About
http://user-mode-linux.sourceforge.net/work/current/2.6/2.6.16-rc4/patches/uaccess-warning
I read the patch which was rejected and noticed that you put there style
changes to get_user. They should be kept while the rest of the patch thrown
away, obviously, as discussed, but reading that made me wonder at this
(changes are just whitespace fixups):
- const __typeof__(ptr) __private_ptr = ptr; \
- __typeof__(*(__private_ptr)) __private_val; \
[...]
- if (__copy_from_user(&__private_val, (__private_ptr), \
- sizeof(*(__private_ptr))) == 0) {\
Given that __private_ptr is a const pointer, __private_val is a const value,
where we store something with __copy_from_user.
That's likely why GCC complains.
To fix that, we should remove some excess constness. Try the attached patch (I
haven't GCC 4.1 installed).
Also, I wonder why all this complicate and extra type-checked calls are
needed.
The i386 source use typeof only in 1 case, for put_user:
when I put_user((short)b, (unsigned long *) c) I must first cast (i.e.
zero-extend) b to a long and only after write it to c; writing the 4/8 bytes
pointed to by &b would be meaningless.
All this IMHO, obviously.
--
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade
Index: linux-2.6.git/include/asm-um/uaccess.h
===================================================================
--- linux-2.6.git.orig/include/asm-um/uaccess.h
+++ linux-2.6.git/include/asm-um/uaccess.h
@@ -42,7 +42,7 @@
#define __get_user(x, ptr) \
({ \
const __typeof__(ptr) __private_ptr = ptr; \
- __typeof__(*(__private_ptr)) __private_val; \
+ __typeof__(*(ptr)) __private_val; \
int __private_ret = -EFAULT; \
(x) = (__typeof__(*(__private_ptr)))0; \
if (__copy_from_user(&__private_val, (__private_ptr), \
@@ -55,7 +55,7 @@
#define get_user(x, ptr) \
({ \
- const __typeof__((*(ptr))) __user *private_ptr = (ptr); \
+ __typeof__((*(ptr))) __user *private_ptr = (ptr); \
(access_ok(VERIFY_READ, private_ptr, sizeof(*private_ptr)) ? \
__get_user(x, private_ptr) : ((x) = 0, -EFAULT)); \
})
