Re: why "probe_kernel_address()", not "probe_user_address()"?

From: Andrew Morton
Date: Sat Oct 28 2006 - 12:33:06 EST


On Sat, 28 Oct 2006 11:56:24 -0400 (EDT)
"Robert P. J. Day" <rpjday@xxxxxxxxxxxxxx> wrote:

>
> it seems odd that the purpose of the "probe_kernel_address()" macro
> is, in fact, to probe a *user* address (from linux/uaccess.h):
>
> #define probe_kernel_address(addr, retval) \
> ({ \
> long ret; \
> \
> inc_preempt_count(); \
> ret = __get_user(retval, addr); \
> dec_preempt_count(); \
> ret; \
> })
>
> given that that routine is referenced only 5 places in the entire
> source tree, wouldn't it be more meaningful to use a more appropriate
> name?
>

You'll notice that all callers are indeed probing kernel addresses. The
function _could_ be used for user addresses and could perhaps be called
probe_address().

One of the reasons this wrapper exists is to communicate that the
__get_user() it is in fact not being used to access user memory.
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