Re: [PATCH] nodemask_t x86_64 changes [5/7]

[Paul Jackson]

> CPU_MASK_ALL ...

Yup - now you tell me ... ;).

I just got done figuring it out in a slightly variant way ... ('nbits'
is NR_CPUS or similar):

#define MASK_LAST_WORD(nbits)                                           \
(                                                                       \
        ((nbits) % BITS_PER_LONG) ?                                     \
                (1<<((nbits) % BITS_PER_LONG))-1 : ~0UL                 \
)

#define MASK_ALL(nbits)                                                 \
{ {                                                                     \
        [0 ... BITS_TO_LONGS(nbits)-1] = ~0UL,                          \
        [BITS_TO_LONGS(nbits)-1] = MASK_LAST_WORD(nbits)                \
} }

This way overwrites the last word of the mask, first putting ~0UL
in all words, then however many bits are needed in the last word.

Does your way work if NR_CPUS is less than BITS_PER_LONG?
Won't gcc complain upon seeing something like, for say
NR_CPUS = 4 on a 32 bit system:

   { [ 0 ... -1 ] = ~0UL, ~0UL << 28 }

with the errors and warnings:

  error: empty index range in initializer
  warning: excess elements in struct initializer

and shouldn't the last word be inverted: ~(~0UL << NR_CPUS_UNDEF) ?

-- 
                          I won't rest till it's the best ...
                          Programmer, Linux Scalability
                          Paul Jackson <pj@xxxxxxx> 1.650.933.1373
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