsigned int (on most $ARCH-es) or unsigned long (on sparc32),
use a cast to (unsigned long)flag when printing it.

[Yes, a sparc32 build gets lots of printk format warnings when printing tcflag_t
values.]


> Raw pointer value SHOULD be printed with %p.
> 
> u64 SHOULD be printed with %llu/%llx, (unsigned long long):
> 
> 	printk("%llu", (unsigned long long)u64_var);
> 
> s64 SHOULD be printed with %lld/%llx, (long long):
> 
> 	printk("%lld", (long long)s64_var);
> 
> If type is dependent on config option (sector_t), use format specifier
> of biggest type and explicitly cast to it.
> 
> Reminder: sizeof() result is of type size_t.
> 
> Thank you for your cooperation.
> --

---
~Randy
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