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Subject[PATCH] add likely around access_ok for uaccess
Hi,

while trying to figure out why sysv msg is around 30% slower than pipes
for data transfers I noticed that gcc's autodetection (3.2.2) guesses
the "if(access_ok())" tests in uaccess.h wrong and puts the error memset
into the direct path and the copy out of line.

The attached patch adds likely to the tests - any objections? What about
the archs except i386?

--
Manfred
--- 2.6/include/asm-i386/uaccess.h 2003-09-12 21:53:58.000000000 +0200
+++ build-2.6/include/asm-i386/uaccess.h 2003-09-14 12:56:19.000000000 +0200
@@ -300,7 +300,7 @@
long __pu_err = -EFAULT; \
__typeof__(*(ptr)) *__pu_addr = (ptr); \
might_sleep(); \
- if (access_ok(VERIFY_WRITE,__pu_addr,size)) \
+ if (likely(access_ok(VERIFY_WRITE,__pu_addr,size))) \
__put_user_size((x),__pu_addr,(size),__pu_err,-EFAULT); \
__pu_err; \
})
@@ -510,7 +510,7 @@
direct_copy_to_user(void __user *to, const void *from, unsigned long n)
{
might_sleep();
- if (access_ok(VERIFY_WRITE, to, n))
+ if (likely(access_ok(VERIFY_WRITE, to, n)))
n = __direct_copy_to_user(to, from, n);
return n;
}
@@ -535,7 +535,7 @@
direct_copy_from_user(void *to, const void __user *from, unsigned long n)
{
might_sleep();
- if (access_ok(VERIFY_READ, from, n))
+ if (likely(access_ok(VERIFY_READ, from, n)))
n = __direct_copy_from_user(to, from, n);
else
memset(to, 0, n);
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