Re: [PATCH] x86 Topology cpu_to_node parameter check

[Mathieu Desnoyers]

* Steven Rostedt (rostedt@xxxxxxxxxxx) wrote:
> 
> On Fri, 3 Oct 2008, Mathieu Desnoyers wrote:
> > 
> > That's how I did it first, but then I looked at asm-generic/topology.h
> > and have seen it uses #defines. Should we change them too ?
> > 
> 
> The old way of doing this is with defines. But all new code should be 
> static inline functions when feasible. This way we can get typechecking 
> on the parameters even when the configuration is disabled.
> 
> Even if the rest of the file uses defines, the new code should be
> static inlines. Eventually, even the old defines will be converted.
> 
> -- Steve
> 

Argh, I think topology.h is utterly broken :-(

Have you noticed the subtile interaction between the

include/asm-x86/topology.h :

#define numa_node_id()          0
#define cpu_to_node(cpu)        0
#define early_cpu_to_node(cpu)  0
...
#include <asm-generic/topology.h>


and
include/asm-generic/topology.h :
#ifndef cpu_to_node
#define cpu_to_node(cpu)        ((void)(cpu),0)
#endif

If any architecture decide for some reason to use a static inline rather
than a define, as currently done with node_to_first_cpu :

include/asm-x86/topology.h :
static inline int node_to_first_cpu(int node)
{
        return first_cpu(cpu_online_map);
}
...
#include <asm-generic/topology.h>

include/asm-generic/topology.h :
#ifndef node_to_first_cpu
#define node_to_first_cpu(node) ((void)(node),0)
#endif

(which will override the static inline !)

It results in an override of the arch-specific version. Nice eh ?

Mathieu

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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