[PATCH RFC 2/8] mm/slab: change sheaf_capacity type to unsigned short

["Harry Yoo (Oracle)" <harry@kernel.org>]

Change struct kmem_cache.sheaf_capacity and the matching
kmem_cache_args field from unsigned int to unsigned short, so that
we can add a new field later without growing the struct size.
unsigned short is a reasonable size for any realistic configurations.

Signed-off-by: Harry Yoo (Oracle) <harry@kernel.org>
---
 include/linux/slab.h         |  8 ++++----
 mm/slab.h                    |  2 +-
 mm/slub.c                    | 34 +++++++++++++++++-----------------
 tools/include/linux/slab.h   | 14 +++++++-------
 tools/testing/shared/linux.c |  4 ++--
 5 files changed, 31 insertions(+), 31 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 2b5ab488e96b..6f023f04763a 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -371,7 +371,7 @@ struct kmem_cache_args {
 	 *
 	 * %0 means no sheaves will be created.
 	 */
-	unsigned int sheaf_capacity;
+	unsigned short sheaf_capacity;
 };
 
 struct kmem_cache *__kmem_cache_create_args(const char *name,
@@ -828,10 +828,10 @@ void *kmem_cache_alloc_node_noprof(struct kmem_cache *s, gfp_t flags,
 #define kmem_cache_alloc_node(...)	alloc_hooks(kmem_cache_alloc_node_noprof(__VA_ARGS__))
 
 struct slab_sheaf *
-kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size);
+kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned short size);
 
 int kmem_cache_refill_sheaf(struct kmem_cache *s, gfp_t gfp,
-		struct slab_sheaf **sheafp, unsigned int size);
+		struct slab_sheaf **sheafp, unsigned short size);
 
 void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp,
 				       struct slab_sheaf *sheaf);
@@ -841,7 +841,7 @@ void *kmem_cache_alloc_from_sheaf_noprof(struct kmem_cache *cachep, gfp_t gfp,
 #define kmem_cache_alloc_from_sheaf(...)	\
 			alloc_hooks(kmem_cache_alloc_from_sheaf_noprof(__VA_ARGS__))
 
-unsigned int kmem_cache_sheaf_size(struct slab_sheaf *sheaf);
+unsigned short kmem_cache_sheaf_size(struct slab_sheaf *sheaf);
 
 /*
  * These macros allow declaring a kmem_buckets * parameter alongside size, which
diff --git a/mm/slab.h b/mm/slab.h
index bf2f87acf5e3..dfbe73011cb8 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -204,7 +204,7 @@ struct kmem_cache {
 	unsigned int object_size;	/* Object size without metadata */
 	struct reciprocal_value reciprocal_size;
 	unsigned int offset;		/* Free pointer offset */
-	unsigned int sheaf_capacity;
+	unsigned short sheaf_capacity;
 	struct kmem_cache_order_objects oo;
 
 	/* Allocation and freeing of slabs */
diff --git a/mm/slub.c b/mm/slub.c
index 75281eb802de..a1974523bba9 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -418,11 +418,11 @@ struct slab_sheaf {
 		struct list_head barn_list;
 		/* only used for prefilled sheafs */
 		struct {
-			unsigned int capacity;
+			unsigned short capacity;
 			bool pfmemalloc;
 		};
 	};
-	unsigned int size;
+	unsigned short size;
 	int node; /* only used for rcu_sheaf */
 	void *objects[];
 };
@@ -2756,7 +2756,7 @@ static inline void *setup_object(struct kmem_cache *s, void *object)
 }
 
 static struct slab_sheaf *__alloc_empty_sheaf(struct kmem_cache *s, gfp_t gfp,
-					      unsigned int capacity)
+					      unsigned short capacity)
 {
 	struct slab_sheaf *sheaf;
 	size_t sheaf_size;
@@ -2854,10 +2854,10 @@ static void __kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p);
  *
  * Returns how many objects are remaining to be flushed
  */
-static unsigned int __sheaf_flush_main_batch(struct kmem_cache *s)
+static unsigned short __sheaf_flush_main_batch(struct kmem_cache *s)
 {
 	struct slub_percpu_sheaves *pcs;
-	unsigned int batch, remaining;
+	unsigned short batch, remaining;
 	void *objects[PCS_BATCH_MAX];
 	struct slab_sheaf *sheaf;
 
@@ -2884,7 +2884,7 @@ static unsigned int __sheaf_flush_main_batch(struct kmem_cache *s)
 
 static void sheaf_flush_main(struct kmem_cache *s)
 {
-	unsigned int remaining;
+	unsigned short remaining;
 
 	do {
 		local_lock(&s->cpu_sheaves->lock);
@@ -2899,7 +2899,7 @@ static void sheaf_flush_main(struct kmem_cache *s)
  */
 static bool sheaf_try_flush_main(struct kmem_cache *s)
 {
-	unsigned int remaining;
+	unsigned short remaining;
 	bool ret = false;
 
 	do {
@@ -4849,7 +4849,7 @@ unsigned int alloc_from_pcs_bulk(struct kmem_cache *s, gfp_t gfp, size_t size,
 do_alloc:
 
 	main = pcs->main;
-	batch = min(size, main->size);
+	batch = min_t(size_t, size, main->size);
 
 	main->size -= batch;
 	memcpy(p, main->objects + main->size, batch * sizeof(void *));
@@ -5004,7 +5004,7 @@ static int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags,
  * return NULL if sheaf allocation or prefilling failed
  */
 struct slab_sheaf *
-kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size)
+kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned short size)
 {
 	struct slub_percpu_sheaves *pcs;
 	struct slab_sheaf *sheaf = NULL;
@@ -5146,7 +5146,7 @@ void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp,
  * In practice we always refill to full sheaf's capacity.
  */
 int kmem_cache_refill_sheaf(struct kmem_cache *s, gfp_t gfp,
-			    struct slab_sheaf **sheafp, unsigned int size)
+			    struct slab_sheaf **sheafp, unsigned short size)
 {
 	struct slab_sheaf *sheaf;
 
@@ -5225,7 +5225,7 @@ kmem_cache_alloc_from_sheaf_noprof(struct kmem_cache *s, gfp_t gfp,
 	return ret;
 }
 
-unsigned int kmem_cache_sheaf_size(struct slab_sheaf *sheaf)
+unsigned short kmem_cache_sheaf_size(struct slab_sheaf *sheaf)
 {
 	return sheaf->size;
 }
@@ -6172,7 +6172,7 @@ static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p)
 
 do_free:
 	main = pcs->main;
-	batch = min(size, s->sheaf_capacity - main->size);
+	batch = min_t(size_t, size, s->sheaf_capacity - main->size);
 
 	memcpy(main->objects + main->size, p, batch * sizeof(void *));
 	main->size += batch;
@@ -7759,11 +7759,11 @@ static int init_kmem_cache_nodes(struct kmem_cache *s)
 	return 1;
 }
 
-static unsigned int calculate_sheaf_capacity(struct kmem_cache *s,
-					     struct kmem_cache_args *args)
+static unsigned short calculate_sheaf_capacity(struct kmem_cache *s,
+					       struct kmem_cache_args *args)
 
 {
-	unsigned int capacity;
+	unsigned short capacity;
 	size_t size;
 
 
@@ -8466,7 +8466,7 @@ static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache)
 static void __init bootstrap_cache_sheaves(struct kmem_cache *s)
 {
 	struct kmem_cache_args empty_args = {};
-	unsigned int capacity;
+	unsigned short capacity;
 	bool failed = false;
 	int node, cpu;
 
@@ -9091,7 +9091,7 @@ SLAB_ATTR_RO(order);
 
 static ssize_t sheaf_capacity_show(struct kmem_cache *s, char *buf)
 {
-	return sysfs_emit(buf, "%u\n", s->sheaf_capacity);
+	return sysfs_emit(buf, "%hu\n", s->sheaf_capacity);
 }
 SLAB_ATTR_RO(sheaf_capacity);
 
diff --git a/tools/include/linux/slab.h b/tools/include/linux/slab.h
index 6d8e9413d5a4..76d0b9da6cfe 100644
--- a/tools/include/linux/slab.h
+++ b/tools/include/linux/slab.h
@@ -47,7 +47,7 @@ struct kmem_cache {
 	pthread_mutex_t lock;
 	unsigned int size;
 	unsigned int align;
-	unsigned int sheaf_capacity;
+	unsigned short sheaf_capacity;
 	int nr_objs;
 	void *objs;
 	void (*ctor)(void *);
@@ -70,7 +70,7 @@ struct kmem_cache_args {
 	/**
 	 * @sheaf_capacity: The maximum size of the sheaf.
 	 */
-	unsigned int sheaf_capacity;
+	unsigned short sheaf_capacity;
 	/**
 	 * @useroffset: Usercopy region offset.
 	 *
@@ -127,10 +127,10 @@ struct slab_sheaf {
 	union {
 		struct list_head barn_list;
 		/* only used for prefilled sheafs */
-		unsigned int capacity;
+		unsigned short capacity;
 	};
 	struct kmem_cache *cache;
-	unsigned int size;
+	unsigned short size;
 	int node; /* only used for rcu_sheaf */
 	void *objects[];
 };
@@ -186,7 +186,7 @@ void kmem_cache_free_bulk(struct kmem_cache *cachep, size_t size, void **list);
 int kmem_cache_alloc_bulk(struct kmem_cache *cachep, gfp_t gfp, size_t size,
 			  void **list);
 struct slab_sheaf *
-kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size);
+kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned short size);
 
 void *
 kmem_cache_alloc_from_sheaf(struct kmem_cache *s, gfp_t gfp,
@@ -195,9 +195,9 @@ kmem_cache_alloc_from_sheaf(struct kmem_cache *s, gfp_t gfp,
 void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp,
 		struct slab_sheaf *sheaf);
 int kmem_cache_refill_sheaf(struct kmem_cache *s, gfp_t gfp,
-		struct slab_sheaf **sheafp, unsigned int size);
+		struct slab_sheaf **sheafp, unsigned short size);
 
-static inline unsigned int kmem_cache_sheaf_size(struct slab_sheaf *sheaf)
+static inline unsigned short kmem_cache_sheaf_size(struct slab_sheaf *sheaf)
 {
 	return sheaf->size;
 }
diff --git a/tools/testing/shared/linux.c b/tools/testing/shared/linux.c
index 8c7257155958..2da3a6617d87 100644
--- a/tools/testing/shared/linux.c
+++ b/tools/testing/shared/linux.c
@@ -252,7 +252,7 @@ __kmem_cache_create_args(const char *name, unsigned int size,
 }
 
 struct slab_sheaf *
-kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size)
+kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned short size)
 {
 	struct slab_sheaf *sheaf;
 	unsigned int capacity;
@@ -281,7 +281,7 @@ kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size)
 }
 
 int kmem_cache_refill_sheaf(struct kmem_cache *s, gfp_t gfp,
-		 struct slab_sheaf **sheafp, unsigned int size)
+		 struct slab_sheaf **sheafp, unsigned short size)
 {
 	struct slab_sheaf *sheaf = *sheafp;
 	int refill;

-- 
2.43.0