/* 0 = success, else # of processes that we failed to stop */
int freeze_processes(void)
{
int todo, nr_user, user_frozen;
unsigned long start_time;
struct task_struct *g, *p;
printk( "Stopping tasks: " );
start_time = jiffies;
user_frozen = 0;
do {
nr_user = todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (!freezeable(p))
continue;
if (frozen(p))
continue;
if (p->state == TASK_TRACED && frozen(p->parent)) {
cancel_freezing(p);
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 (!task_aux(p)->vfork_done)
freeze_process(p);
nr_user++;
} else {
/* Freeze only if the user space is frozen */
if (user_frozen)
freeze_process(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))
break;
} while(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.
*/
if (todo) {
printk( "\n" );
printk(KERN_ERR " stopping tasks timed out "
"after %d seconds (%d tasks remaining):\n",
TIMEOUT / HZ, todo);
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (freezeable(p) && !frozen(p))
printk(KERN_ERR " %s\n", p->comm);
cancel_freezing(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
return todo;
}
printk( "|\n" );
BUG_ON(in_atomic());
return 0;
}
static unsigned int try_to_freeze_tasks(int freeze_user_space)
{
struct task_struct *g, *p;
unsigned long end_time;
unsigned int todo;
end_time = jiffies + TIMEOUT;
do {
todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (!freezeable(p))
continue;
if (frozen(p))
continue;
if (p->state == TASK_TRACED && frozen(p->parent)) {
cancel_freezing(p);
continue;
}
if (is_user_space(p)) {
if (!freeze_user_space)
continue;
/* Freeze the task unless there is a vfork
* completion pending
*/
if (!p->vfork_done)
freeze_process(p);
} else {
if (freeze_user_space)
continue;
freeze_process(p);
}
todo++;
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
yield(); /* Yield is okay here */
if (todo && time_after(jiffies, end_time))
break;
} while (todo);
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 "Stopping %s timed out after %d seconds "
"(%d tasks refusing to freeze):\n",
freeze_user_space ? "user space processes" :
"kernel threads",
TIMEOUT / HZ, todo);
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (is_user_space(p) == !freeze_user_space)
continue;
if (freezeable(p) && !frozen(p))
printk(KERN_ERR " %s\n", p->comm);
cancel_freezing(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
}
return todo;
}
