PERCPU : __percpu_alloc_mask() can dynamically size percpu_data storage

[Chris Wright]

-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Eric Dumazet <dada1@xxxxxxxxxxxxx>

upstream commit: b3242151906372f30f57feaa43b4cac96a23edb1

Instead of allocating a fix sized array of NR_CPUS pointers for percpu_data,
we can use nr_cpu_ids, which is generally < NR_CPUS.

Signed-off-by: Eric Dumazet <dada1@xxxxxxxxxxxxx>
Cc: Christoph Lameter <clameter@xxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
 include/linux/percpu.h |    2 +-
 mm/allocpercpu.c       |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

This is appropriate for 2.6.24.y

--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -34,7 +34,7 @@
 #ifdef CONFIG_SMP
 
 struct percpu_data {
-	void *ptrs[NR_CPUS];
+	void *ptrs[1];
 };
 
 #define __percpu_disguise(pdata) (struct percpu_data *)~(unsigned long)(pdata)
--- a/mm/allocpercpu.c
+++ b/mm/allocpercpu.c
@@ -98,7 +98,7 @@ EXPORT_SYMBOL_GPL(__percpu_populate_mask
  */
 void *__percpu_alloc_mask(size_t size, gfp_t gfp, cpumask_t *mask)
 {
-	void *pdata = kzalloc(sizeof(struct percpu_data), gfp);
+	void *pdata = kzalloc(nr_cpu_ids * sizeof(void *), gfp);
 	void *__pdata = __percpu_disguise(pdata);
 
 	if (unlikely(!pdata))

-- 
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