*/
#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) ||
__set_current_state(save);
}
-static void freeze_task(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)) {
rmb();
- if (!frozen(p)) {
+ if (frozen(p))
+ return false;
+
+ if (!sig_only || should_send_signal(p))
set_freeze_flag(p);
- if (p->state == TASK_STOPPED)
- force_sig_specific(SIGSTOP, p);
- spin_lock_irqsave(&p->sighand->siglock, flags);
- signal_wake_up(p, p->state == TASK_STOPPED);
- spin_unlock_irqrestore(&p->sighand->siglock, flags);
- }
+ 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)
}
}
-static int try_to_freeze_tasks(int freeze_user_space)
+static int try_to_freeze_tasks(bool sig_only)
{
struct task_struct *g, *p;
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 {
if (frozen(p) || !freezeable(p))
continue;
- if (freeze_user_space) {
- if (p->state == TASK_TRACED &&
- frozen(p->parent)) {
- cancel_freezing(p);
- continue;
- }
- /*
- * Kernel threads should not have TIF_FREEZE set
- * at this point, so we must ensure that either
- * p->mm is not NULL *and* PF_BORROWED_MM is
- * unset, or TIF_FRREZE is left unset.
- * The task_lock() is necessary to prevent races
- * with exit_mm() or use_mm()/unuse_mm() from
- * occuring.
- */
- task_lock(p);
- if (!p->mm || (p->flags & PF_BORROWED_MM)) {
- task_unlock(p);
- continue;
- }
- freeze_task(p);
- task_unlock(p);
- } else {
- freeze_task(p);
- }
- if (!freezer_should_skip(p))
+ if (!freeze_task(p, sig_only))
+ continue;
+
+ /*
+ * 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);
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,
* but it cleans up leftover PF_FREEZE requests.
*/
printk("\n");
- printk(KERN_ERR "Freezing of %s timed out after %d seconds "
+ printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
"(%d tasks refusing to freeze):\n",
- freeze_user_space ? "user space " : "tasks ",
- TIMEOUT / HZ, todo);
+ elapsed_csecs / 100, elapsed_csecs % 100, todo);
show_state();
read_lock(&tasklist_lock);
do_each_thread(g, 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;
{
int error;
- printk("Stopping tasks ... ");
- error = try_to_freeze_tasks(FREEZER_USER_SPACE);
+ printk("Freezing user space processes ... ");
+ error = try_to_freeze_tasks(true);
if (error)
- return error;
+ goto Exit;
+ printk("done.\n");
- sys_sync();
- error = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
+ printk("Freezing remaining freezable tasks ... ");
+ error = try_to_freeze_tasks(false);
if (error)
- return error;
-
- printk("done.\n");
+ goto Exit;
+ printk("done.");
+ Exit:
BUG_ON(in_atomic());
- return 0;
+ printk("\n");
+ return error;
}
-static void thaw_tasks(int thaw_user_space)
+static void thaw_tasks(bool nosig_only)
{
struct task_struct *g, *p;
if (!freezeable(p))
continue;
- if (!p->mm == thaw_user_space)
+ if (nosig_only && should_send_signal(p))
continue;
thaw_process(p);
void thaw_processes(void)
{
printk("Restarting tasks ... ");
- thaw_tasks(FREEZER_KERNEL_THREADS);
- thaw_tasks(FREEZER_USER_SPACE);
+ thaw_tasks(true);
+ thaw_tasks(false);
schedule();
printk("done.\n");
}
projects / linux-2.6-omap-h63xx.git / blobdiff