Re: [patch 1/6] mempolicy: convert MPOL constants to enum

From: Paul Jackson
Date: Mon Feb 25 2008 - 22:21:39 EST


David wrote:

+enum {
+ MPOL_DEFAULT,
+ MPOL_PREFERRED,
+ MPOL_BIND,
+ MPOL_INTERLEAVE,
+ MPOL_MAX, /* always last member of enum */

Aren't the values that these constants take part of the
user visible kernel API?

In other words, if someone added another MPOL_* in the middle
of this enum, it would break mbind/set_mempolicy/get_mempolicy
users, right:

+enum {
+ MPOL_DEFAULT,
+ MPOL_PREFERRED,
+ MPOL_YET_ANOTHER_FLAG, /* <== added flag ... oops */
+ MPOL_BIND,
+ MPOL_INTERLEAVE,
+ MPOL_MAX, /* always last member of enum */

I'm thinking that we should still specify the specific value
of each of these flags, by way of documenting these necessary
values, as in:

+enum {
+ MPOL_DEFAULT = 0,
+ MPOL_PREFERRED = 1,
+ MPOL_BIND = 2,
+ MPOL_INTERLEAVE = 3,
+ MPOL_MAX, /* always last member of enum */


--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <pj@xxxxxxx> 1.940.382.4214
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