[PATCH] change gen_pool allocator to not touch managed memory
Modify the gen_pool allocator (lib/genalloc.c) to utilize a bitmap scheme
instead of the buddy scheme. The purpose of this change is to eliminate
the touching of the actual memory being allocated.
Since the change modifies the interface, a change to the uncached allocator
(arch/ia64/kernel/uncached.c) is also required.
Both Andrey Volkov and Jes Sorenson have expressed a desire that the
gen_pool allocator not write to the memory being managed. See the
following:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113518602713125&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m=113533568827916&w=2
Signed-off-by: Dean Nelson <dcn@sgi.com>
Cc: Andrey Volkov <avolkov@varma-el.com>
Acked-by: Jes Sorensen <jes@trained-monkey.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/lib/genalloc.c b/lib/genalloc.c
index 9ce0a6a..71338b4 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -4,10 +4,6 @@
* Uses for this includes on-device special memory, uncached memory
* etc.
*
- * This code is based on the buddy allocator found in the sym53c8xx_2
- * driver Copyright (C) 1999-2001 Gerard Roudier <groudier@free.fr>,
- * and adapted for general purpose use.
- *
* Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
*
* This source code is licensed under the GNU General Public License,
@@ -15,172 +11,155 @@
*/
#include <linux/module.h>
-#include <linux/stddef.h>
-#include <linux/kernel.h>
-#include <linux/string.h>
-#include <linux/slab.h>
-#include <linux/init.h>
-#include <linux/mm.h>
-#include <linux/spinlock.h>
#include <linux/genalloc.h>
-#include <asm/page.h>
-
-struct gen_pool *gen_pool_create(int nr_chunks, int max_chunk_shift,
- unsigned long (*fp)(struct gen_pool *),
- unsigned long data)
+/*
+ * Create a new special memory pool.
+ *
+ * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
+ * @nid: node id of the node the pool structure should be allocated on, or -1
+ */
+struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
{
- struct gen_pool *poolp;
- unsigned long tmp;
- int i;
+ struct gen_pool *pool;
- /*
- * This is really an arbitrary limit, +10 is enough for
- * IA64_GRANULE_SHIFT, aka 16MB. If anyone needs a large limit
- * this can be increased without problems.
- */
- if ((max_chunk_shift > (PAGE_SHIFT + 10)) ||
- ((max_chunk_shift < ALLOC_MIN_SHIFT) && max_chunk_shift))
- return NULL;
-
- if (!max_chunk_shift)
- max_chunk_shift = PAGE_SHIFT;
-
- poolp = kmalloc(sizeof(struct gen_pool), GFP_KERNEL);
- if (!poolp)
- return NULL;
- memset(poolp, 0, sizeof(struct gen_pool));
- poolp->h = kmalloc(sizeof(struct gen_pool_link) *
- (max_chunk_shift - ALLOC_MIN_SHIFT + 1),
- GFP_KERNEL);
- if (!poolp->h) {
- printk(KERN_WARNING "gen_pool_alloc() failed to allocate\n");
- kfree(poolp);
- return NULL;
+ pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
+ if (pool != NULL) {
+ rwlock_init(&pool->lock);
+ INIT_LIST_HEAD(&pool->chunks);
+ pool->min_alloc_order = min_alloc_order;
}
- memset(poolp->h, 0, sizeof(struct gen_pool_link) *
- (max_chunk_shift - ALLOC_MIN_SHIFT + 1));
-
- spin_lock_init(&poolp->lock);
- poolp->get_new_chunk = fp;
- poolp->max_chunk_shift = max_chunk_shift;
- poolp->private = data;
-
- for (i = 0; i < nr_chunks; i++) {
- tmp = poolp->get_new_chunk(poolp);
- printk(KERN_INFO "allocated %lx\n", tmp);
- if (!tmp)
- break;
- gen_pool_free(poolp, tmp, (1 << poolp->max_chunk_shift));
- }
-
- return poolp;
+ return pool;
}
EXPORT_SYMBOL(gen_pool_create);
/*
- * Simple power of two buddy-like generic allocator.
- * Provides naturally aligned memory chunks.
+ * Add a new chunk of memory to the specified pool.
+ *
+ * @pool: pool to add new memory chunk to
+ * @addr: starting address of memory chunk to add to pool
+ * @size: size in bytes of the memory chunk to add to pool
+ * @nid: node id of the node the chunk structure and bitmap should be
+ * allocated on, or -1
*/
-unsigned long gen_pool_alloc(struct gen_pool *poolp, int size)
+int gen_pool_add(struct gen_pool *pool, unsigned long addr, size_t size,
+ int nid)
{
- int j, i, s, max_chunk_size;
- unsigned long a, flags;
- struct gen_pool_link *h = poolp->h;
+ struct gen_pool_chunk *chunk;
+ int nbits = size >> pool->min_alloc_order;
+ int nbytes = sizeof(struct gen_pool_chunk) +
+ (nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE;
- max_chunk_size = 1 << poolp->max_chunk_shift;
+ chunk = kmalloc_node(nbytes, GFP_KERNEL, nid);
+ if (unlikely(chunk == NULL))
+ return -1;
- if (size > max_chunk_size)
+ memset(chunk, 0, nbytes);
+ spin_lock_init(&chunk->lock);
+ chunk->start_addr = addr;
+ chunk->end_addr = addr + size;
+
+ write_lock(&pool->lock);
+ list_add(&chunk->next_chunk, &pool->chunks);
+ write_unlock(&pool->lock);
+
+ return 0;
+}
+EXPORT_SYMBOL(gen_pool_add);
+
+
+/*
+ * Allocate the requested number of bytes from the specified pool.
+ * Uses a first-fit algorithm.
+ *
+ * @pool: pool to allocate from
+ * @size: number of bytes to allocate from the pool
+ */
+unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
+{
+ struct list_head *_chunk;
+ struct gen_pool_chunk *chunk;
+ unsigned long addr, flags;
+ int order = pool->min_alloc_order;
+ int nbits, bit, start_bit, end_bit;
+
+ if (size == 0)
return 0;
- size = max(size, 1 << ALLOC_MIN_SHIFT);
- i = fls(size - 1);
- s = 1 << i;
- j = i -= ALLOC_MIN_SHIFT;
+ nbits = (size + (1UL << order) - 1) >> order;
- spin_lock_irqsave(&poolp->lock, flags);
- while (!h[j].next) {
- if (s == max_chunk_size) {
- struct gen_pool_link *ptr;
- spin_unlock_irqrestore(&poolp->lock, flags);
- ptr = (struct gen_pool_link *)poolp->get_new_chunk(poolp);
- spin_lock_irqsave(&poolp->lock, flags);
- h[j].next = ptr;
- if (h[j].next)
- h[j].next->next = NULL;
- break;
+ read_lock(&pool->lock);
+ list_for_each(_chunk, &pool->chunks) {
+ chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
+
+ end_bit = (chunk->end_addr - chunk->start_addr) >> order;
+ end_bit -= nbits + 1;
+
+ spin_lock_irqsave(&chunk->lock, flags);
+ bit = -1;
+ while (bit + 1 < end_bit) {
+ bit = find_next_zero_bit(chunk->bits, end_bit, bit + 1);
+ if (bit >= end_bit)
+ break;
+
+ start_bit = bit;
+ if (nbits > 1) {
+ bit = find_next_bit(chunk->bits, bit + nbits,
+ bit + 1);
+ if (bit - start_bit < nbits)
+ continue;
+ }
+
+ addr = chunk->start_addr +
+ ((unsigned long)start_bit << order);
+ while (nbits--)
+ __set_bit(start_bit++, &chunk->bits);
+ spin_unlock_irqrestore(&chunk->lock, flags);
+ read_unlock(&pool->lock);
+ return addr;
}
- j++;
- s <<= 1;
+ spin_unlock_irqrestore(&chunk->lock, flags);
}
- a = (unsigned long) h[j].next;
- if (a) {
- h[j].next = h[j].next->next;
- /*
- * This should be split into a seperate function doing
- * the chunk split in order to support custom
- * handling memory not physically accessible by host
- */
- while (j > i) {
- j -= 1;
- s >>= 1;
- h[j].next = (struct gen_pool_link *) (a + s);
- h[j].next->next = NULL;
- }
- }
- spin_unlock_irqrestore(&poolp->lock, flags);
- return a;
+ read_unlock(&pool->lock);
+ return 0;
}
EXPORT_SYMBOL(gen_pool_alloc);
/*
- * Counter-part of the generic allocator.
+ * Free the specified memory back to the specified pool.
+ *
+ * @pool: pool to free to
+ * @addr: starting address of memory to free back to pool
+ * @size: size in bytes of memory to free
*/
-void gen_pool_free(struct gen_pool *poolp, unsigned long ptr, int size)
+void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
{
- struct gen_pool_link *q;
- struct gen_pool_link *h = poolp->h;
- unsigned long a, b, flags;
- int i, s, max_chunk_size;
+ struct list_head *_chunk;
+ struct gen_pool_chunk *chunk;
+ unsigned long flags;
+ int order = pool->min_alloc_order;
+ int bit, nbits;
- max_chunk_size = 1 << poolp->max_chunk_shift;
+ nbits = (size + (1UL << order) - 1) >> order;
- if (size > max_chunk_size)
- return;
+ read_lock(&pool->lock);
+ list_for_each(_chunk, &pool->chunks) {
+ chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
- size = max(size, 1 << ALLOC_MIN_SHIFT);
- i = fls(size - 1);
- s = 1 << i;
- i -= ALLOC_MIN_SHIFT;
-
- a = ptr;
-
- spin_lock_irqsave(&poolp->lock, flags);
- while (1) {
- if (s == max_chunk_size) {
- ((struct gen_pool_link *)a)->next = h[i].next;
- h[i].next = (struct gen_pool_link *)a;
+ if (addr >= chunk->start_addr && addr < chunk->end_addr) {
+ BUG_ON(addr + size > chunk->end_addr);
+ spin_lock_irqsave(&chunk->lock, flags);
+ bit = (addr - chunk->start_addr) >> order;
+ while (nbits--)
+ __clear_bit(bit++, &chunk->bits);
+ spin_unlock_irqrestore(&chunk->lock, flags);
break;
}
- b = a ^ s;
- q = &h[i];
-
- while (q->next && q->next != (struct gen_pool_link *)b)
- q = q->next;
-
- if (!q->next) {
- ((struct gen_pool_link *)a)->next = h[i].next;
- h[i].next = (struct gen_pool_link *)a;
- break;
- }
- q->next = q->next->next;
- a = a & b;
- s <<= 1;
- i++;
}
- spin_unlock_irqrestore(&poolp->lock, flags);
+ BUG_ON(nbits > 0);
+ read_unlock(&pool->lock);
}
EXPORT_SYMBOL(gen_pool_free);