Re: [PATCH] bitmap: separate bitmap parsing for user buffer and kernel buffer

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Andrew Morton wrote:
On Wed, 4 Oct 2006 17:56:30 -0700
Reinette Chatre <[email protected]> wrote:

+			if (is_user) {
+				if (__get_user(c, buf++))
+					return -EFAULT;
+			}
+			else
+				c = *buf++;

Is this actually needed?  __get_user(kernel_address) works OK and (believe
it or not, given all the stuff it involves) boils down to a single instruction.		

On some architectures, kernel and user space are separate, overlapping address spaces.

If __bitmap_parse was an inline (and not exported), this would be okay; as it is, you end up doing the test dynamically under all circumstances, even though in most (if not all) cases the address space is know a priori.

	-hpa
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