Re: [PATCH] Fix cpu iterator on empty bitmask

[William Lee Irwin III <wli@holomorphy.com>]

Rusty wrote:
>> Agreed, I'm pretty sure Paul's work doesn't make this mistake, but this
>> is a trivial patch for a real big which is causing oopses today.
>> Linus, please apply...

On Tue, Apr 27, 2004 at 06:31:35PM -0700, Paul Jackson wrote:
> agreed

Eh? Why are you now suddenly changing your tune from when I wrote a fix
for this and others just 10 days ago? The remainder of the missing fixes
below.


-- wli


Index: wli-2.6.5-mm6/include/asm-generic/cpumask_arith.h
===================================================================
--- wli-2.6.5-mm6.orig/include/asm-generic/cpumask_arith.h	2004-04-03 19:37:37.000000000 -0800
+++ wli-2.6.5-mm6/include/asm-generic/cpumask_arith.h	2004-04-17 19:11:53.000000000 -0700
@@ -15,17 +15,17 @@
 #define cpus_or(dst,src1,src2)		do { dst = (src1) | (src2); } while (0)
 #define cpus_clear(map)			do { map = 0; } while (0)
 #define cpus_complement(map)		do { map = ~(map); } while (0)
-#define cpus_equal(map1, map2)		((map1) == (map2))
-#define cpus_empty(map)			((map) == 0)
+#define cpus_equal(map1, map2)		(!(((map1) ^ (map2)) & CPU_MASK_ALL))
+#define cpus_empty(map)			(!((map) & CPU_MASK_ALL))
 #define cpus_addr(map)			(&(map))
 
 #if BITS_PER_LONG == 32
-#define cpus_weight(map)		hweight32(map)
+#define cpus_weight(map)		hweight32((map) & CPU_MASK_ALL)
 #elif BITS_PER_LONG == 64
-#define cpus_weight(map)		hweight64(map)
+#define cpus_weight(map)		hweight64((map) & CPU_MASK_ALL)
 #endif
 
-#define cpus_shift_right(dst, src, n)	do { dst = (src) >> (n); } while (0)
+#define cpus_shift_right(dst, src, n)	do { dst = ((src) >> (n)) & CPU_MASK_ALL; } while (0)
 #define cpus_shift_left(dst, src, n)	do { dst = (src) << (n); } while (0)
 
 #define any_online_cpu(map)			\
@@ -39,11 +39,15 @@
 #define CPU_MASK_NONE	((cpumask_t)0)
 
 /* only ever use this for things that are _never_ used on large boxen */
-#define cpus_coerce(map)		((unsigned long)(map))
+#define cpus_coerce(map)		((unsigned long)(map) & CPU_MASK_ALL)
 #define cpus_promote(map)		({ map; })
 #define cpumask_of_cpu(cpu)		({ ((cpumask_t)1) << (cpu); })
 
-#define first_cpu(map)			__ffs(map)
 #define next_cpu(cpu, map)		find_next_bit(&(map), NR_CPUS, cpu + 1)
+#define first_cpu(map)						\
+({								\
+	cpumask_t __first_cpu_map__ = (map) & CPU_MASK_ALL;	\
+	__first_cpu_map__ ? __ffs(__first_cpu_map__) : NR_CPUS;	\
+})
 
 #endif /* __ASM_GENERIC_CPUMASK_ARITH_H */