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Subject[PATCH 27/35] cpumask: to_cpumask()
There are times when we really want a static cpumask.  Yet we don't
want to expose the struct cpumask definition, to avoid casual on-stack
usage and assignment.

So this macro allows you to do DECLARE_BITMAP(map, CONFIG_NR_CPUS); then use
to_cpumask() to turn it into a cpumask as needed.

Ugly? Yes, but as we move to fewer static cpumasks these calls vanish.

From: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
---
include/linux/cpumask.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)
--- linux-2.6.28.orig/include/linux/cpumask.h
+++ linux-2.6.28/include/linux/cpumask.h
@@ -57,6 +57,9 @@
* CPU_MASK_NONE Initializer - no bits set
* unsigned long *cpumask_bits(mask) Array of unsigned long's in mask
*
+ * struct cpumask *to_cpumask(const unsigned long[])
+ * Convert a bitmap to a cpumask.
+ *
* ------------------------------------------------------------------------
*
* int cpumask_scnprintf(buf, len, mask) Format cpumask for printing
@@ -362,6 +365,17 @@ static inline void cpumask_copy(struct c
#define cpumask_any(srcp) cpumask_first(srcp)
#define cpumask_any_and(mask1, mask2) cpumask_first_and((mask1), (mask2))

+/* Used for static bitmaps of CONFIG_NR_CPUS bits. Must be a constant to use
+ * as an initializer. */
+#define to_cpumask(bitmap) \
+ ((struct cpumask *)(1 ? (bitmap) \
+ : (void *)sizeof(__check_is_bitmap(bitmap))))
+
+static inline int __check_is_bitmap(const unsigned long *bitmap)
+{
+ return 1;
+}
+
/*
* Special-case data structure for "single bit set only" constant CPU masks.
*
--


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