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   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, &current->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 }