1/*
2 *  Collaborative memory management interface.
3 *
4 *    Copyright IBM Corp 2003, 2010
5 *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
6 *
7 */
8
9#include <linux/errno.h>
10#include <linux/fs.h>
11#include <linux/init.h>
12#include <linux/module.h>
13#include <linux/gfp.h>
14#include <linux/sched.h>
15#include <linux/sysctl.h>
16#include <linux/ctype.h>
17#include <linux/swap.h>
18#include <linux/kthread.h>
19#include <linux/oom.h>
20#include <linux/suspend.h>
21#include <linux/uaccess.h>
22
23#include <asm/pgalloc.h>
24#include <asm/diag.h>
25
26#ifdef CONFIG_CMM_IUCV
27static char *cmm_default_sender = "VMRMSVM";
28#endif
29static char *sender;
30module_param(sender, charp, 0400);
31MODULE_PARM_DESC(sender,
32		 "Guest name that may send SMSG messages (default VMRMSVM)");
33
34#include "../../../drivers/s390/net/smsgiucv.h"
35
36#define CMM_NR_PAGES ((PAGE_SIZE / sizeof(unsigned long)) - 2)
37
38struct cmm_page_array {
39	struct cmm_page_array *next;
40	unsigned long index;
41	unsigned long pages[CMM_NR_PAGES];
42};
43
44static long cmm_pages;
45static long cmm_timed_pages;
46static volatile long cmm_pages_target;
47static volatile long cmm_timed_pages_target;
48static long cmm_timeout_pages;
49static long cmm_timeout_seconds;
50static int cmm_suspended;
51
52static struct cmm_page_array *cmm_page_list;
53static struct cmm_page_array *cmm_timed_page_list;
54static DEFINE_SPINLOCK(cmm_lock);
55
56static struct task_struct *cmm_thread_ptr;
57static DECLARE_WAIT_QUEUE_HEAD(cmm_thread_wait);
58static DEFINE_TIMER(cmm_timer, NULL, 0, 0);
59
60static void cmm_timer_fn(unsigned long);
61static void cmm_set_timer(void);
62
63static long cmm_alloc_pages(long nr, long *counter,
64			    struct cmm_page_array **list)
65{
66	struct cmm_page_array *pa, *npa;
67	unsigned long addr;
68
69	while (nr) {
70		addr = __get_free_page(GFP_NOIO);
71		if (!addr)
72			break;
73		spin_lock(&cmm_lock);
74		pa = *list;
75		if (!pa || pa->index >= CMM_NR_PAGES) {
76			/* Need a new page for the page list. */
77			spin_unlock(&cmm_lock);
78			npa = (struct cmm_page_array *)
79				__get_free_page(GFP_NOIO);
80			if (!npa) {
81				free_page(addr);
82				break;
83			}
84			spin_lock(&cmm_lock);
85			pa = *list;
86			if (!pa || pa->index >= CMM_NR_PAGES) {
87				npa->next = pa;
88				npa->index = 0;
89				pa = npa;
90				*list = pa;
91			} else
92				free_page((unsigned long) npa);
93		}
94		diag10_range(addr >> PAGE_SHIFT, 1);
95		pa->pages[pa->index++] = addr;
96		(*counter)++;
97		spin_unlock(&cmm_lock);
98		nr--;
99	}
100	return nr;
101}
102
103static long cmm_free_pages(long nr, long *counter, struct cmm_page_array **list)
104{
105	struct cmm_page_array *pa;
106	unsigned long addr;
107
108	spin_lock(&cmm_lock);
109	pa = *list;
110	while (nr) {
111		if (!pa || pa->index <= 0)
112			break;
113		addr = pa->pages[--pa->index];
114		if (pa->index == 0) {
115			pa = pa->next;
116			free_page((unsigned long) *list);
117			*list = pa;
118		}
119		free_page(addr);
120		(*counter)--;
121		nr--;
122	}
123	spin_unlock(&cmm_lock);
124	return nr;
125}
126
127static int cmm_oom_notify(struct notifier_block *self,
128			  unsigned long dummy, void *parm)
129{
130	unsigned long *freed = parm;
131	long nr = 256;
132
133	nr = cmm_free_pages(nr, &cmm_timed_pages, &cmm_timed_page_list);
134	if (nr > 0)
135		nr = cmm_free_pages(nr, &cmm_pages, &cmm_page_list);
136	cmm_pages_target = cmm_pages;
137	cmm_timed_pages_target = cmm_timed_pages;
138	*freed += 256 - nr;
139	return NOTIFY_OK;
140}
141
142static struct notifier_block cmm_oom_nb = {
143	.notifier_call = cmm_oom_notify,
144};
145
146static int cmm_thread(void *dummy)
147{
148	int rc;
149
150	while (1) {
151		rc = wait_event_interruptible(cmm_thread_wait,
152			(!cmm_suspended && (cmm_pages != cmm_pages_target ||
153			 cmm_timed_pages != cmm_timed_pages_target)) ||
154			 kthread_should_stop());
155		if (kthread_should_stop() || rc == -ERESTARTSYS) {
156			cmm_pages_target = cmm_pages;
157			cmm_timed_pages_target = cmm_timed_pages;
158			break;
159		}
160		if (cmm_pages_target > cmm_pages) {
161			if (cmm_alloc_pages(1, &cmm_pages, &cmm_page_list))
162				cmm_pages_target = cmm_pages;
163		} else if (cmm_pages_target < cmm_pages) {
164			cmm_free_pages(1, &cmm_pages, &cmm_page_list);
165		}
166		if (cmm_timed_pages_target > cmm_timed_pages) {
167			if (cmm_alloc_pages(1, &cmm_timed_pages,
168					   &cmm_timed_page_list))
169				cmm_timed_pages_target = cmm_timed_pages;
170		} else if (cmm_timed_pages_target < cmm_timed_pages) {
171			cmm_free_pages(1, &cmm_timed_pages,
172				       &cmm_timed_page_list);
173		}
174		if (cmm_timed_pages > 0 && !timer_pending(&cmm_timer))
175			cmm_set_timer();
176	}
177	return 0;
178}
179
180static void cmm_kick_thread(void)
181{
182	wake_up(&cmm_thread_wait);
183}
184
185static void cmm_set_timer(void)
186{
187	if (cmm_timed_pages_target <= 0 || cmm_timeout_seconds <= 0) {
188		if (timer_pending(&cmm_timer))
189			del_timer(&cmm_timer);
190		return;
191	}
192	if (timer_pending(&cmm_timer)) {
193		if (mod_timer(&cmm_timer, jiffies + cmm_timeout_seconds*HZ))
194			return;
195	}
196	cmm_timer.function = cmm_timer_fn;
197	cmm_timer.data = 0;
198	cmm_timer.expires = jiffies + cmm_timeout_seconds*HZ;
199	add_timer(&cmm_timer);
200}
201
202static void cmm_timer_fn(unsigned long ignored)
203{
204	long nr;
205
206	nr = cmm_timed_pages_target - cmm_timeout_pages;
207	if (nr < 0)
208		cmm_timed_pages_target = 0;
209	else
210		cmm_timed_pages_target = nr;
211	cmm_kick_thread();
212	cmm_set_timer();
213}
214
215static void cmm_set_pages(long nr)
216{
217	cmm_pages_target = nr;
218	cmm_kick_thread();
219}
220
221static long cmm_get_pages(void)
222{
223	return cmm_pages;
224}
225
226static void cmm_add_timed_pages(long nr)
227{
228	cmm_timed_pages_target += nr;
229	cmm_kick_thread();
230}
231
232static long cmm_get_timed_pages(void)
233{
234	return cmm_timed_pages;
235}
236
237static void cmm_set_timeout(long nr, long seconds)
238{
239	cmm_timeout_pages = nr;
240	cmm_timeout_seconds = seconds;
241	cmm_set_timer();
242}
243
244static int cmm_skip_blanks(char *cp, char **endp)
245{
246	char *str;
247
248	for (str = cp; *str == ' ' || *str == '\t'; str++)
249		;
250	*endp = str;
251	return str != cp;
252}
253
254static struct ctl_table cmm_table[];
255
256static int cmm_pages_handler(struct ctl_table *ctl, int write,
257			     void __user *buffer, size_t *lenp, loff_t *ppos)
258{
259	char buf[16], *p;
260	unsigned int len;
261	long nr;
262
263	if (!*lenp || (*ppos && !write)) {
264		*lenp = 0;
265		return 0;
266	}
267
268	if (write) {
269		len = *lenp;
270		if (copy_from_user(buf, buffer,
271				   len > sizeof(buf) ? sizeof(buf) : len))
272			return -EFAULT;
273		buf[sizeof(buf) - 1] = '\0';
274		cmm_skip_blanks(buf, &p);
275		nr = simple_strtoul(p, &p, 0);
276		if (ctl == &cmm_table[0])
277			cmm_set_pages(nr);
278		else
279			cmm_add_timed_pages(nr);
280	} else {
281		if (ctl == &cmm_table[0])
282			nr = cmm_get_pages();
283		else
284			nr = cmm_get_timed_pages();
285		len = sprintf(buf, "%ld\n", nr);
286		if (len > *lenp)
287			len = *lenp;
288		if (copy_to_user(buffer, buf, len))
289			return -EFAULT;
290	}
291	*lenp = len;
292	*ppos += len;
293	return 0;
294}
295
296static int cmm_timeout_handler(struct ctl_table *ctl, int write,
297			       void __user *buffer, size_t *lenp, loff_t *ppos)
298{
299	char buf[64], *p;
300	long nr, seconds;
301	unsigned int len;
302
303	if (!*lenp || (*ppos && !write)) {
304		*lenp = 0;
305		return 0;
306	}
307
308	if (write) {
309		len = *lenp;
310		if (copy_from_user(buf, buffer,
311				   len > sizeof(buf) ? sizeof(buf) : len))
312			return -EFAULT;
313		buf[sizeof(buf) - 1] = '\0';
314		cmm_skip_blanks(buf, &p);
315		nr = simple_strtoul(p, &p, 0);
316		cmm_skip_blanks(p, &p);
317		seconds = simple_strtoul(p, &p, 0);
318		cmm_set_timeout(nr, seconds);
319	} else {
320		len = sprintf(buf, "%ld %ld\n",
321			      cmm_timeout_pages, cmm_timeout_seconds);
322		if (len > *lenp)
323			len = *lenp;
324		if (copy_to_user(buffer, buf, len))
325			return -EFAULT;
326	}
327	*lenp = len;
328	*ppos += len;
329	return 0;
330}
331
332static struct ctl_table cmm_table[] = {
333	{
334		.procname	= "cmm_pages",
335		.mode		= 0644,
336		.proc_handler	= cmm_pages_handler,
337	},
338	{
339		.procname	= "cmm_timed_pages",
340		.mode		= 0644,
341		.proc_handler	= cmm_pages_handler,
342	},
343	{
344		.procname	= "cmm_timeout",
345		.mode		= 0644,
346		.proc_handler	= cmm_timeout_handler,
347	},
348	{ }
349};
350
351static struct ctl_table cmm_dir_table[] = {
352	{
353		.procname	= "vm",
354		.maxlen		= 0,
355		.mode		= 0555,
356		.child		= cmm_table,
357	},
358	{ }
359};
360
361#ifdef CONFIG_CMM_IUCV
362#define SMSG_PREFIX "CMM"
363static void cmm_smsg_target(const char *from, char *msg)
364{
365	long nr, seconds;
366
367	if (strlen(sender) > 0 && strcmp(from, sender) != 0)
368		return;
369	if (!cmm_skip_blanks(msg + strlen(SMSG_PREFIX), &msg))
370		return;
371	if (strncmp(msg, "SHRINK", 6) == 0) {
372		if (!cmm_skip_blanks(msg + 6, &msg))
373			return;
374		nr = simple_strtoul(msg, &msg, 0);
375		cmm_skip_blanks(msg, &msg);
376		if (*msg == '\0')
377			cmm_set_pages(nr);
378	} else if (strncmp(msg, "RELEASE", 7) == 0) {
379		if (!cmm_skip_blanks(msg + 7, &msg))
380			return;
381		nr = simple_strtoul(msg, &msg, 0);
382		cmm_skip_blanks(msg, &msg);
383		if (*msg == '\0')
384			cmm_add_timed_pages(nr);
385	} else if (strncmp(msg, "REUSE", 5) == 0) {
386		if (!cmm_skip_blanks(msg + 5, &msg))
387			return;
388		nr = simple_strtoul(msg, &msg, 0);
389		if (!cmm_skip_blanks(msg, &msg))
390			return;
391		seconds = simple_strtoul(msg, &msg, 0);
392		cmm_skip_blanks(msg, &msg);
393		if (*msg == '\0')
394			cmm_set_timeout(nr, seconds);
395	}
396}
397#endif
398
399static struct ctl_table_header *cmm_sysctl_header;
400
401static int cmm_suspend(void)
402{
403	cmm_suspended = 1;
404	cmm_free_pages(cmm_pages, &cmm_pages, &cmm_page_list);
405	cmm_free_pages(cmm_timed_pages, &cmm_timed_pages, &cmm_timed_page_list);
406	return 0;
407}
408
409static int cmm_resume(void)
410{
411	cmm_suspended = 0;
412	cmm_kick_thread();
413	return 0;
414}
415
416static int cmm_power_event(struct notifier_block *this,
417			   unsigned long event, void *ptr)
418{
419	switch (event) {
420	case PM_POST_HIBERNATION:
421		return cmm_resume();
422	case PM_HIBERNATION_PREPARE:
423		return cmm_suspend();
424	default:
425		return NOTIFY_DONE;
426	}
427}
428
429static struct notifier_block cmm_power_notifier = {
430	.notifier_call = cmm_power_event,
431};
432
433static int __init cmm_init(void)
434{
435	int rc = -ENOMEM;
436
437	cmm_sysctl_header = register_sysctl_table(cmm_dir_table);
438	if (!cmm_sysctl_header)
439		goto out_sysctl;
440#ifdef CONFIG_CMM_IUCV
441	/* convert sender to uppercase characters */
442	if (sender) {
443		int len = strlen(sender);
444		while (len--)
445			sender[len] = toupper(sender[len]);
446	} else {
447		sender = cmm_default_sender;
448	}
449
450	rc = smsg_register_callback(SMSG_PREFIX, cmm_smsg_target);
451	if (rc < 0)
452		goto out_smsg;
453#endif
454	rc = register_oom_notifier(&cmm_oom_nb);
455	if (rc < 0)
456		goto out_oom_notify;
457	rc = register_pm_notifier(&cmm_power_notifier);
458	if (rc)
459		goto out_pm;
460	cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
461	if (!IS_ERR(cmm_thread_ptr))
462		return 0;
463
464	rc = PTR_ERR(cmm_thread_ptr);
465	unregister_pm_notifier(&cmm_power_notifier);
466out_pm:
467	unregister_oom_notifier(&cmm_oom_nb);
468out_oom_notify:
469#ifdef CONFIG_CMM_IUCV
470	smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target);
471out_smsg:
472#endif
473	unregister_sysctl_table(cmm_sysctl_header);
474out_sysctl:
475	del_timer_sync(&cmm_timer);
476	return rc;
477}
478module_init(cmm_init);
479
480static void __exit cmm_exit(void)
481{
482	unregister_sysctl_table(cmm_sysctl_header);
483#ifdef CONFIG_CMM_IUCV
484	smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target);
485#endif
486	unregister_pm_notifier(&cmm_power_notifier);
487	unregister_oom_notifier(&cmm_oom_nb);
488	kthread_stop(cmm_thread_ptr);
489	del_timer_sync(&cmm_timer);
490	cmm_free_pages(cmm_pages, &cmm_pages, &cmm_page_list);
491	cmm_free_pages(cmm_timed_pages, &cmm_timed_pages, &cmm_timed_page_list);
492}
493module_exit(cmm_exit);
494
495MODULE_LICENSE("GPL");
496