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From: Christoph Lameter on 9 Jul 2010 15:20
In pcpu_build_alloc_info() and pcpu_embed_first_chunk(), @dyn_size was
ssize_t, -1 meant auto-size, 0 forced 0 and positive meant minimum
size. There's no use case for forcing 0 and the upcoming early alloc
support always requires non-zero dynamic size. Make @dyn_size always
mean minimum dyn_size.

While at it, make pcpu_build_alloc_info() static which doesn't have
any external caller as suggested by David Rientjes.

Signed-off-by: Tejun Heo <tj(a)kernel.org>
Acked-by: David Rientjes <rientjes(a)google.com>
Signed-off-by: Christoph Lameter <cl(a)linux-foundation.org>

Index: work/include/linux/percpu.h
===================================================================
--- work.orig/include/linux/percpu.h
+++ work/include/linux/percpu.h
@@ -104,16 +104,11 @@ extern struct pcpu_alloc_info * __init p
int nr_units);
extern void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai);

-extern struct pcpu_alloc_info * __init pcpu_build_alloc_info(
- size_t reserved_size, ssize_t dyn_size,
- size_t atom_size,
- pcpu_fc_cpu_distance_fn_t cpu_distance_fn);
-
extern int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
void *base_addr);

#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
-extern int __init pcpu_embed_first_chunk(size_t reserved_size, ssize_t dyn_size,
+extern int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
size_t atom_size,
pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
pcpu_fc_alloc_fn_t alloc_fn,
Index: work/mm/percpu.c
===================================================================
--- work.orig/mm/percpu.c
+++ work/mm/percpu.c
@@ -1013,20 +1013,6 @@ phys_addr_t per_cpu_ptr_to_phys(void *ad
return page_to_phys(pcpu_addr_to_page(addr));
}

-static inline size_t pcpu_calc_fc_sizes(size_t static_size,
- size_t reserved_size,
- ssize_t *dyn_sizep)
-{
- size_t size_sum;
-
- size_sum = PFN_ALIGN(static_size + reserved_size +
- (*dyn_sizep >= 0 ? *dyn_sizep : 0));
- if (*dyn_sizep != 0)
- *dyn_sizep = size_sum - static_size - reserved_size;
-
- return size_sum;
-}
-
/**
* pcpu_alloc_alloc_info - allocate percpu allocation info
* @nr_groups: the number of groups
@@ -1085,7 +1071,7 @@ void __init pcpu_free_alloc_info(struct
/**
* pcpu_build_alloc_info - build alloc_info considering distances between CPUs
* @reserved_size: the size of reserved percpu area in bytes
- * @dyn_size: free size for dynamic allocation in bytes, -1 for auto
+ * @dyn_size: minimum free size for dynamic allocation in bytes
* @atom_size: allocation atom size
* @cpu_distance_fn: callback to determine distance between cpus, optional
*
@@ -1103,8 +1089,8 @@ void __init pcpu_free_alloc_info(struct
* On success, pointer to the new allocation_info is returned. On
* failure, ERR_PTR value is returned.
*/
-struct pcpu_alloc_info * __init pcpu_build_alloc_info(
- size_t reserved_size, ssize_t dyn_size,
+static struct pcpu_alloc_info * __init pcpu_build_alloc_info(
+ size_t reserved_size, size_t dyn_size,
size_t atom_size,
pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
{
@@ -1123,13 +1109,15 @@ struct pcpu_alloc_info * __init pcpu_bui
memset(group_map, 0, sizeof(group_map));
memset(group_cnt, 0, sizeof(group_cnt));

+ size_sum = PFN_ALIGN(static_size + reserved_size + dyn_size);
+ dyn_size = size_sum - static_size - reserved_size;
+
/*
* Determine min_unit_size, alloc_size and max_upa such that
* alloc_size is multiple of atom_size and is the smallest
* which can accomodate 4k aligned segments which are equal to
* or larger than min_unit_size.
*/
- size_sum = pcpu_calc_fc_sizes(static_size, reserved_size, &dyn_size);
min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);

alloc_size = roundup(min_unit_size, atom_size);
@@ -1532,7 +1520,7 @@ early_param("percpu_alloc", percpu_alloc
/**
* pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
* @reserved_size: the size of reserved percpu area in bytes
- * @dyn_size: free size for dynamic allocation in bytes, -1 for auto
+ * @dyn_size: minimum free size for dynamic allocation in bytes
* @atom_size: allocation atom size
* @cpu_distance_fn: callback to determine distance between cpus, optional
* @alloc_fn: function to allocate percpu page
@@ -1553,10 +1541,7 @@ early_param("percpu_alloc", percpu_alloc
* vmalloc space is not orders of magnitude larger than distances
* between node memory addresses (ie. 32bit NUMA machines).
*
- * When @dyn_size is positive, dynamic area might be larger than
- * specified to fill page alignment. When @dyn_size is auto,
- * @dyn_size is just big enough to fill page alignment after static
- * and reserved areas.
+ * @dyn_size specifies the minimum dynamic area size.
*
* If the needed size is smaller than the minimum or specified unit
* size, the leftover is returned using @free_fn.
@@ -1564,7 +1549,7 @@ early_param("percpu_alloc", percpu_alloc
* RETURNS:
* 0 on success, -errno on failure.
*/
-int __init pcpu_embed_first_chunk(size_t reserved_size, ssize_t dyn_size,
+int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
size_t atom_size,
pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
pcpu_fc_alloc_fn_t alloc_fn,
@@ -1695,7 +1680,7 @@ int __init pcpu_page_first_chunk(size_t

snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);

- ai = pcpu_build_alloc_info(reserved_size, -1, PAGE_SIZE, NULL);
+ ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
if (IS_ERR(ai))
return PTR_ERR(ai);
BUG_ON(ai->nr_groups != 1);

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Prev: [S+Q2 08/19] slub: Use kmem_cache flags to detect if slab is in debugging mode.
Next: [S+Q2 14/19] slub: Move gfpflag masking out of the hotpath