#undef DEBUG
-#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/suspend.h>
#include <linux/module.h>
+#include <linux/syscalls.h>
+#include <linux/freezer.h>
/*
* Timeout for stopping processes
*/
-#define TIMEOUT (6 * HZ)
+#define TIMEOUT (20 * HZ)
+#define FREEZER_KERNEL_THREADS 0
+#define FREEZER_USER_SPACE 1
static inline int freezeable(struct task_struct * p)
{
- if ((p == current) ||
+ if ((p == current) ||
(p->flags & PF_NOFREEZE) ||
- (p->exit_state == EXIT_ZOMBIE) ||
- (p->exit_state == EXIT_DEAD) ||
- (p->state == TASK_STOPPED) ||
- (p->state == TASK_TRACED))
+ (p->exit_state != 0))
return 0;
return 1;
}
+/*
+ * freezing is complete, mark current process as frozen
+ */
+static inline void frozen_process(void)
+{
+ if (!unlikely(current->flags & PF_NOFREEZE)) {
+ current->flags |= PF_FROZEN;
+ wmb();
+ }
+ clear_freeze_flag(current);
+}
+
/* Refrigerator is place where frozen processes are stored :-). */
-void refrigerator(unsigned long flag)
+void refrigerator(void)
{
/* Hmm, should we be allowed to suspend when there are realtime
processes around? */
long save;
+
+ task_lock(current);
+ if (freezing(current)) {
+ frozen_process();
+ task_unlock(current);
+ } else {
+ task_unlock(current);
+ return;
+ }
save = current->state;
- current->state = TASK_UNINTERRUPTIBLE;
pr_debug("%s entered refrigerator\n", current->comm);
- printk("=");
- current->flags &= ~PF_FREEZE;
spin_lock_irq(¤t->sighand->siglock);
recalc_sigpending(); /* We sent fake signal, clean it up */
spin_unlock_irq(¤t->sighand->siglock);
- current->flags |= PF_FROZEN;
- while (current->flags & PF_FROZEN)
+ for (;;) {
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ if (!frozen(current))
+ break;
schedule();
+ }
pr_debug("%s left refrigerator\n", current->comm);
- current->state = save;
+ __set_current_state(save);
}
-/* 0 = success, else # of processes that we failed to stop */
-int freeze_processes(void)
+static void fake_signal_wake_up(struct task_struct *p, int resume)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&p->sighand->siglock, flags);
+ signal_wake_up(p, resume);
+ spin_unlock_irqrestore(&p->sighand->siglock, flags);
+}
+
+static void send_fake_signal(struct task_struct *p)
+{
+ if (p->state == TASK_STOPPED)
+ force_sig_specific(SIGSTOP, p);
+ fake_signal_wake_up(p, p->state == TASK_STOPPED);
+}
+
+static int has_mm(struct task_struct *p)
+{
+ return (p->mm && !(p->flags & PF_BORROWED_MM));
+}
+
+/**
+ * freeze_task - send a freeze request to given task
+ * @p: task to send the request to
+ * @with_mm_only: if set, the request will only be sent if the task has its
+ * own mm
+ * Return value: 0, if @with_mm_only is set and the task has no mm of its
+ * own or the task is frozen, 1, otherwise
+ *
+ * The freeze request is sent by seting the tasks's TIF_FREEZE flag and
+ * either sending a fake signal to it or waking it up, depending on whether
+ * or not it has its own mm (ie. it is a user land task). If @with_mm_only
+ * is set and the task has no mm of its own (ie. it is a kernel thread),
+ * its TIF_FREEZE flag should not be set.
+ *
+ * The task_lock() is necessary to prevent races with exit_mm() or
+ * use_mm()/unuse_mm() from occuring.
+ */
+static int freeze_task(struct task_struct *p, int with_mm_only)
+{
+ int ret = 1;
+
+ task_lock(p);
+ if (freezing(p)) {
+ if (has_mm(p)) {
+ if (!signal_pending(p))
+ fake_signal_wake_up(p, 0);
+ } else {
+ if (with_mm_only)
+ ret = 0;
+ else
+ wake_up_state(p, TASK_INTERRUPTIBLE);
+ }
+ } else {
+ rmb();
+ if (frozen(p)) {
+ ret = 0;
+ } else {
+ if (has_mm(p)) {
+ set_freeze_flag(p);
+ send_fake_signal(p);
+ } else {
+ if (with_mm_only) {
+ ret = 0;
+ } else {
+ set_freeze_flag(p);
+ wake_up_state(p, TASK_INTERRUPTIBLE);
+ }
+ }
+ }
+ }
+ task_unlock(p);
+ return ret;
+}
+
+static void cancel_freezing(struct task_struct *p)
+{
+ unsigned long flags;
+
+ if (freezing(p)) {
+ pr_debug(" clean up: %s\n", p->comm);
+ clear_freeze_flag(p);
+ spin_lock_irqsave(&p->sighand->siglock, flags);
+ recalc_sigpending_and_wake(p);
+ spin_unlock_irqrestore(&p->sighand->siglock, flags);
+ }
+}
+
+static int try_to_freeze_tasks(int freeze_user_space)
{
- int todo;
- unsigned long start_time;
struct task_struct *g, *p;
-
- printk( "Stopping tasks: " );
- start_time = jiffies;
+ unsigned long end_time;
+ unsigned int todo;
+ struct timeval start, end;
+ s64 elapsed_csecs64;
+ unsigned int elapsed_csecs;
+
+ do_gettimeofday(&start);
+
+ end_time = jiffies + TIMEOUT;
do {
todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
- unsigned long flags;
- if (!freezeable(p))
+ if (frozen(p) || !freezeable(p))
+ continue;
+
+ if (p->state == TASK_TRACED && frozen(p->parent)) {
+ cancel_freezing(p);
continue;
- if ((p->flags & PF_FROZEN) ||
- (p->state == TASK_TRACED) ||
- (p->state == TASK_STOPPED))
+ }
+
+ if (!freeze_task(p, freeze_user_space))
continue;
- /* FIXME: smp problem here: we may not access other process' flags
- without locking */
- p->flags |= PF_FREEZE;
- spin_lock_irqsave(&p->sighand->siglock, flags);
- signal_wake_up(p, 0);
- spin_unlock_irqrestore(&p->sighand->siglock, flags);
- todo++;
+ if (!freezer_should_skip(p))
+ todo++;
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
yield(); /* Yield is okay here */
- if (time_after(jiffies, start_time + TIMEOUT)) {
- printk( "\n" );
- printk(KERN_ERR " stopping tasks failed (%d tasks remaining)\n", todo );
- return todo;
- }
- } while(todo);
-
- printk( "|\n" );
+ if (time_after(jiffies, end_time))
+ break;
+ } while (todo);
+
+ do_gettimeofday(&end);
+ elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
+ do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
+ elapsed_csecs = elapsed_csecs64;
+
+ if (todo) {
+ /* This does not unfreeze processes that are already frozen
+ * (we have slightly ugly calling convention in that respect,
+ * and caller must call thaw_processes() if something fails),
+ * but it cleans up leftover PF_FREEZE requests.
+ */
+ printk("\n");
+ printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
+ "(%d tasks refusing to freeze):\n",
+ elapsed_csecs / 100, elapsed_csecs % 100, todo);
+ show_state();
+ read_lock(&tasklist_lock);
+ do_each_thread(g, p) {
+ task_lock(p);
+ if (freezing(p) && !freezer_should_skip(p))
+ printk(KERN_ERR " %s\n", p->comm);
+ cancel_freezing(p);
+ task_unlock(p);
+ } while_each_thread(g, p);
+ read_unlock(&tasklist_lock);
+ } else {
+ printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
+ elapsed_csecs % 100);
+ }
+
+ return todo ? -EBUSY : 0;
+}
+
+/**
+ * freeze_processes - tell processes to enter the refrigerator
+ */
+int freeze_processes(void)
+{
+ int error;
+
+ printk("Freezing user space processes ... ");
+ error = try_to_freeze_tasks(FREEZER_USER_SPACE);
+ if (error)
+ goto Exit;
+ printk("done.\n");
+
+ printk("Freezing remaining freezable tasks ... ");
+ error = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
+ if (error)
+ goto Exit;
+ printk("done.");
+ Exit:
BUG_ON(in_atomic());
- return 0;
+ printk("\n");
+ return error;
}
-void thaw_processes(void)
+static void thaw_tasks(int thaw_user_space)
{
struct task_struct *g, *p;
- printk( "Restarting tasks..." );
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (!freezeable(p))
continue;
- if (p->flags & PF_FROZEN) {
- p->flags &= ~PF_FROZEN;
- wake_up_process(p);
- } else
- printk(KERN_INFO " Strange, %s not stopped\n", p->comm );
- } while_each_thread(g, p);
+ if (!p->mm == thaw_user_space)
+ continue;
+
+ thaw_process(p);
+ } while_each_thread(g, p);
read_unlock(&tasklist_lock);
+}
+
+void thaw_processes(void)
+{
+ printk("Restarting tasks ... ");
+ thaw_tasks(FREEZER_KERNEL_THREADS);
+ thaw_tasks(FREEZER_USER_SPACE);
schedule();
- printk( " done\n" );
+ printk("done.\n");
}
EXPORT_SYMBOL(refrigerator);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff