Messages in this thread | | | Date | Mon, 29 Mar 2004 17:46:37 -0800 | From | Paul Jackson <> | Subject | Re: [PATCH] mask ADT: bitmap and bitop tweaks [1/22] |
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> akpm, this is needed for mainline.
How urgent to you consider this fix (masking unused bits in the arithmetic (single unsigned long word) cpumask implementation?
So far as I know, the only way to get high bits set with correct invocations is by using cpus_complement(), which I don't see anyone doing.
So I believe that this patch fixes latent bugs, not current bugs.
And it would be my preference (not surprisingly) to fix this in a way that is consistent with my mask ADT proposal (avoid setting unused bits on proper calls; don't filter on Boolean/scalar predicate evaluations):
+#if NR_CPUS % BITS_PER_LONG +#define __CPU_VALID_MASK__ (~((1UL<< (NR_CPUS%BITS_PER_LONG) - 1)) +#else +#define __CPU_VALID_MASK__ (~0UL) +#endif
-#define cpus_complement(map) do { map = ~(map); } while (0) +#define cpus_complement(map) \ + do { map = ~(map) & __CPU_VALID_MASK__; } while (0)
_instead_ of changing the several other macros to follow the bitmap convention (let the unused bits remain dont-care, until resolving a Boolean or scalar predicate).
-- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson <pj@sgi.com> 1.650.933.1373 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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