Messages in this thread | | | Date | Sat, 18 Dec 2010 15:47:30 +0100 | From | Tejun Heo <> | Subject | Re: [cpuops cmpxchg double V1 1/4] Generic support for this_cpu_cmpxchg_double |
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Hello, Christoph.
On 12/14/2010 06:48 PM, Christoph Lameter wrote: > +/* > + * cmpxchg_double replaces two adjacent scalars at once. The first parameter > + * passed is a percpu pointer, not a scalar like the other this_cpu > + * operations. This is so because the function operates on two scalars > + * (must be of same size). A truth value is returned to indicate success or > + * failure (since a double register result is difficult to handle). > + * There is very limited hardware support for these operations. So only certain > + * sizes may work. > + */ > +#define __this_cpu_generic_cmpxchg_double(pcp, oval1, oval2, nval1, nval2)
This is ugly. :-( I think we should have made this_cpu_*() ops take pointers from the beginning. Anyways, that's too late, so is it completely impossible to make cmpxchg_double's take a scalar value? It can take the pointer all the same, no?
Thanks.
-- tejun
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