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Subject[PATCH 1/3] percpu: use ZERO_SIZE_PTR / ZERO_OR_NULL_PTR
Date
Fix pcpu_alloc() to return ZERO_SIZE_PTR if requested size is 0;
fix free_percpu() to check passed pointer with ZERO_OR_NULL_PTR.

Signed-off-by: Dmitry Antipov <dmitry.antipov@linaro.org>
---
mm/percpu.c | 16 +++++++++++-----
1 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index f47af91..e903a19 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -702,7 +702,8 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
* Does GFP_KERNEL allocation.
*
* RETURNS:
- * Percpu pointer to the allocated area on success, NULL on failure.
+ * ZERO_SIZE_PTR if @size is zero, percpu pointer to the
+ * allocated area on success or NULL on failure.
*/
static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved)
{
@@ -713,7 +714,10 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved)
unsigned long flags;
void __percpu *ptr;

- if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
+ if (unlikely(!size))
+ return ZERO_SIZE_PTR;
+
+ if (unlikely(size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
WARN(true, "illegal size (%zu) or align (%zu) for "
"percpu allocation\n", size, align);
return NULL;
@@ -834,7 +838,8 @@ fail_unlock_mutex:
* Does GFP_KERNEL allocation.
*
* RETURNS:
- * Percpu pointer to the allocated area on success, NULL on failure.
+ * ZERO_SIZE_PTR if @size is zero, percpu pointer to the
+ * allocated area on success, NULL on failure.
*/
void __percpu *__alloc_percpu(size_t size, size_t align)
{
@@ -856,7 +861,8 @@ EXPORT_SYMBOL_GPL(__alloc_percpu);
* Does GFP_KERNEL allocation.
*
* RETURNS:
- * Percpu pointer to the allocated area on success, NULL on failure.
+ * ZERO_SIZE_PTR if @size is zero, percpu pointer to the
+ * allocated area on success or NULL on failure.
*/
void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
{
@@ -917,7 +923,7 @@ void free_percpu(void __percpu *ptr)
unsigned long flags;
int off;

- if (!ptr)
+ if (unlikely(ZERO_OR_NULL_PTR(ptr)))
return;

kmemleak_free_percpu(ptr);
--
1.7.7.6


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