ia64/linux-2.6.18-xen.hg

view mm/slob.c @ 871:9cbcc9008446

xen/x86: don't initialize cpu_data[]'s apicid field on generic code

Afaict, this is not only redundant with the intialization done in
drivers/xen/core/smpboot.c, but actually results - at least for
secondary CPUs - in the Xen-specific value written to be later
overwritten with whatever the generic code determines (with no
guarantee that the two values are identical).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
author Keir Fraser <keir.fraser@citrix.com>
date Thu May 14 10:09:15 2009 +0100 (2009-05-14)
parents 831230e53067
children
line source
1 /*
2 * SLOB Allocator: Simple List Of Blocks
3 *
4 * Matt Mackall <mpm@selenic.com> 12/30/03
5 *
6 * How SLOB works:
7 *
8 * The core of SLOB is a traditional K&R style heap allocator, with
9 * support for returning aligned objects. The granularity of this
10 * allocator is 8 bytes on x86, though it's perhaps possible to reduce
11 * this to 4 if it's deemed worth the effort. The slob heap is a
12 * singly-linked list of pages from __get_free_page, grown on demand
13 * and allocation from the heap is currently first-fit.
14 *
15 * Above this is an implementation of kmalloc/kfree. Blocks returned
16 * from kmalloc are 8-byte aligned and prepended with a 8-byte header.
17 * If kmalloc is asked for objects of PAGE_SIZE or larger, it calls
18 * __get_free_pages directly so that it can return page-aligned blocks
19 * and keeps a linked list of such pages and their orders. These
20 * objects are detected in kfree() by their page alignment.
21 *
22 * SLAB is emulated on top of SLOB by simply calling constructors and
23 * destructors for every SLAB allocation. Objects are returned with
24 * the 8-byte alignment unless the SLAB_MUST_HWCACHE_ALIGN flag is
25 * set, in which case the low-level allocator will fragment blocks to
26 * create the proper alignment. Again, objects of page-size or greater
27 * are allocated by calling __get_free_pages. As SLAB objects know
28 * their size, no separate size bookkeeping is necessary and there is
29 * essentially no allocation space overhead.
30 */
32 #include <linux/slab.h>
33 #include <linux/mm.h>
34 #include <linux/cache.h>
35 #include <linux/init.h>
36 #include <linux/module.h>
37 #include <linux/timer.h>
39 struct slob_block {
40 int units;
41 struct slob_block *next;
42 };
43 typedef struct slob_block slob_t;
45 #define SLOB_UNIT sizeof(slob_t)
46 #define SLOB_UNITS(size) (((size) + SLOB_UNIT - 1)/SLOB_UNIT)
47 #define SLOB_ALIGN L1_CACHE_BYTES
49 struct bigblock {
50 int order;
51 void *pages;
52 struct bigblock *next;
53 };
54 typedef struct bigblock bigblock_t;
56 static slob_t arena = { .next = &arena, .units = 1 };
57 static slob_t *slobfree = &arena;
58 static bigblock_t *bigblocks;
59 static DEFINE_SPINLOCK(slob_lock);
60 static DEFINE_SPINLOCK(block_lock);
62 static void slob_free(void *b, int size);
64 static void *slob_alloc(size_t size, gfp_t gfp, int align)
65 {
66 slob_t *prev, *cur, *aligned = 0;
67 int delta = 0, units = SLOB_UNITS(size);
68 unsigned long flags;
70 spin_lock_irqsave(&slob_lock, flags);
71 prev = slobfree;
72 for (cur = prev->next; ; prev = cur, cur = cur->next) {
73 if (align) {
74 aligned = (slob_t *)ALIGN((unsigned long)cur, align);
75 delta = aligned - cur;
76 }
77 if (cur->units >= units + delta) { /* room enough? */
78 if (delta) { /* need to fragment head to align? */
79 aligned->units = cur->units - delta;
80 aligned->next = cur->next;
81 cur->next = aligned;
82 cur->units = delta;
83 prev = cur;
84 cur = aligned;
85 }
87 if (cur->units == units) /* exact fit? */
88 prev->next = cur->next; /* unlink */
89 else { /* fragment */
90 prev->next = cur + units;
91 prev->next->units = cur->units - units;
92 prev->next->next = cur->next;
93 cur->units = units;
94 }
96 slobfree = prev;
97 spin_unlock_irqrestore(&slob_lock, flags);
98 return cur;
99 }
100 if (cur == slobfree) {
101 spin_unlock_irqrestore(&slob_lock, flags);
103 if (size == PAGE_SIZE) /* trying to shrink arena? */
104 return 0;
106 cur = (slob_t *)__get_free_page(gfp);
107 if (!cur)
108 return 0;
110 slob_free(cur, PAGE_SIZE);
111 spin_lock_irqsave(&slob_lock, flags);
112 cur = slobfree;
113 }
114 }
115 }
117 static void slob_free(void *block, int size)
118 {
119 slob_t *cur, *b = (slob_t *)block;
120 unsigned long flags;
122 if (!block)
123 return;
125 if (size)
126 b->units = SLOB_UNITS(size);
128 /* Find reinsertion point */
129 spin_lock_irqsave(&slob_lock, flags);
130 for (cur = slobfree; !(b > cur && b < cur->next); cur = cur->next)
131 if (cur >= cur->next && (b > cur || b < cur->next))
132 break;
134 if (b + b->units == cur->next) {
135 b->units += cur->next->units;
136 b->next = cur->next->next;
137 } else
138 b->next = cur->next;
140 if (cur + cur->units == b) {
141 cur->units += b->units;
142 cur->next = b->next;
143 } else
144 cur->next = b;
146 slobfree = cur;
148 spin_unlock_irqrestore(&slob_lock, flags);
149 }
151 static int FASTCALL(find_order(int size));
152 static int fastcall find_order(int size)
153 {
154 int order = 0;
155 for ( ; size > 4096 ; size >>=1)
156 order++;
157 return order;
158 }
160 void *kmalloc(size_t size, gfp_t gfp)
161 {
162 slob_t *m;
163 bigblock_t *bb;
164 unsigned long flags;
166 if (size < PAGE_SIZE - SLOB_UNIT) {
167 m = slob_alloc(size + SLOB_UNIT, gfp, 0);
168 return m ? (void *)(m + 1) : 0;
169 }
171 bb = slob_alloc(sizeof(bigblock_t), gfp, 0);
172 if (!bb)
173 return 0;
175 bb->order = find_order(size);
176 bb->pages = (void *)__get_free_pages(gfp, bb->order);
178 if (bb->pages) {
179 spin_lock_irqsave(&block_lock, flags);
180 bb->next = bigblocks;
181 bigblocks = bb;
182 spin_unlock_irqrestore(&block_lock, flags);
183 return bb->pages;
184 }
186 slob_free(bb, sizeof(bigblock_t));
187 return 0;
188 }
190 EXPORT_SYMBOL(kmalloc);
192 void kfree(const void *block)
193 {
194 bigblock_t *bb, **last = &bigblocks;
195 unsigned long flags;
197 if (!block)
198 return;
200 if (!((unsigned long)block & (PAGE_SIZE-1))) {
201 /* might be on the big block list */
202 spin_lock_irqsave(&block_lock, flags);
203 for (bb = bigblocks; bb; last = &bb->next, bb = bb->next) {
204 if (bb->pages == block) {
205 *last = bb->next;
206 spin_unlock_irqrestore(&block_lock, flags);
207 free_pages((unsigned long)block, bb->order);
208 slob_free(bb, sizeof(bigblock_t));
209 return;
210 }
211 }
212 spin_unlock_irqrestore(&block_lock, flags);
213 }
215 slob_free((slob_t *)block - 1, 0);
216 return;
217 }
219 EXPORT_SYMBOL(kfree);
221 unsigned int ksize(const void *block)
222 {
223 bigblock_t *bb;
224 unsigned long flags;
226 if (!block)
227 return 0;
229 if (!((unsigned long)block & (PAGE_SIZE-1))) {
230 spin_lock_irqsave(&block_lock, flags);
231 for (bb = bigblocks; bb; bb = bb->next)
232 if (bb->pages == block) {
233 spin_unlock_irqrestore(&slob_lock, flags);
234 return PAGE_SIZE << bb->order;
235 }
236 spin_unlock_irqrestore(&block_lock, flags);
237 }
239 return ((slob_t *)block - 1)->units * SLOB_UNIT;
240 }
242 struct kmem_cache {
243 unsigned int size, align;
244 const char *name;
245 void (*ctor)(void *, struct kmem_cache *, unsigned long);
246 void (*dtor)(void *, struct kmem_cache *, unsigned long);
247 };
249 struct kmem_cache *kmem_cache_create(const char *name, size_t size,
250 size_t align, unsigned long flags,
251 void (*ctor)(void*, struct kmem_cache *, unsigned long),
252 void (*dtor)(void*, struct kmem_cache *, unsigned long))
253 {
254 struct kmem_cache *c;
256 c = slob_alloc(sizeof(struct kmem_cache), flags, 0);
258 if (c) {
259 c->name = name;
260 c->size = size;
261 c->ctor = ctor;
262 c->dtor = dtor;
263 /* ignore alignment unless it's forced */
264 c->align = (flags & SLAB_MUST_HWCACHE_ALIGN) ? SLOB_ALIGN : 0;
265 if (c->align < align)
266 c->align = align;
267 }
269 return c;
270 }
271 EXPORT_SYMBOL(kmem_cache_create);
273 int kmem_cache_destroy(struct kmem_cache *c)
274 {
275 slob_free(c, sizeof(struct kmem_cache));
276 return 0;
277 }
278 EXPORT_SYMBOL(kmem_cache_destroy);
280 void *kmem_cache_alloc(struct kmem_cache *c, gfp_t flags)
281 {
282 void *b;
284 if (c->size < PAGE_SIZE)
285 b = slob_alloc(c->size, flags, c->align);
286 else
287 b = (void *)__get_free_pages(flags, find_order(c->size));
289 if (c->ctor)
290 c->ctor(b, c, SLAB_CTOR_CONSTRUCTOR);
292 return b;
293 }
294 EXPORT_SYMBOL(kmem_cache_alloc);
296 void *kmem_cache_zalloc(struct kmem_cache *c, gfp_t flags)
297 {
298 void *ret = kmem_cache_alloc(c, flags);
299 if (ret)
300 memset(ret, 0, c->size);
302 return ret;
303 }
304 EXPORT_SYMBOL(kmem_cache_zalloc);
306 void kmem_cache_free(struct kmem_cache *c, void *b)
307 {
308 if (c->dtor)
309 c->dtor(b, c, 0);
311 if (c->size < PAGE_SIZE)
312 slob_free(b, c->size);
313 else
314 free_pages((unsigned long)b, find_order(c->size));
315 }
316 EXPORT_SYMBOL(kmem_cache_free);
318 unsigned int kmem_cache_size(struct kmem_cache *c)
319 {
320 return c->size;
321 }
322 EXPORT_SYMBOL(kmem_cache_size);
324 const char *kmem_cache_name(struct kmem_cache *c)
325 {
326 return c->name;
327 }
328 EXPORT_SYMBOL(kmem_cache_name);
330 static struct timer_list slob_timer = TIMER_INITIALIZER(
331 (void (*)(unsigned long))kmem_cache_init, 0, 0);
333 void kmem_cache_init(void)
334 {
335 void *p = slob_alloc(PAGE_SIZE, 0, PAGE_SIZE-1);
337 if (p)
338 free_page((unsigned long)p);
340 mod_timer(&slob_timer, jiffies + HZ);
341 }
343 atomic_t slab_reclaim_pages = ATOMIC_INIT(0);
344 EXPORT_SYMBOL(slab_reclaim_pages);
346 #ifdef CONFIG_SMP
348 void *__alloc_percpu(size_t size)
349 {
350 int i;
351 struct percpu_data *pdata = kmalloc(sizeof (*pdata), GFP_KERNEL);
353 if (!pdata)
354 return NULL;
356 for_each_possible_cpu(i) {
357 pdata->ptrs[i] = kmalloc(size, GFP_KERNEL);
358 if (!pdata->ptrs[i])
359 goto unwind_oom;
360 memset(pdata->ptrs[i], 0, size);
361 }
363 /* Catch derefs w/o wrappers */
364 return (void *) (~(unsigned long) pdata);
366 unwind_oom:
367 while (--i >= 0) {
368 if (!cpu_possible(i))
369 continue;
370 kfree(pdata->ptrs[i]);
371 }
372 kfree(pdata);
373 return NULL;
374 }
375 EXPORT_SYMBOL(__alloc_percpu);
377 void
378 free_percpu(const void *objp)
379 {
380 int i;
381 struct percpu_data *p = (struct percpu_data *) (~(unsigned long) objp);
383 for_each_possible_cpu(i)
384 kfree(p->ptrs[i]);
386 kfree(p);
387 }
388 EXPORT_SYMBOL(free_percpu);
390 #endif