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/*
* 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.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/jffs2.h>
#include <linux/mtd/mtd.h>
#include <linux/completion.h>
#include <linux/sched/signal.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, "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, "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;
sigset_t hupmask;
siginitset(&hupmask, sigmask(SIGHUP));
allow_signal(SIGKILL);
allow_signal(SIGSTOP);
allow_signal(SIGHUP);
c->gc_task = current;
complete(&c->gc_thread_start);
set_user_nice(current, 10);
set_freezable();
for (;;) {
sigprocmask(SIG_UNBLOCK, &hupmask, NULL);
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)) {
unsigned long signr;
if (try_to_freeze())
goto again;
signr = kernel_dequeue_signal();
switch(signr) {
case SIGSTOP:
jffs2_dbg(1, "%s(): SIGSTOP received\n",
__func__);
kernel_signal_stop();
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. */
sigprocmask(SIG_BLOCK, &hupmask, NULL);
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);
kthread_complete_and_exit(&c->gc_thread_exit, 0);
}
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