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/signal.h> |
20 | #include <linux/freezer.h> |
21 | #include <linux/kthread.h> |
22 | #include "nodelist.h" |
23 | |
24 | |
25 | static int jffs2_garbage_collect_thread(void *); |
26 | |
27 | void 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 */ |
35 | int 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(x: &c->gc_thread_start); |
43 | init_completion(x: &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(ptr: 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(ptr: 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 | |
61 | void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c) |
62 | { |
63 | int wait = 0; |
64 | spin_lock(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(lock: &c->erase_completion_lock); |
71 | if (wait) |
72 | wait_for_completion(&c->gc_thread_exit); |
73 | } |
74 | |
75 | static int jffs2_garbage_collect_thread(void *_c) |
76 | { |
77 | struct jffs2_sb_info *c = _c; |
78 | sigset_t hupmask; |
79 | |
80 | siginitset(set: &hupmask, sigmask(SIGHUP)); |
81 | allow_signal(SIGKILL); |
82 | allow_signal(SIGSTOP); |
83 | allow_signal(SIGHUP); |
84 | |
85 | c->gc_task = current; |
86 | complete(&c->gc_thread_start); |
87 | |
88 | set_user_nice(current, nice: 10); |
89 | |
90 | set_freezable(); |
91 | for (;;) { |
92 | sigprocmask(SIG_UNBLOCK, &hupmask, NULL); |
93 | again: |
94 | spin_lock(lock: &c->erase_completion_lock); |
95 | if (!jffs2_thread_should_wake(c)) { |
96 | set_current_state (TASK_INTERRUPTIBLE); |
97 | spin_unlock(lock: &c->erase_completion_lock); |
98 | jffs2_dbg(1, "%s(): sleeping...\n" , __func__); |
99 | schedule(); |
100 | } else { |
101 | spin_unlock(lock: &c->erase_completion_lock); |
102 | } |
103 | /* Problem - immediately after bootup, the GCD spends a lot |
104 | * of time in places like jffs2_kill_fragtree(); so much so |
105 | * that userspace processes (like gdm and X) are starved |
106 | * despite plenty of cond_resched()s and renicing. Yield() |
107 | * doesn't help, either (presumably because userspace and GCD |
108 | * are generally competing for a higher latency resource - |
109 | * disk). |
110 | * This forces the GCD to slow the hell down. Pulling an |
111 | * inode in with read_inode() is much preferable to having |
112 | * the GC thread get there first. */ |
113 | schedule_timeout_interruptible(timeout: msecs_to_jiffies(m: 50)); |
114 | |
115 | if (kthread_should_stop()) { |
116 | jffs2_dbg(1, "%s(): kthread_stop() called\n" , __func__); |
117 | goto die; |
118 | } |
119 | |
120 | /* Put_super will send a SIGKILL and then wait on the sem. |
121 | */ |
122 | while (signal_pending(current) || freezing(current)) { |
123 | unsigned long signr; |
124 | |
125 | if (try_to_freeze()) |
126 | goto again; |
127 | |
128 | signr = kernel_dequeue_signal(); |
129 | |
130 | switch(signr) { |
131 | case SIGSTOP: |
132 | jffs2_dbg(1, "%s(): SIGSTOP received\n" , |
133 | __func__); |
134 | kernel_signal_stop(); |
135 | break; |
136 | |
137 | case SIGKILL: |
138 | jffs2_dbg(1, "%s(): SIGKILL received\n" , |
139 | __func__); |
140 | goto die; |
141 | |
142 | case SIGHUP: |
143 | jffs2_dbg(1, "%s(): SIGHUP received\n" , |
144 | __func__); |
145 | break; |
146 | default: |
147 | jffs2_dbg(1, "%s(): signal %ld received\n" , |
148 | __func__, signr); |
149 | } |
150 | } |
151 | /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */ |
152 | sigprocmask(SIG_BLOCK, &hupmask, NULL); |
153 | |
154 | jffs2_dbg(1, "%s(): pass\n" , __func__); |
155 | if (jffs2_garbage_collect_pass(c) == -ENOSPC) { |
156 | pr_notice("No space for garbage collection. Aborting GC thread\n" ); |
157 | goto die; |
158 | } |
159 | } |
160 | die: |
161 | spin_lock(lock: &c->erase_completion_lock); |
162 | c->gc_task = NULL; |
163 | spin_unlock(lock: &c->erase_completion_lock); |
164 | kthread_complete_and_exit(&c->gc_thread_exit, 0); |
165 | } |
166 | |