| /* |
| * 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. |
| * |
| */ |
| |
| #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, "JFFS2: 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, "jffs2: 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; |
| |
| allow_signal(SIGKILL); |
| allow_signal(SIGSTOP); |
| allow_signal(SIGCONT); |
| |
| c->gc_task = current; |
| complete(&c->gc_thread_start); |
| |
| set_user_nice(current, 10); |
| |
| set_freezable(); |
| for (;;) { |
| allow_signal(SIGHUP); |
| 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)) { |
| siginfo_t info; |
| unsigned long signr; |
| |
| if (try_to_freeze()) |
| goto again; |
| |
| signr = dequeue_signal_lock(current, ¤t->blocked, &info); |
| |
| switch(signr) { |
| case SIGSTOP: |
| jffs2_dbg(1, "%s(): SIGSTOP received\n", |
| __func__); |
| set_current_state(TASK_STOPPED); |
| schedule(); |
| 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. */ |
| disallow_signal(SIGHUP); |
| |
| 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); |
| } |