On Mon, Apr 01, 2019 at 10:10:33PM +0200, Rasmus Villemoes wrote: > On 30/03/2019 19.54, Yury Norov wrote: > > Hi Rasmus! > > > >> From: Rasmus Villemoes <[email protected]> > >> Sent: Saturday, March 30, 2019 12:53:51 AM > >> To: Rasmus Villemoes; Andrew Morton; Andy Shevchenko > >> Cc: Yury Norov; [email protected] > >> Subject: [PATCH 2/2] lib/bitmap.c: guard exotic bitmap functions by > >> CONFIG_NUMA > >> > >> The bitmap_remap, _bitremap, _onto and _fold functions are only used, > >> via their node_ wrappers, in mm/mempolicy.c, which is only built for > >> CONFIG_NUMA. The helper bitmap_ord_to_pos used by these functions is > >> global, but its only external caller is node_random() in lib/nodemask.c, > >> which is also guarded by CONFIG_NUMA. > > > > Nice catch. I think you should protect declaration of those functions > > in include/linux/bitmap.h as well. > > Yeah, well, it's not that simple, because one would also need to wrap > the static inline __nodes_onto etc. in ifdefs. Normally, there'd be an > #else branch defining simple static inline replacements that always fail > or return 0, but we can't do that here.
There are enough examples of conditionally defined functions without stubs, I don't see any problem with it. Anyways, if you don't like doing that, moving the code and declarations to new files would help. > So I'd prefer a simple linker > error should any user outside NUMA ever appear. Which I very highly doubt. Linker errors are usually less specific and much longer to obtain at the linker-stage, which is not good. > > I'm concerned about pollution of such a generic portion of code with > > subsystem-related #ifdefs. Would it make more sense to move numa-specific > > stuff to lib/bitmap_numa.c and include/linux/bitmap_numa.h (or *_nodemask.h, > > or whatever)? > > Well, yes, that might be better, but a lot bigger patch. One could also > argue that bitmap.c is _already_ polluted with subsystem specific code > (though not in the form of preprocessor directives). I probably don't understand the argument. If we find bitmap.c polluted, we should try clean it, right?
