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Commit 7be75853 authored by Rusty Russell's avatar Rusty Russell
Browse files

cpumask: Use all NR_CPUS bits unless CONFIG_CPUMASK_OFFSTACK 



Impact: futureproof as we convert more code to new APIs

The old cpumask operators treat all NR_CPUS bits as relevent, the new
ones use nr_cpumask_bits.  For large NR_CPUS and small nr_cpu_ids, this
makes a difference.

However, mixing the two can cause problems with undefined bits.  An
arch which sets CONFIG_CPUMASK_OFFSTACK should have converted across
to the new operators, so it's safe in that case.

(Thanks to Stephen Rothwell for bisecting the initial unused-bits bug,
and Mike Travis for this solution).

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Cc: Mike Travis <travis@sgi.com>
parent f0b848ce

include/linux/cpumask.h

+7 −4
Original line number Diff line number Diff line
@@ -510,9 +510,6 @@ extern cpumask_t cpu_active_map; 
	[BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD	\

}



/* This produces more efficient code. */

#define nr_cpumask_bits	NR_CPUS



#else /* NR_CPUS > BITS_PER_LONG */



#define CPU_BITS_ALL						\
@@ -520,9 +517,15 @@ extern cpumask_t cpu_active_map; 
	[0 ... BITS_TO_LONGS(NR_CPUS)-2] = ~0UL,		\

	[BITS_TO_LONGS(NR_CPUS)-1] = CPU_MASK_LAST_WORD		\

}

#endif /* NR_CPUS > BITS_PER_LONG */



#ifdef CONFIG_CPUMASK_OFFSTACK

/* Assuming NR_CPUS is huge, a runtime limit is more efficient.  Also,

 * not all bits may be allocated. */

#define nr_cpumask_bits	nr_cpu_ids

#endif /* NR_CPUS > BITS_PER_LONG */

#else

#define nr_cpumask_bits	NR_CPUS

#endif



/* verify cpu argument to cpumask_* operators */

static inline unsigned int cpumask_check(unsigned int cpu)