/* 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; }