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1/*
2 * JFFS2 -- Journalling Flash File System, Version 2.
3 *
4 * Copyright © 2001-2007 Red Hat, Inc.
5 * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
6 *
7 * Created by David Woodhouse <dwmw2@infradead.org>
8 *
9 * For licensing information, see the file 'LICENCE' in this directory.
10 *
11 */
12
13#include <linux/kernel.h>
14#include <linux/jffs2.h>
15#include <linux/mtd/mtd.h>
16#include <linux/completion.h>
17#include <linux/sched.h>
18#include <linux/freezer.h>
19#include <linux/kthread.h>
20#include "nodelist.h"
21
22
23static int jffs2_garbage_collect_thread(void *);
24
25void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
26{
27 assert_spin_locked(&c->erase_completion_lock);
28 if (c->gc_task && jffs2_thread_should_wake(c))
29 send_sig(SIGHUP, c->gc_task, 1);
30}
31
32/* This must only ever be called when no GC thread is currently running */
33int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c)
34{
35 struct task_struct *tsk;
36 int ret = 0;
37
38 BUG_ON(c->gc_task);
39
40 init_completion(&c->gc_thread_start);
41 init_completion(&c->gc_thread_exit);
42
43 tsk = kthread_run(jffs2_garbage_collect_thread, c, "jffs2_gcd_mtd%d", c->mtd->index);
44 if (IS_ERR(tsk)) {
45 printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %ld\n", -PTR_ERR(tsk));
46 complete(&c->gc_thread_exit);
47 ret = PTR_ERR(tsk);
48 } else {
49 /* Wait for it... */
50 D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", tsk->pid));
51 wait_for_completion(&c->gc_thread_start);
52 ret = tsk->pid;
53 }
54
55 return ret;
56}
57
58void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
59{
60 int wait = 0;
61 spin_lock(&c->erase_completion_lock);
62 if (c->gc_task) {
63 D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid));
64 send_sig(SIGKILL, c->gc_task, 1);
65 wait = 1;
66 }
67 spin_unlock(&c->erase_completion_lock);
68 if (wait)
69 wait_for_completion(&c->gc_thread_exit);
70}
71
72static int jffs2_garbage_collect_thread(void *_c)
73{
74 struct jffs2_sb_info *c = _c;
75
76 allow_signal(SIGKILL);
77 allow_signal(SIGSTOP);
78 allow_signal(SIGCONT);
79
80 c->gc_task = current;
81 complete(&c->gc_thread_start);
82
83 set_user_nice(current, 10);
84
85 set_freezable();
86 for (;;) {
87 allow_signal(SIGHUP);
88 again:
89 spin_lock(&c->erase_completion_lock);
90 if (!jffs2_thread_should_wake(c)) {
91 set_current_state (TASK_INTERRUPTIBLE);
92 spin_unlock(&c->erase_completion_lock);
93 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
94 schedule();
95 } else
96 spin_unlock(&c->erase_completion_lock);
97
98
99 /* Problem - immediately after bootup, the GCD spends a lot
100 * of time in places like jffs2_kill_fragtree(); so much so
101 * that userspace processes (like gdm and X) are starved
102 * despite plenty of cond_resched()s and renicing. Yield()
103 * doesn't help, either (presumably because userspace and GCD
104 * are generally competing for a higher latency resource -
105 * disk).
106 * This forces the GCD to slow the hell down. Pulling an
107 * inode in with read_inode() is much preferable to having
108 * the GC thread get there first. */
109 schedule_timeout_interruptible(msecs_to_jiffies(50));
110
111 if (kthread_should_stop()) {
112 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): kthread_stop() called.\n"));
113 goto die;
114 }
115
116 /* Put_super will send a SIGKILL and then wait on the sem.
117 */
118 while (signal_pending(current) || freezing(current)) {
119 siginfo_t info;
120 unsigned long signr;
121
122 if (try_to_freeze())
123 goto again;
124
125 signr = dequeue_signal_lock(current, ¤t->blocked, &info);
126
127 switch(signr) {
128 case SIGSTOP:
129 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
130 set_current_state(TASK_STOPPED);
131 schedule();
132 break;
133
134 case SIGKILL:
135 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
136 goto die;
137
138 case SIGHUP:
139 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
140 break;
141 default:
142 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
143 }
144 }
145 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
146 disallow_signal(SIGHUP);
147
148 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
149 if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
150 printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
151 goto die;
152 }
153 }
154 die:
155 spin_lock(&c->erase_completion_lock);
156 c->gc_task = NULL;
157 spin_unlock(&c->erase_completion_lock);
158 complete_and_exit(&c->gc_thread_exit, 0);
159}
1/*
2 * JFFS2 -- Journalling Flash File System, Version 2.
3 *
4 * Copyright © 2001-2007 Red Hat, Inc.
5 * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
6 *
7 * Created by David Woodhouse <dwmw2@infradead.org>
8 *
9 * For licensing information, see the file 'LICENCE' in this directory.
10 *
11 */
12
13#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14
15#include <linux/kernel.h>
16#include <linux/jffs2.h>
17#include <linux/mtd/mtd.h>
18#include <linux/completion.h>
19#include <linux/sched.h>
20#include <linux/freezer.h>
21#include <linux/kthread.h>
22#include "nodelist.h"
23
24
25static int jffs2_garbage_collect_thread(void *);
26
27void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
28{
29 assert_spin_locked(&c->erase_completion_lock);
30 if (c->gc_task && jffs2_thread_should_wake(c))
31 send_sig(SIGHUP, c->gc_task, 1);
32}
33
34/* This must only ever be called when no GC thread is currently running */
35int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c)
36{
37 struct task_struct *tsk;
38 int ret = 0;
39
40 BUG_ON(c->gc_task);
41
42 init_completion(&c->gc_thread_start);
43 init_completion(&c->gc_thread_exit);
44
45 tsk = kthread_run(jffs2_garbage_collect_thread, c, "jffs2_gcd_mtd%d", c->mtd->index);
46 if (IS_ERR(tsk)) {
47 pr_warn("fork failed for JFFS2 garbage collect thread: %ld\n",
48 -PTR_ERR(tsk));
49 complete(&c->gc_thread_exit);
50 ret = PTR_ERR(tsk);
51 } else {
52 /* Wait for it... */
53 jffs2_dbg(1, "Garbage collect thread is pid %d\n", tsk->pid);
54 wait_for_completion(&c->gc_thread_start);
55 ret = tsk->pid;
56 }
57
58 return ret;
59}
60
61void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
62{
63 int wait = 0;
64 spin_lock(&c->erase_completion_lock);
65 if (c->gc_task) {
66 jffs2_dbg(1, "Killing GC task %d\n", c->gc_task->pid);
67 send_sig(SIGKILL, c->gc_task, 1);
68 wait = 1;
69 }
70 spin_unlock(&c->erase_completion_lock);
71 if (wait)
72 wait_for_completion(&c->gc_thread_exit);
73}
74
75static int jffs2_garbage_collect_thread(void *_c)
76{
77 struct jffs2_sb_info *c = _c;
78
79 allow_signal(SIGKILL);
80 allow_signal(SIGSTOP);
81 allow_signal(SIGCONT);
82
83 c->gc_task = current;
84 complete(&c->gc_thread_start);
85
86 set_user_nice(current, 10);
87
88 set_freezable();
89 for (;;) {
90 allow_signal(SIGHUP);
91 again:
92 spin_lock(&c->erase_completion_lock);
93 if (!jffs2_thread_should_wake(c)) {
94 set_current_state (TASK_INTERRUPTIBLE);
95 spin_unlock(&c->erase_completion_lock);
96 jffs2_dbg(1, "%s(): sleeping...\n", __func__);
97 schedule();
98 } else
99 spin_unlock(&c->erase_completion_lock);
100
101
102 /* Problem - immediately after bootup, the GCD spends a lot
103 * of time in places like jffs2_kill_fragtree(); so much so
104 * that userspace processes (like gdm and X) are starved
105 * despite plenty of cond_resched()s and renicing. Yield()
106 * doesn't help, either (presumably because userspace and GCD
107 * are generally competing for a higher latency resource -
108 * disk).
109 * This forces the GCD to slow the hell down. Pulling an
110 * inode in with read_inode() is much preferable to having
111 * the GC thread get there first. */
112 schedule_timeout_interruptible(msecs_to_jiffies(50));
113
114 if (kthread_should_stop()) {
115 jffs2_dbg(1, "%s(): kthread_stop() called\n", __func__);
116 goto die;
117 }
118
119 /* Put_super will send a SIGKILL and then wait on the sem.
120 */
121 while (signal_pending(current) || freezing(current)) {
122 siginfo_t info;
123 unsigned long signr;
124
125 if (try_to_freeze())
126 goto again;
127
128 signr = dequeue_signal_lock(current, ¤t->blocked, &info);
129
130 switch(signr) {
131 case SIGSTOP:
132 jffs2_dbg(1, "%s(): SIGSTOP received\n",
133 __func__);
134 set_current_state(TASK_STOPPED);
135 schedule();
136 break;
137
138 case SIGKILL:
139 jffs2_dbg(1, "%s(): SIGKILL received\n",
140 __func__);
141 goto die;
142
143 case SIGHUP:
144 jffs2_dbg(1, "%s(): SIGHUP received\n",
145 __func__);
146 break;
147 default:
148 jffs2_dbg(1, "%s(): signal %ld received\n",
149 __func__, signr);
150 }
151 }
152 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
153 disallow_signal(SIGHUP);
154
155 jffs2_dbg(1, "%s(): pass\n", __func__);
156 if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
157 pr_notice("No space for garbage collection. Aborting GC thread\n");
158 goto die;
159 }
160 }
161 die:
162 spin_lock(&c->erase_completion_lock);
163 c->gc_task = NULL;
164 spin_unlock(&c->erase_completion_lock);
165 complete_and_exit(&c->gc_thread_exit, 0);
166}