1 /* 2 * JFFS2 -- Journalling Flash File System, Version 2. 3 * 4 * Copyright (C) 2001-2003 Red Hat, Inc. 5 * 6 * Created by David Woodhouse <dwmw2@infradead.org> 7 * 8 * For licensing information, see the file 'LICENCE' in this directory. 9 * 10 * $Id: background.c,v 1.54 2005/05/20 21:37:12 gleixner Exp $ 11 * 12 */ 13 14 #include <linux/kernel.h> 15 #include <linux/jffs2.h> 16 #include <linux/mtd/mtd.h> 17 #include <linux/completion.h> 18 #include <linux/sched.h> 19 #include "nodelist.h" 20 21 22 static int jffs2_garbage_collect_thread(void *); 23 24 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c) 25 { 26 spin_lock(&c->erase_completion_lock); 27 if (c->gc_task && jffs2_thread_should_wake(c)) 28 send_sig(SIGHUP, c->gc_task, 1); 29 spin_unlock(&c->erase_completion_lock); 30 } 31 32 /* This must only ever be called when no GC thread is currently running */ 33 int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c) 34 { 35 pid_t pid; 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 pid = kernel_thread(jffs2_garbage_collect_thread, c, CLONE_FS|CLONE_FILES); 44 if (pid < 0) { 45 printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %d\n", -pid); 46 complete(&c->gc_thread_exit); 47 ret = pid; 48 } else { 49 /* Wait for it... */ 50 D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", pid)); 51 wait_for_completion(&c->gc_thread_start); 52 } 53 54 return ret; 55 } 56 57 void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c) 58 { 59 int wait = 0; 60 spin_lock(&c->erase_completion_lock); 61 if (c->gc_task) { 62 D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid)); 63 send_sig(SIGKILL, c->gc_task, 1); 64 wait = 1; 65 } 66 spin_unlock(&c->erase_completion_lock); 67 if (wait) 68 wait_for_completion(&c->gc_thread_exit); 69 } 70 71 static int jffs2_garbage_collect_thread(void *_c) 72 { 73 struct jffs2_sb_info *c = _c; 74 75 daemonize("jffs2_gcd_mtd%d", c->mtd->index); 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 for (;;) { 86 allow_signal(SIGHUP); 87 88 if (!jffs2_thread_should_wake(c)) { 89 set_current_state (TASK_INTERRUPTIBLE); 90 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n")); 91 /* Yes, there's a race here; we checked jffs2_thread_should_wake() 92 before setting current->state to TASK_INTERRUPTIBLE. But it doesn't 93 matter - We don't care if we miss a wakeup, because the GC thread 94 is only an optimisation anyway. */ 95 schedule(); 96 } 97 98 if (try_to_freeze()) 99 continue; 100 101 cond_resched(); 102 103 /* Put_super will send a SIGKILL and then wait on the sem. 104 */ 105 while (signal_pending(current)) { 106 siginfo_t info; 107 unsigned long signr; 108 109 signr = dequeue_signal_lock(current, ¤t->blocked, &info); 110 111 switch(signr) { 112 case SIGSTOP: 113 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n")); 114 set_current_state(TASK_STOPPED); 115 schedule(); 116 break; 117 118 case SIGKILL: 119 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n")); 120 goto die; 121 122 case SIGHUP: 123 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n")); 124 break; 125 default: 126 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr)); 127 } 128 } 129 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */ 130 disallow_signal(SIGHUP); 131 132 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n")); 133 if (jffs2_garbage_collect_pass(c) == -ENOSPC) { 134 printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n"); 135 goto die; 136 } 137 } 138 die: 139 spin_lock(&c->erase_completion_lock); 140 c->gc_task = NULL; 141 spin_unlock(&c->erase_completion_lock); 142 complete_and_exit(&c->gc_thread_exit, 0); 143 } 144