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