Messages in this thread | | | Subject | Re: [PATCH] bitmap: separate bitmap parsing for user buffer and kernel buffer | From | Andi Kleen <> | Date | 05 Oct 2006 21:57:04 +0200 |
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Andrew Morton <akpm@osdl.org> writes:
> On Wed, 4 Oct 2006 17:56:30 -0700 > Reinette Chatre <reinette.chatre@linux.intel.com> 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.
It is needed on lots of architectures that use separate address spaces like sparc64, m68k, s390 (and on x86 with 4:4 patches)
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