Re: [PATCH] ARM: io: Fix namespace conflicts.

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

Hello,

On Wed, Oct 13, 2010 at 04:22:01PM +0530, Varadarajan, Charulatha wrote:
> From: Sourav Poddar <sourav.poddar@ti.com>
> 
> Having __v as the variable name for the definition of different macros leads to
> the namespace pollution. For example,
> readl(p)
> unrolls to:
> ({ u32 __v = ({ u32 __v = (( __u32)(__le32)(( __le32) ((void)0,
> *(volatile unsigned int *)((p))))); __v; }); __asm__ __volatile__ ("mcr
> p15,
> , %0, c7, c10, 5" : : "r" (0) : "memory"); __v; });
> 
> ({ u32 __v = ({ u32 __v
> causes sparse warning: "warning: symbol '__v' shadows an earlier one"
> 
> Using variable names which use the function name prefix across the
> various macros avoids the namespace pollution.
> 
> With this change, ~200 sparse warnings in omap2plus_defconfig build are
> fixed.
> 
> Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
> Signed-off-by: Charulatha V <charu@ti.com>
> Reviewed by: Nishanth Menon <nm@ti.com>
> ---
>  Links related to the previous discussions are as follows:
>  
>  http://www.spinics.net/lists/linux-omap/msg38569.html
>  http://marc.info/?t=128506336700011&r=1&w=2
> 
>  arch/arm/include/asm/io.h |   32 +++++++++++++++++++++-----------
>  1 files changed, 21 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
> index 1261b1f..01e4a7b 100644
> --- a/arch/arm/include/asm/io.h
> +++ b/arch/arm/include/asm/io.h
> @@ -131,11 +131,11 @@ static inline void __iomem *__typesafe_io(unsigned long addr)
>  #define outl(v,p)		__raw_writel((__force __u32) \
>  					cpu_to_le32(v),__io(p))
>  
> -#define inb(p)	({ __u8 __v = __raw_readb(__io(p)); __v; })
> -#define inw(p)	({ __u16 __v = le16_to_cpu((__force __le16) \
> -			__raw_readw(__io(p))); __v; })
> -#define inl(p)	({ __u32 __v = le32_to_cpu((__force __le32) \
> -			__raw_readl(__io(p))); __v; })
> +#define inb(p)	({ __u8 __inbv = __raw_readb(__io(p)); __inbv; })
> +#define inw(p)	({ __u16 __inwv = le16_to_cpu((__force __le16) \
> +			__raw_readw(__io(p))); __inwv; })
> +#define inl(p)	({ __u32 __inlv = le32_to_cpu((__force __le32) \
> +			__raw_readl(__io(p))); __inlv; })
I wonder if it's not better to make these static inlines instead.  Then
no naming conflicts can occur.  And maybe we'd catch some more strange
things because p gets a proper type.

I don't know how this influences gcc though.

Ah, and maybe some more tricks need to be applied, because at least some
macros can be overwritten per architecture.

Just my 0.02€
Uwe

>  
>  #define outsb(p,d,l)		__raw_writesb(__io(p),d,l)
>  #define outsw(p,d,l)		__raw_writesw(__io(p),d,l)
> @@ -200,9 +200,12 @@ extern void _memset_io(volatile void __iomem *, int, size_t);
>  #define __iowmb()		do { } while (0)
>  #endif
>  
> -#define readb(c)		({ u8  __v = readb_relaxed(c); __iormb(); __v; })
> -#define readw(c)		({ u16 __v = readw_relaxed(c); __iormb(); __v; })
> -#define readl(c)		({ u32 __v = readl_relaxed(c); __iormb(); __v; })
> +#define readb(c)		({ u8  __readbv = readb_relaxed(c); \
> +					 __iormb(); __readbv; })
> +#define readw(c)		({ u16 __readwv = readw_relaxed(c); \
> +					 __iormb(); __readwv; })
> +#define readl(c)		({ u32 __readlv = readl_relaxed(c);\
> +					 __iormb(); __readlv; })
>  
>  #define writeb(v,c)		({ __iowmb(); writeb_relaxed(v,c); })
>  #define writew(v,c)		({ __iowmb(); writew_relaxed(v,c); })
> @@ -258,9 +261,16 @@ extern void _memset_io(volatile void __iomem *, int, size_t);
>   * io{read,write}{8,16,32} macros
>   */
>  #ifndef ioread8
> -#define ioread8(p)	({ unsigned int __v = __raw_readb(p); __iormb(); __v; })
> -#define ioread16(p)	({ unsigned int __v = le16_to_cpu((__force __le16)__raw_readw(p)); __iormb(); __v; })
> -#define ioread32(p)	({ unsigned int __v = le32_to_cpu((__force __le32)__raw_readl(p)); __iormb(); __v; })
> +#define ioread8(p)	({ unsigned int __ioread8v = __raw_readb(p); \
> +					 __iormb(); __ioread8v; })
> +#define ioread16(p)	({ unsigned int __ioread16v = \
> +					 le16_to_cpu((__force __le16) \
> +					__raw_readw(p)); __iormb(); \
> +					 __ioread16v; })
> +#define ioread32(p)	({ unsigned int __ioread32v = \
> +					 le32_to_cpu((__force __le32) \
> +					__raw_readl(p)); __iormb(); \
> +					 __ioread32v; })
>  
>  #define iowrite8(v,p)	({ __iowmb(); (void)__raw_writeb(v, p); })
>  #define iowrite16(v,p)	({ __iowmb(); (void)__raw_writew((__force __u16)cpu_to_le16(v), p); })
> -- 
> 1.7.0.4
> 
> 
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> 

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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