Broken __get_unaligned from <asm-generic/unaligned.h>

Broken __get_unaligned from <asm-generic/unaligned.h>

[Andreas Schwab]

__get_unaligned can't cope with const-qualified types:

drivers/char/vc_screen.c: In function 'vcs_write':
drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'
drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'
drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'
drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'

Signed-off-by: Andreas Schwab <schwab@suse.de>

--- linux-2.6.14/include/asm-generic/unaligned.h.~1~	2005-10-28 02:02:08.000000000 +0200
+++ linux-2.6.14/include/asm-generic/unaligned.h	2005-11-10 14:37:58.356107194 +0100
@@ -78,7 +78,7 @@ static inline void __ustw(__u16 val, __u
 
 #define __get_unaligned(ptr, size) ({		\
 	const void *__gu_p = ptr;		\
-	__typeof__(*(ptr)) val;			\
+	unsigned long val;			\
 	switch (size) {				\
 	case 1:					\
 		val = *(const __u8 *)__gu_p;	\
@@ -95,7 +95,7 @@ static inline void __ustw(__u16 val, __u
 	default:				\
 		bad_unaligned_access_length();	\
 	};					\
-	val;					\
+	(__typeof__(*(ptr)))val;		\
 })
 
 #define __put_unaligned(val, ptr, size)		\

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: Broken __get_unaligned from <asm-generic/unaligned.h>

[Russell King]

On Thu, Nov 10, 2005 at 03:42:05PM +0100, Andreas Schwab wrote:
> __get_unaligned can't cope with const-qualified types:
> 
> drivers/char/vc_screen.c: In function 'vcs_write':
> drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'
> drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'
> drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'
> drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'

What if get_unaligned is used with a u64 / long long type (which it is)?

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core

Re: Broken __get_unaligned from <asm-generic/unaligned.h>

[Andreas Schwab]

Russell King <rmk+lkml@arm.linux.org.uk> writes:

> On Thu, Nov 10, 2005 at 03:42:05PM +0100, Andreas Schwab wrote:
>> __get_unaligned can't cope with const-qualified types:
>> 
>> drivers/char/vc_screen.c: In function 'vcs_write':
>> drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'
>> drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'
>> drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'
>> drivers/char/vc_screen.c:422: error: assignment of read-only variable 'val'
>
> What if get_unaligned is used with a u64 / long long type (which it is)?

Oops, I missed that, it needs a different approach.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."