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Subject[PATCH 1/4] percpu: replace pcpu_realloc() with pcpu_mem_alloc() and pcpu_mem_free()
Date
Impact: code reorganization for later changes

With static map handling moved to pcpu_split_block(), pcpu_realloc()
only clutters the code and it's also unsuitable for scheduled locking
changes. Implement and use pcpu_mem_alloc/free() instead.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
mm/percpu.c | 85 +++++++++++++++++++++++++++++------------------------------
1 files changed, 42 insertions(+), 43 deletions(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index ef8e169..f1d0e90 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -164,39 +164,41 @@ static bool pcpu_chunk_page_occupied(struct pcpu_chunk *chunk,
}

/**
- * pcpu_realloc - versatile realloc
- * @p: the current pointer (can be NULL for new allocations)
- * @size: the current size in bytes (can be 0 for new allocations)
- * @new_size: the wanted new size in bytes (can be 0 for free)
+ * pcpu_mem_alloc - allocate memory
+ * @size: bytes to allocate
*
- * More robust realloc which can be used to allocate, resize or free a
- * memory area of arbitrary size. If the needed size goes over
- * PAGE_SIZE, kernel VM is used.
+ * Allocate @size bytes. If @size is smaller than PAGE_SIZE,
+ * kzalloc() is used; otherwise, vmalloc() is used. The returned
+ * memory is always zeroed.
*
* RETURNS:
- * The new pointer on success, NULL on failure.
+ * Pointer to the allocated area on success, NULL on failure.
*/
-static void *pcpu_realloc(void *p, size_t size, size_t new_size)
+static void *pcpu_mem_alloc(size_t size)
{
- void *new;
-
- if (new_size <= PAGE_SIZE)
- new = kmalloc(new_size, GFP_KERNEL);
- else
- new = vmalloc(new_size);
- if (new_size && !new)
- return NULL;
-
- memcpy(new, p, min(size, new_size));
- if (new_size > size)
- memset(new + size, 0, new_size - size);
+ if (size <= PAGE_SIZE)
+ return kzalloc(size, GFP_KERNEL);
+ else {
+ void *ptr = vmalloc(size);
+ if (ptr)
+ memset(ptr, 0, size);
+ return ptr;
+ }
+}

+/**
+ * pcpu_mem_free - free memory
+ * @ptr: memory to free
+ * @size: size of the area
+ *
+ * Free @ptr. @ptr should have been allocated using pcpu_mem_alloc().
+ */
+static void pcpu_mem_free(void *ptr, size_t size)
+{
if (size <= PAGE_SIZE)
- kfree(p);
+ kfree(ptr);
else
- vfree(p);
-
- return new;
+ vfree(ptr);
}

/**
@@ -331,29 +333,27 @@ static int pcpu_split_block(struct pcpu_chunk *chunk, int i, int head, int tail)
if (chunk->map_alloc < target) {
int new_alloc;
int *new;
+ size_t size;

new_alloc = PCPU_DFL_MAP_ALLOC;
while (new_alloc < target)
new_alloc *= 2;

- if (chunk->map_alloc < PCPU_DFL_MAP_ALLOC) {
- /*
- * map_alloc smaller than the default size
- * indicates that the chunk is one of the
- * first chunks and still using static map.
- * Allocate a dynamic one and copy.
- */
- new = pcpu_realloc(NULL, 0, new_alloc * sizeof(new[0]));
- if (new)
- memcpy(new, chunk->map,
- chunk->map_alloc * sizeof(new[0]));
- } else
- new = pcpu_realloc(chunk->map,
- chunk->map_alloc * sizeof(new[0]),
- new_alloc * sizeof(new[0]));
+ new = pcpu_mem_alloc(new_alloc * sizeof(new[0]));
if (!new)
return -ENOMEM;

+ size = chunk->map_alloc * sizeof(chunk->map[0]);
+ memcpy(new, chunk->map, size);
+
+ /*
+ * map_alloc < PCPU_DFL_MAP_ALLOC indicates that the
+ * chunk is one of the first chunks and still using
+ * static map.
+ */
+ if (chunk->map_alloc >= PCPU_DFL_MAP_ALLOC)
+ pcpu_mem_free(chunk->map, size);
+
chunk->map_alloc = new_alloc;
chunk->map = new;
}
@@ -696,7 +696,7 @@ static void free_pcpu_chunk(struct pcpu_chunk *chunk)
return;
if (chunk->vm)
free_vm_area(chunk->vm);
- pcpu_realloc(chunk->map, chunk->map_alloc * sizeof(chunk->map[0]), 0);
+ pcpu_mem_free(chunk->map, chunk->map_alloc * sizeof(chunk->map[0]));
kfree(chunk);
}

@@ -708,8 +708,7 @@ static struct pcpu_chunk *alloc_pcpu_chunk(void)
if (!chunk)
return NULL;

- chunk->map = pcpu_realloc(NULL, 0,
- PCPU_DFL_MAP_ALLOC * sizeof(chunk->map[0]));
+ chunk->map = pcpu_mem_alloc(PCPU_DFL_MAP_ALLOC * sizeof(chunk->map[0]));
chunk->map_alloc = PCPU_DFL_MAP_ALLOC;
chunk->map[chunk->map_used++] = pcpu_unit_size;
chunk->page = chunk->page_ar;
--
1.6.0.2


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