Merge git://git.infradead.org/mtd-2.6
[linux-2.6] / arch / s390 / mm / cmm.c
1 /*
2  *  arch/s390/mm/cmm.c
3  *
4  *  S390 version
5  *    Copyright (C) 2003 IBM Deutschland Entwicklung GmbH, IBM Corporation
6  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
7  *
8  *  Collaborative memory management interface.
9  */
10
11 #include <linux/errno.h>
12 #include <linux/fs.h>
13 #include <linux/init.h>
14 #include <linux/module.h>
15 #include <linux/sched.h>
16 #include <linux/sysctl.h>
17 #include <linux/ctype.h>
18 #include <linux/swap.h>
19 #include <linux/kthread.h>
20
21 #include <asm/pgalloc.h>
22 #include <asm/uaccess.h>
23
24 static char *sender = "VMRMSVM";
25 module_param(sender, charp, 0400);
26 MODULE_PARM_DESC(sender,
27                  "Guest name that may send SMSG messages (default VMRMSVM)");
28
29 #include "../../../drivers/s390/net/smsgiucv.h"
30
31 #define CMM_NR_PAGES ((PAGE_SIZE / sizeof(unsigned long)) - 2)
32
33 struct cmm_page_array {
34         struct cmm_page_array *next;
35         unsigned long index;
36         unsigned long pages[CMM_NR_PAGES];
37 };
38
39 static long cmm_pages;
40 static long cmm_timed_pages;
41 static volatile long cmm_pages_target;
42 static volatile long cmm_timed_pages_target;
43 static long cmm_timeout_pages;
44 static long cmm_timeout_seconds;
45
46 static struct cmm_page_array *cmm_page_list;
47 static struct cmm_page_array *cmm_timed_page_list;
48 static DEFINE_SPINLOCK(cmm_lock);
49
50 static struct task_struct *cmm_thread_ptr;
51 static wait_queue_head_t cmm_thread_wait;
52 static struct timer_list cmm_timer;
53
54 static void cmm_timer_fn(unsigned long);
55 static void cmm_set_timer(void);
56
57 static long
58 cmm_alloc_pages(long nr, long *counter, struct cmm_page_array **list)
59 {
60         struct cmm_page_array *pa, *npa;
61         unsigned long addr;
62
63         while (nr) {
64                 addr = __get_free_page(GFP_NOIO);
65                 if (!addr)
66                         break;
67                 spin_lock(&cmm_lock);
68                 pa = *list;
69                 if (!pa || pa->index >= CMM_NR_PAGES) {
70                         /* Need a new page for the page list. */
71                         spin_unlock(&cmm_lock);
72                         npa = (struct cmm_page_array *)
73                                 __get_free_page(GFP_NOIO);
74                         if (!npa) {
75                                 free_page(addr);
76                                 break;
77                         }
78                         spin_lock(&cmm_lock);
79                         pa = *list;
80                         if (!pa || pa->index >= CMM_NR_PAGES) {
81                                 npa->next = pa;
82                                 npa->index = 0;
83                                 pa = npa;
84                                 *list = pa;
85                         } else
86                                 free_page((unsigned long) npa);
87                 }
88                 diag10(addr);
89                 pa->pages[pa->index++] = addr;
90                 (*counter)++;
91                 spin_unlock(&cmm_lock);
92                 nr--;
93         }
94         return nr;
95 }
96
97 static long
98 cmm_free_pages(long nr, long *counter, struct cmm_page_array **list)
99 {
100         struct cmm_page_array *pa;
101         unsigned long addr;
102
103         spin_lock(&cmm_lock);
104         pa = *list;
105         while (nr) {
106                 if (!pa || pa->index <= 0)
107                         break;
108                 addr = pa->pages[--pa->index];
109                 if (pa->index == 0) {
110                         pa = pa->next;
111                         free_page((unsigned long) *list);
112                         *list = pa;
113                 }
114                 free_page(addr);
115                 (*counter)--;
116                 nr--;
117         }
118         spin_unlock(&cmm_lock);
119         return nr;
120 }
121
122 static int cmm_oom_notify(struct notifier_block *self,
123                           unsigned long dummy, void *parm)
124 {
125         unsigned long *freed = parm;
126         long nr = 256;
127
128         nr = cmm_free_pages(nr, &cmm_timed_pages, &cmm_timed_page_list);
129         if (nr > 0)
130                 nr = cmm_free_pages(nr, &cmm_pages, &cmm_page_list);
131         cmm_pages_target = cmm_pages;
132         cmm_timed_pages_target = cmm_timed_pages;
133         *freed += 256 - nr;
134         return NOTIFY_OK;
135 }
136
137 static struct notifier_block cmm_oom_nb = {
138         .notifier_call = cmm_oom_notify
139 };
140
141 static int
142 cmm_thread(void *dummy)
143 {
144         int rc;
145
146         while (1) {
147                 rc = wait_event_interruptible(cmm_thread_wait,
148                         (cmm_pages != cmm_pages_target ||
149                          cmm_timed_pages != cmm_timed_pages_target ||
150                          kthread_should_stop()));
151                 if (kthread_should_stop() || rc == -ERESTARTSYS) {
152                         cmm_pages_target = cmm_pages;
153                         cmm_timed_pages_target = cmm_timed_pages;
154                         break;
155                 }
156                 if (cmm_pages_target > cmm_pages) {
157                         if (cmm_alloc_pages(1, &cmm_pages, &cmm_page_list))
158                                 cmm_pages_target = cmm_pages;
159                 } else if (cmm_pages_target < cmm_pages) {
160                         cmm_free_pages(1, &cmm_pages, &cmm_page_list);
161                 }
162                 if (cmm_timed_pages_target > cmm_timed_pages) {
163                         if (cmm_alloc_pages(1, &cmm_timed_pages,
164                                            &cmm_timed_page_list))
165                                 cmm_timed_pages_target = cmm_timed_pages;
166                 } else if (cmm_timed_pages_target < cmm_timed_pages) {
167                         cmm_free_pages(1, &cmm_timed_pages,
168                                        &cmm_timed_page_list);
169                 }
170                 if (cmm_timed_pages > 0 && !timer_pending(&cmm_timer))
171                         cmm_set_timer();
172         }
173         return 0;
174 }
175
176 static void
177 cmm_kick_thread(void)
178 {
179         wake_up(&cmm_thread_wait);
180 }
181
182 static void
183 cmm_set_timer(void)
184 {
185         if (cmm_timed_pages_target <= 0 || cmm_timeout_seconds <= 0) {
186                 if (timer_pending(&cmm_timer))
187                         del_timer(&cmm_timer);
188                 return;
189         }
190         if (timer_pending(&cmm_timer)) {
191                 if (mod_timer(&cmm_timer, jiffies + cmm_timeout_seconds*HZ))
192                         return;
193         }
194         cmm_timer.function = cmm_timer_fn;
195         cmm_timer.data = 0;
196         cmm_timer.expires = jiffies + cmm_timeout_seconds*HZ;
197         add_timer(&cmm_timer);
198 }
199
200 static void
201 cmm_timer_fn(unsigned long ignored)
202 {
203         long nr;
204
205         nr = cmm_timed_pages_target - cmm_timeout_pages;
206         if (nr < 0)
207                 cmm_timed_pages_target = 0;
208         else
209                 cmm_timed_pages_target = nr;
210         cmm_kick_thread();
211         cmm_set_timer();
212 }
213
214 void
215 cmm_set_pages(long nr)
216 {
217         cmm_pages_target = nr;
218         cmm_kick_thread();
219 }
220
221 long
222 cmm_get_pages(void)
223 {
224         return cmm_pages;
225 }
226
227 void
228 cmm_add_timed_pages(long nr)
229 {
230         cmm_timed_pages_target += nr;
231         cmm_kick_thread();
232 }
233
234 long
235 cmm_get_timed_pages(void)
236 {
237         return cmm_timed_pages;
238 }
239
240 void
241 cmm_set_timeout(long nr, long seconds)
242 {
243         cmm_timeout_pages = nr;
244         cmm_timeout_seconds = seconds;
245         cmm_set_timer();
246 }
247
248 static int
249 cmm_skip_blanks(char *cp, char **endp)
250 {
251         char *str;
252
253         for (str = cp; *str == ' ' || *str == '\t'; str++);
254         *endp = str;
255         return str != cp;
256 }
257
258 #ifdef CONFIG_CMM_PROC
259
260 static struct ctl_table cmm_table[];
261
262 static int
263 cmm_pages_handler(ctl_table *ctl, int write, struct file *filp,
264                   void __user *buffer, size_t *lenp, loff_t *ppos)
265 {
266         char buf[16], *p;
267         long nr;
268         int len;
269
270         if (!*lenp || (*ppos && !write)) {
271                 *lenp = 0;
272                 return 0;
273         }
274
275         if (write) {
276                 len = *lenp;
277                 if (copy_from_user(buf, buffer,
278                                    len > sizeof(buf) ? sizeof(buf) : len))
279                         return -EFAULT;
280                 buf[sizeof(buf) - 1] = '\0';
281                 cmm_skip_blanks(buf, &p);
282                 nr = simple_strtoul(p, &p, 0);
283                 if (ctl == &cmm_table[0])
284                         cmm_set_pages(nr);
285                 else
286                         cmm_add_timed_pages(nr);
287         } else {
288                 if (ctl == &cmm_table[0])
289                         nr = cmm_get_pages();
290                 else
291                         nr = cmm_get_timed_pages();
292                 len = sprintf(buf, "%ld\n", nr);
293                 if (len > *lenp)
294                         len = *lenp;
295                 if (copy_to_user(buffer, buf, len))
296                         return -EFAULT;
297         }
298         *lenp = len;
299         *ppos += len;
300         return 0;
301 }
302
303 static int
304 cmm_timeout_handler(ctl_table *ctl, int write, struct file *filp,
305                     void __user *buffer, size_t *lenp, loff_t *ppos)
306 {
307         char buf[64], *p;
308         long nr, seconds;
309         int len;
310
311         if (!*lenp || (*ppos && !write)) {
312                 *lenp = 0;
313                 return 0;
314         }
315
316         if (write) {
317                 len = *lenp;
318                 if (copy_from_user(buf, buffer,
319                                    len > sizeof(buf) ? sizeof(buf) : len))
320                         return -EFAULT;
321                 buf[sizeof(buf) - 1] = '\0';
322                 cmm_skip_blanks(buf, &p);
323                 nr = simple_strtoul(p, &p, 0);
324                 cmm_skip_blanks(p, &p);
325                 seconds = simple_strtoul(p, &p, 0);
326                 cmm_set_timeout(nr, seconds);
327         } else {
328                 len = sprintf(buf, "%ld %ld\n",
329                               cmm_timeout_pages, cmm_timeout_seconds);
330                 if (len > *lenp)
331                         len = *lenp;
332                 if (copy_to_user(buffer, buf, len))
333                         return -EFAULT;
334         }
335         *lenp = len;
336         *ppos += len;
337         return 0;
338 }
339
340 static struct ctl_table cmm_table[] = {
341         {
342                 .ctl_name       = VM_CMM_PAGES,
343                 .procname       = "cmm_pages",
344                 .mode           = 0644,
345                 .proc_handler   = &cmm_pages_handler,
346         },
347         {
348                 .ctl_name       = VM_CMM_TIMED_PAGES,
349                 .procname       = "cmm_timed_pages",
350                 .mode           = 0644,
351                 .proc_handler   = &cmm_pages_handler,
352         },
353         {
354                 .ctl_name       = VM_CMM_TIMEOUT,
355                 .procname       = "cmm_timeout",
356                 .mode           = 0644,
357                 .proc_handler   = &cmm_timeout_handler,
358         },
359         { .ctl_name = 0 }
360 };
361
362 static struct ctl_table cmm_dir_table[] = {
363         {
364                 .ctl_name       = CTL_VM,
365                 .procname       = "vm",
366                 .maxlen         = 0,
367                 .mode           = 0555,
368                 .child          = cmm_table,
369         },
370         { .ctl_name = 0 }
371 };
372 #endif
373
374 #ifdef CONFIG_CMM_IUCV
375 #define SMSG_PREFIX "CMM"
376 static void
377 cmm_smsg_target(char *from, char *msg)
378 {
379         long nr, seconds;
380
381         if (strlen(sender) > 0 && strcmp(from, sender) != 0)
382                 return;
383         if (!cmm_skip_blanks(msg + strlen(SMSG_PREFIX), &msg))
384                 return;
385         if (strncmp(msg, "SHRINK", 6) == 0) {
386                 if (!cmm_skip_blanks(msg + 6, &msg))
387                         return;
388                 nr = simple_strtoul(msg, &msg, 0);
389                 cmm_skip_blanks(msg, &msg);
390                 if (*msg == '\0')
391                         cmm_set_pages(nr);
392         } else if (strncmp(msg, "RELEASE", 7) == 0) {
393                 if (!cmm_skip_blanks(msg + 7, &msg))
394                         return;
395                 nr = simple_strtoul(msg, &msg, 0);
396                 cmm_skip_blanks(msg, &msg);
397                 if (*msg == '\0')
398                         cmm_add_timed_pages(nr);
399         } else if (strncmp(msg, "REUSE", 5) == 0) {
400                 if (!cmm_skip_blanks(msg + 5, &msg))
401                         return;
402                 nr = simple_strtoul(msg, &msg, 0);
403                 if (!cmm_skip_blanks(msg, &msg))
404                         return;
405                 seconds = simple_strtoul(msg, &msg, 0);
406                 cmm_skip_blanks(msg, &msg);
407                 if (*msg == '\0')
408                         cmm_set_timeout(nr, seconds);
409         }
410 }
411 #endif
412
413 static struct ctl_table_header *cmm_sysctl_header;
414
415 static int
416 cmm_init (void)
417 {
418         int rc = -ENOMEM;
419
420 #ifdef CONFIG_CMM_PROC
421         cmm_sysctl_header = register_sysctl_table(cmm_dir_table);
422         if (!cmm_sysctl_header)
423                 goto out;
424 #endif
425 #ifdef CONFIG_CMM_IUCV
426         rc = smsg_register_callback(SMSG_PREFIX, cmm_smsg_target);
427         if (rc < 0)
428                 goto out_smsg;
429 #endif
430         rc = register_oom_notifier(&cmm_oom_nb);
431         if (rc < 0)
432                 goto out_oom_notify;
433         init_waitqueue_head(&cmm_thread_wait);
434         init_timer(&cmm_timer);
435         cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
436         rc = IS_ERR(cmm_thread_ptr) ? PTR_ERR(cmm_thread_ptr) : 0;
437         if (!rc)
438                 goto out;
439         /*
440          * kthread_create failed. undo all the stuff from above again.
441          */
442         unregister_oom_notifier(&cmm_oom_nb);
443
444 out_oom_notify:
445 #ifdef CONFIG_CMM_IUCV
446         smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target);
447 out_smsg:
448 #endif
449 #ifdef CONFIG_CMM_PROC
450         unregister_sysctl_table(cmm_sysctl_header);
451 #endif
452 out:
453         return rc;
454 }
455
456 static void
457 cmm_exit(void)
458 {
459         kthread_stop(cmm_thread_ptr);
460         unregister_oom_notifier(&cmm_oom_nb);
461         cmm_free_pages(cmm_pages, &cmm_pages, &cmm_page_list);
462         cmm_free_pages(cmm_timed_pages, &cmm_timed_pages, &cmm_timed_page_list);
463 #ifdef CONFIG_CMM_PROC
464         unregister_sysctl_table(cmm_sysctl_header);
465 #endif
466 #ifdef CONFIG_CMM_IUCV
467         smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target);
468 #endif
469 }
470
471 module_init(cmm_init);
472 module_exit(cmm_exit);
473
474 EXPORT_SYMBOL(cmm_set_pages);
475 EXPORT_SYMBOL(cmm_get_pages);
476 EXPORT_SYMBOL(cmm_add_timed_pages);
477 EXPORT_SYMBOL(cmm_get_timed_pages);
478 EXPORT_SYMBOL(cmm_set_timeout);
479
480 MODULE_LICENSE("GPL");