/* * drivers/power/process.c - Functions for starting/stopping processes on * suspend transitions. * * Originally from swsusp. */ #undef DEBUG #include <linux/smp_lock.h> #include <linux/interrupt.h> #include <linux/suspend.h> #include <linux/module.h> #include <linux/syscalls.h> /* * Timeout for stopping processes */ #define TIMEOUT (20 * HZ) static inline int freezeable(struct task_struct * p) { if ((p == current) || (p->flags & PF_NOFREEZE) || (p->exit_state == EXIT_ZOMBIE) || (p->exit_state == EXIT_DEAD) || (p->state == TASK_STOPPED)) return 0; return 1; } /* 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; save = current->state; pr_debug("%s entered refrigerator\n", current->comm); printk("="); 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; schedule(); } pr_debug("%s left refrigerator\n", current->comm); current->state = save; } static inline void freeze_process(struct task_struct *p) { unsigned long flags; if (!freezing(p)) { freeze(p); spin_lock_irqsave(&p->sighand->siglock, flags); signal_wake_up(p, 0); spin_unlock_irqrestore(&p->sighand->siglock, flags); } } /* 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; unsigned long flags; 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->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); 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); if (freezing(p)) { pr_debug(" clean up: %s\n", p->comm); p->flags &= ~PF_FREEZE; spin_lock_irqsave(&p->sighand->siglock, flags); recalc_sigpending_tsk(p); spin_unlock_irqrestore(&p->sighand->siglock, flags); } } while_each_thread(g, p); read_unlock(&tasklist_lock); return todo; } printk( "|\n" ); BUG_ON(in_atomic()); return 0; } void thaw_processes(void) { 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); read_unlock(&tasklist_lock); schedule(); printk( " done\n" ); } EXPORT_SYMBOL(refrigerator);