/* * drivers/power/process.c - Functions for starting/stopping processes on * suspend transitions. * * Originally from swsusp. */ #undef DEBUG #include <linux/interrupt.h> #include <linux/oom.h> #include <linux/suspend.h> #include <linux/module.h> #include <linux/syscalls.h> #include <linux/freezer.h> #include <linux/delay.h> #include <linux/workqueue.h> #include <linux/kmod.h> /* * Timeout for stopping processes */ #define TIMEOUT (20 * HZ) static int try_to_freeze_tasks(bool user_only) { struct task_struct *g, *p; unsigned long end_time; unsigned int todo; bool wq_busy = false; struct timeval start, end; u64 elapsed_csecs64; unsigned int elapsed_csecs; bool wakeup = false; do_gettimeofday(&start); end_time = jiffies + TIMEOUT; if (!user_only) freeze_workqueues_begin(); while (true) { todo = 0; read_lock(&tasklist_lock); do_each_thread(g, p) { if (p == current || !freeze_task(p)) 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. * * Because freeze_task() goes through p's scheduler lock, it's * guaranteed that TASK_STOPPED/TRACED -> TASK_RUNNING * transition can't race with task state testing here. */ if (!task_is_stopped_or_traced(p) && !freezer_should_skip(p)) todo++; } while_each_thread(g, p); read_unlock(&tasklist_lock); if (!user_only) { wq_busy = freeze_workqueues_busy(); todo += wq_busy; } if (!todo || time_after(jiffies, end_time)) break; if (pm_wakeup_pending()) { wakeup = true; break; } /* * We need to retry, but first give the freezing tasks some * time to enter the regrigerator. */ msleep(10); } 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) { printk("\n"); printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds " "(%d tasks refusing to freeze, wq_busy=%d):\n", wakeup ? "aborted" : "failed", elapsed_csecs / 100, elapsed_csecs % 100, todo - wq_busy, wq_busy); if (!wakeup) { read_lock(&tasklist_lock); do_each_thread(g, p) { if (p != current && !freezer_should_skip(p) && freezing(p) && !frozen(p)) sched_show_task(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; } /** * freeze_processes - Signal user space processes to enter the refrigerator. * * On success, returns 0. On failure, -errno and system is fully thawed. */ int freeze_processes(void) { int error; error = __usermodehelper_disable(UMH_FREEZING); if (error) return error; if (!pm_freezing) atomic_inc(&system_freezing_cnt); printk("Freezing user space processes ... "); pm_freezing = true; error = try_to_freeze_tasks(true); if (!error) { printk("done."); __usermodehelper_set_disable_depth(UMH_DISABLED); oom_killer_disable(); } printk("\n"); BUG_ON(in_atomic()); if (error) thaw_processes(); return error; } /** * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator. * * On success, returns 0. On failure, -errno and only the kernel threads are * thawed, so as to give a chance to the caller to do additional cleanups * (if any) before thawing the userspace tasks. So, it is the responsibility * of the caller to thaw the userspace tasks, when the time is right. */ int freeze_kernel_threads(void) { int error; printk("Freezing remaining freezable tasks ... "); pm_nosig_freezing = true; error = try_to_freeze_tasks(false); if (!error) printk("done."); printk("\n"); BUG_ON(in_atomic()); if (error) thaw_kernel_threads(); return error; } void thaw_processes(void) { struct task_struct *g, *p; if (pm_freezing) atomic_dec(&system_freezing_cnt); pm_freezing = false; pm_nosig_freezing = false; oom_killer_enable(); printk("Restarting tasks ... "); thaw_workqueues(); read_lock(&tasklist_lock); do_each_thread(g, p) { __thaw_task(p); } while_each_thread(g, p); read_unlock(&tasklist_lock); usermodehelper_enable(); schedule(); printk("done.\n"); } void thaw_kernel_threads(void) { struct task_struct *g, *p; pm_nosig_freezing = false; printk("Restarting kernel threads ... "); thaw_workqueues(); read_lock(&tasklist_lock); do_each_thread(g, p) { if (p->flags & (PF_KTHREAD | PF_WQ_WORKER)) __thaw_task(p); } while_each_thread(g, p); read_unlock(&tasklist_lock); schedule(); printk("done.\n"); }