#undef DEBUG
-#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/suspend.h>
#include <linux/module.h>
*/
#define TIMEOUT (20 * HZ)
-
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->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(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;
pr_debug("%s entered refrigerator\n", current->comm);
- frozen_process(current);
spin_lock_irq(¤t->sighand->siglock);
recalc_sigpending(); /* We sent fake signal, clean it up */
spin_unlock_irq(¤t->sighand->siglock);
- while (frozen(current)) {
- current->state = TASK_UNINTERRUPTIBLE;
+ 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);
}
-static inline void freeze_process(struct task_struct *p)
+static void fake_signal_wake_up(struct task_struct *p)
{
unsigned long flags;
+ spin_lock_irqsave(&p->sighand->siglock, flags);
+ signal_wake_up(p, 0);
+ spin_unlock_irqrestore(&p->sighand->siglock, flags);
+}
+
+static inline bool should_send_signal(struct task_struct *p)
+{
+ return !(p->flags & PF_FREEZER_NOSIG);
+}
+
+/**
+ * freeze_task - send a freeze request to given task
+ * @p: task to send the request to
+ * @sig_only: if set, the request will only be sent if the task has the
+ * PF_FREEZER_NOSIG flag unset
+ * Return value: 'false', if @sig_only is set and the task has
+ * PF_FREEZER_NOSIG set or the task is frozen, 'true', otherwise
+ *
+ * The freeze request is sent by setting 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 PF_FREEZER_NOSIG set. If @sig_only is set and the task
+ * has PF_FREEZER_NOSIG set (ie. it is a typical kernel thread), its
+ * TIF_FREEZE flag will not be set.
+ */
+static bool freeze_task(struct task_struct *p, bool sig_only)
+{
+ /*
+ * We first check if the task is freezing and next if it has already
+ * been frozen to avoid the race with frozen_process() which first marks
+ * the task as frozen and next clears its TIF_FREEZE.
+ */
if (!freezing(p)) {
- freeze(p);
- spin_lock_irqsave(&p->sighand->siglock, flags);
- signal_wake_up(p, 0);
- spin_unlock_irqrestore(&p->sighand->siglock, flags);
+ rmb();
+ if (frozen(p))
+ return false;
+
+ if (!sig_only || should_send_signal(p))
+ set_freeze_flag(p);
+ else
+ return false;
+ }
+
+ if (should_send_signal(p)) {
+ if (!signal_pending(p))
+ fake_signal_wake_up(p);
+ } else if (sig_only) {
+ return false;
+ } else {
+ wake_up_state(p, TASK_INTERRUPTIBLE);
}
+
+ return true;
}
static void cancel_freezing(struct task_struct *p)
if (freezing(p)) {
pr_debug(" clean up: %s\n", p->comm);
- do_not_freeze(p);
+ clear_freeze_flag(p);
spin_lock_irqsave(&p->sighand->siglock, flags);
- recalc_sigpending_tsk(p);
+ recalc_sigpending_and_wake(p);
spin_unlock_irqrestore(&p->sighand->siglock, flags);
}
}
-/* 0 = success, else # of processes that we failed to stop */
-int freeze_processes(void)
+static int try_to_freeze_tasks(bool sig_only)
{
- int todo, nr_user, user_frozen;
- unsigned long start_time;
struct task_struct *g, *p;
+ unsigned long end_time;
+ unsigned int todo;
+ struct timeval start, end;
+ u64 elapsed_csecs64;
+ unsigned int elapsed_csecs;
+
+ do_gettimeofday(&start);
- printk( "Stopping tasks: " );
- start_time = jiffies;
- user_frozen = 0;
+ end_time = jiffies + TIMEOUT;
do {
- nr_user = todo = 0;
+ todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
- if (!freezeable(p))
+ if (frozen(p) || !freezeable(p))
continue;
- if (frozen(p))
- continue;
- if (p->state == TASK_TRACED && frozen(p->parent)) {
- cancel_freezing(p);
+
+ if (!freeze_task(p, sig_only))
continue;
- }
- if (p->mm && !(p->flags & PF_BORROWED_MM)) {
- /* The task is a user-space one.
- * Freeze it unless there's a vfork completion
- * pending
- */
- if (!p->vfork_done)
- freeze_process(p);
- nr_user++;
- } else {
- /* Freeze only if the user space is frozen */
- if (user_frozen)
- freeze_process(p);
+
+ /*
+ * Now that we've done set_freeze_flag, don't
+ * perturb a task in TASK_STOPPED or TASK_TRACED.
+ * It is "frozen enough". If the task does wake
+ * up, it will immediately call try_to_freeze.
+ */
+ if (!task_is_stopped_or_traced(p) &&
+ !freezer_should_skip(p))
todo++;
- }
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
- todo += nr_user;
- if (!user_frozen && !nr_user) {
- sys_sync();
- start_time = jiffies;
- }
- user_frozen = !nr_user;
yield(); /* Yield is okay here */
- if (todo && time_after(jiffies, start_time + TIMEOUT))
+ if (time_after(jiffies, end_time))
break;
- } while(todo);
+ } 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;
- /* 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.
- */
if (todo) {
- printk( "\n" );
- printk(KERN_ERR " stopping tasks timed out "
- "after %d seconds (%d tasks remaining):\n",
- TIMEOUT / HZ, 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) {
- if (freezeable(p) && !frozen(p))
- printk(KERN_ERR " %s\n", p->comm);
+ 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);
- return todo;
+ } else {
+ printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
+ elapsed_csecs % 100);
}
- printk( "|\n" );
+ 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(true);
+ if (error)
+ goto Exit;
+ printk("done.\n");
+
+ printk("Freezing remaining freezable tasks ... ");
+ error = try_to_freeze_tasks(false);
+ 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(bool nosig_only)
{
struct task_struct *g, *p;
- printk( "Restarting tasks..." );
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (!freezeable(p))
continue;
- if (!thaw_process(p))
- printk(KERN_INFO " Strange, %s not stopped\n", p->comm );
- } while_each_thread(g, p);
+ if (nosig_only && should_send_signal(p))
+ continue;
+
+ thaw_process(p);
+ } while_each_thread(g, p);
read_unlock(&tasklist_lock);
+}
+
+void thaw_processes(void)
+{
+ printk("Restarting tasks ... ");
+ thaw_tasks(true);
+ thaw_tasks(false);
schedule();
- printk( " done\n" );
+ printk("done.\n");
}
EXPORT_SYMBOL(refrigerator);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff