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 1.50 2004/11/16 20:36:10 dwmw2 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 "nodelist.h" 19 20 21 static int jffs2_garbage_collect_thread(void *); 22 23 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c) 24 { 25 spin_lock(&c->erase_completion_lock); 26 if (c->gc_task && jffs2_thread_should_wake(c)) 27 send_sig(SIGHUP, c->gc_task, 1); 28 spin_unlock(&c->erase_completion_lock); 29 } 30 31 /* This must only ever be called when no GC thread is currently running */ 32 int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c) 33 { 34 pid_t pid; 35 int ret = 0; 36 37 if (c->gc_task) 38 BUG(); 39 40 init_MUTEX_LOCKED(&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 down(&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 spin_lock(&c->erase_completion_lock); 60 if (c->gc_task) { 61 D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid)); 62 send_sig(SIGKILL, c->gc_task, 1); 63 } 64 spin_unlock(&c->erase_completion_lock); 65 wait_for_completion(&c->gc_thread_exit); 66 } 67 68 static int jffs2_garbage_collect_thread(void *_c) 69 { 70 struct jffs2_sb_info *c = _c; 71 72 daemonize("jffs2_gcd_mtd%d", c->mtd->index); 73 allow_signal(SIGKILL); 74 allow_signal(SIGSTOP); 75 allow_signal(SIGCONT); 76 77 c->gc_task = current; 78 up(&c->gc_thread_start); 79 80 set_user_nice(current, 10); 81 82 for (;;) { 83 allow_signal(SIGHUP); 84 85 if (!jffs2_thread_should_wake(c)) { 86 set_current_state (TASK_INTERRUPTIBLE); 87 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n")); 88 /* Yes, there's a race here; we checked jffs2_thread_should_wake() 89 before setting current->state to TASK_INTERRUPTIBLE. But it doesn't 90 matter - We don't care if we miss a wakeup, because the GC thread 91 is only an optimisation anyway. */ 92 schedule(); 93 } 94 95 if (try_to_freeze(0)) 96 continue; 97 98 cond_resched(); 99 100 /* Put_super will send a SIGKILL and then wait on the sem. 101 */ 102 while (signal_pending(current)) { 103 siginfo_t info; 104 unsigned long signr; 105 106 signr = dequeue_signal_lock(current, ¤t->blocked, &info); 107 108 switch(signr) { 109 case SIGSTOP: 110 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n")); 111 set_current_state(TASK_STOPPED); 112 schedule(); 113 break; 114 115 case SIGKILL: 116 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n")); 117 goto die; 118 119 case SIGHUP: 120 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n")); 121 break; 122 default: 123 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr)); 124 } 125 } 126 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */ 127 disallow_signal(SIGHUP); 128 129 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n")); 130 if (jffs2_garbage_collect_pass(c) == -ENOSPC) { 131 printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n"); 132 goto die; 133 } 134 } 135 die: 136 spin_lock(&c->erase_completion_lock); 137 c->gc_task = NULL; 138 spin_unlock(&c->erase_completion_lock); 139 complete_and_exit(&c->gc_thread_exit, 0); 140 } 141