linux-kernel - Re: [PATCH] mm, slab: rename kmalloc-node cache to kmalloc-<size>

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Date:   Thu, 9 Feb 2017 10:12:24 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     kbuild test robot <lkp@...el.com>, kbuild-all@...org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        David Rientjes <rientjes@...gle.com>,
        Pekka Enberg <penberg@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        Matthew Wilcox <willy@...ux.intel.com>
Subject: Re: [PATCH] mm, slab: rename kmalloc-node cache to kmalloc-<size>

On 02/08/2017 10:54 PM, Andrew Morton wrote:
> On Wed, 8 Feb 2017 10:12:13 +0100 Vlastimil Babka <vbabka@...e.cz> wrote:
> 
>> Thanks for the fix.
>> 
>> I was going to implement Christoph's suggestion and export the whole structure
>> in mm/slab.h, but gcc was complaining that I'm redefining it, until I created a
>> typedef first. Is it worth the trouble? Below is how it would look like.
>> 
>> ...
>>
>> --- a/mm/slab.h
>> +++ b/mm/slab.h
>> @@ -71,6 +71,13 @@ extern struct list_head slab_caches;
>>  /* The slab cache that manages slab cache information */
>>  extern struct kmem_cache *kmem_cache;
>>  
>> +/* A table of kmalloc cache names and sizes */
>> +typedef struct {
>> +	const char *name;
>> +	unsigned long size;
>> +} kmalloc_info_t;
>> +extern const kmalloc_info_t kmalloc_info[];
> 
> Why is the typedef needed?  Can't we use something like

Duh, right, I can't C. Thanks.

----8<----
>From 15fc08501ddaaf1a6cf2c2d37755c61e1e5c1341 Mon Sep 17 00:00:00 2001
From: Vlastimil Babka <vbabka@...e.cz>
Date: Wed, 8 Feb 2017 11:00:11 +0100
Subject: [PATCH] mm, slab: rename kmalloc-node cache to kmalloc-<size>-fix2

Export the whole kmalloc_info structure instead of just a name accessor,
per Christoph Lameter.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
 mm/slab.c        |  2 +-
 mm/slab.h        |  7 ++++++-
 mm/slab_common.c | 10 +---------
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index ede31b59bb9f..9d66b3d6791e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1294,7 +1294,7 @@ void __init kmem_cache_init(void)
 	 * structures first.  Without this, further allocations will bug.
 	 */
 	kmalloc_caches[INDEX_NODE] = create_kmalloc_cache(
-				get_kmalloc_cache_name(INDEX_NODE),
+				kmalloc_info[INDEX_NODE].name,
 				kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS);
 	slab_state = PARTIAL_NODE;
 	setup_kmalloc_cache_index_table();
diff --git a/mm/slab.h b/mm/slab.h
index 5708c548c6f7..2fa824335a50 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -71,6 +71,12 @@ extern struct list_head slab_caches;
 /* The slab cache that manages slab cache information */
 extern struct kmem_cache *kmem_cache;
 
+/* A table of kmalloc cache names and sizes */
+extern const struct kmalloc_info_struct {
+	const char *name;
+	unsigned long size;
+} kmalloc_info[];
+
 unsigned long calculate_alignment(unsigned long flags,
 		unsigned long align, unsigned long size);
 
@@ -78,7 +84,6 @@ unsigned long calculate_alignment(unsigned long flags,
 /* Kmalloc array related functions */
 void setup_kmalloc_cache_index_table(void);
 void create_kmalloc_caches(unsigned long);
-const char *get_kmalloc_cache_name(int index);
 
 /* Find the kmalloc slab corresponding for a certain size */
 struct kmem_cache *kmalloc_slab(size_t, gfp_t);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 36a8547de699..be5dce23037d 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -917,10 +917,7 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
  * kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is
  * kmalloc-67108864.
  */
-static struct {
-	const char *name;
-	unsigned long size;
-} const kmalloc_info[] __initconst = {
+const struct kmalloc_info_struct kmalloc_info[] __initconst = {
 	{NULL,                      0},		{"kmalloc-96",             96},
 	{"kmalloc-192",           192},		{"kmalloc-8",               8},
 	{"kmalloc-16",             16},		{"kmalloc-32",             32},
@@ -937,11 +934,6 @@ static struct {
 	{"kmalloc-67108864", 67108864}
 };
 
-const char *get_kmalloc_cache_name(int index)
-{
-	return kmalloc_info[index].name;
-}
-
 /*
  * Patch up the size_index table if we have strange large alignment
  * requirements for the kmalloc array. This is only the case for
-- 
2.11.0