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Subject[PATCH 7/8] cpumask: Provide a generic set of CPUMASK_ALLOC macros, FIXUP
  * Rename CPUMASK_VAR --> CPUMASK_PTR (and simplify)

* Fix a semantic error in CPUMASK_ALLOC

* Add a bit of commentry to cpumask.h

Based on linux-2.6.tip/master with the following commit:

commit 77586c2bdad0798cb24e35de5a878e7c6b200574
Author: Mike Travis <travis@sgi.com> 2008-07-15 14:14:37
Committer: Ingo Molnar <mingo@elte.hu> 2008-07-18 13:03:00
Parent: 77586c2bdad0798cb24e35de5a878e7c6b200574 (cpumask: Provide a generic set of CPUMASK_ALLOC macros)
Child: 06f8d00e9eecb738c99b737ac38a585ea7583ad5 (cpumask: Optimize cpumask_of_cpu in lib/smp_processor_id.c, fix)
Child: 32650cb6a8665a7635d025e52d9bf1905981ed11 (Merge branch 'cpus4096')
Branches: -, devel, remotes/tip/cpus4096, remotes/tip/master, tip-latest

cpumask: Provide a generic set of CPUMASK_ALLOC macros


Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Bert Wesarg <bert.wesarg@googlemail.com>
---
include/linux/cpumask.h | 33 ++++++++++++++++++++++++++-------
1 file changed, 26 insertions(+), 7 deletions(-)

--- linux-2.6.tip.orig/include/linux/cpumask.h
+++ linux-2.6.tip/include/linux/cpumask.h
@@ -75,16 +75,36 @@
* CPU_MASK_NONE Initializer - no bits set
* unsigned long *cpus_addr(mask) Array of unsigned long's in mask
*
+ * CPUMASK_ALLOC kmalloc's a structure that is a composite of many cpumask_t
+ * variables, and CPUMASK_PTR provides pointers to each field.
+ *
+ * The structure should be defined something like this:
+ * struct my_cpumasks {
+ * cpumask_t mask1;
+ * cpumask_t mask2;
+ * };
+ *
+ * Usage is then:
+ * CPUMASK_ALLOC(my_cpumasks);
+ * CPUMASK_PTR(mask1, my_cpumasks);
+ * CPUMASK_PTR(mask2, my_cpumasks);
+ *
+ * --- DO NOT reference cpumask_t pointers until this check ---
+ * if (my_cpumasks == NULL)
+ * "kmalloc failed"...
+ *
+ * References are now pointers to the cpumask_t variables (*mask1, ...)
+ *
*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)
+ * kmalloc(sizeof(*m), GFP_KERNEL)
+ * CPUMASK_FREE(m) Macro for kfree(m)
*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)
+ * CPUMASK_PTR(v, m) Declares cpumask_t *v = &(m->v)
+ * ------------------------------------------------------------------------
*
* int cpumask_scnprintf(buf, len, mask) Format cpumask for printing
* int cpumask_parse_user(ubuf, ulen, mask) Parse ascii string as cpumask
@@ -326,11 +346,10 @@ extern cpumask_t cpu_mask_all;
#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_ALLOC(m) struct m _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_PTR(v, m) cpumask_t *v = &(m->v)

#define cpumask_scnprintf(buf, len, src) \
__cpumask_scnprintf((buf), (len), &(src), NR_CPUS)
--


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