cpumask: Provide a generic set of CPUMASK_ALLOC macros

  * Provide a generic set of CPUMASK_ALLOC macros patterned after the
    SCHED_CPUMASK_ALLOC macros.  This is used where multiple cpumask_t
    variables are declared on the stack to reduce the amount of stack
    space required.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 2dbd9a287e77..72f9c32c12b0 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -75,6 +75,17 @@
  * CPU_MASK_NONE                        Initializer - no bits set
  * unsigned long *cpus_addr(mask)       Array of unsigned long's in mask
  *
+ *if NR_CPUS > BITS_PER_LONG
+ *   CPUMASK_ALLOC(m)                   Declares and allocates struct m *m =
+ *                                         (struct m *)kmalloc(sizeof(*m), ...)
+ *   CPUMASK_FREE(m)                    Macro for kfree(v)
+ *else
+ *   CPUMASK_ALLOC(m)                   Declares struct m _m, *m = &_m
+ *   CPUMASK_FREE(m)                    Nop
+ *endif
+ *   CPUMASK_VAR(v, m)                  Declares cpumask_t *v =
+ *                                              m + offset(struct m, v)
+ *
  * int cpumask_scnprintf(buf, len, mask) Format cpumask for printing
  * int cpumask_parse_user(ubuf, ulen, mask)     Parse ascii string as cpumask
  * int cpulist_scnprintf(buf, len, mask) Format cpumask as list for printing
@@ -311,6 +322,16 @@ extern cpumask_t cpu_mask_all;
 
 #define cpus_addr(src) ((src).bits)
 
+#if NR_CPUS > BITS_PER_LONG
+#define CPUMASK_ALLOC(m)        struct m *m = kmalloc(sizeof(*m), GFP_KERNEL)
+#define CPUMASK_FREE(m)         kfree(m)
+#else
+#define CPUMASK_ALLOC(m)        struct allmasks _m, *m = &_m
+#define CPUMASK_FREE(m)
+#endif
+#define CPUMASK_VAR(v, m)       cpumask_t *v = (cpumask_t *)            \
+                                ((unsigned long)(m) + offsetof(struct m, v))
+
 #define cpumask_scnprintf(buf, len, src) \
                         __cpumask_scnprintf((buf), (len), &(src), NR_CPUS)
 static inline int __cpumask_scnprintf(char *buf, int len,