自学教程：C++ sys_sync函数代码示例

int pm_autosleep_set_state(suspend_state_t state){#ifndef CONFIG_HIBERNATION	if (state >= PM_SUSPEND_MAX)		return -EINVAL;#endif	__pm_stay_awake(autosleep_ws);	mutex_lock(&autosleep_lock);	autosleep_state = state;	__pm_relax(autosleep_ws);	if (state > PM_SUSPEND_ON) {		pm_wakep_autosleep_enabled(true);		queue_up_suspend_work();#ifndef CONFIG_PM_SYNC_BEFORE_SUSPEND		printk(KERN_INFO "PM: Syncing filesystems ... ");		sys_sync();		printk("done./n");#endif	} else {		pm_wakep_autosleep_enabled(false);	}	mutex_unlock(&autosleep_lock);	return 0;}

static void lge_dump_kernel_log(){	extern int log_buf_copy(char *dest, int idx, int len);	char log_buf[1024];	int idx = 0;	int cnt;	int h_file = 0; 	mm_segment_t oldfs = get_fs();	set_fs(KERNEL_DS);		h_file = sys_open("/data/panic.txt", O_RDWR|O_CREAT,0644);	if(h_file >= 0)	{		for (;;) {			cnt = log_buf_copy(log_buf, idx, 1023);			if (cnt <= 0)				break;			// WBT 20110314	[START]			log_buf[cnt] = 0;			// WBT 20110314	[END]			sys_write(h_file,log_buf,cnt);			idx += cnt;		}				sys_close(h_file);	}	else	{		printk("Can't open log file ret = %d./n",h_file);				}		sys_sync();	set_fs(oldfs);}

/** *	hom_prepare - Do prep work before entering low-power state. * *	This is common code that is called for each state that we're entering. *	Run suspend notifiers, allocate a console and stop all processes. */static int hom_prepare(void){	int error;	pm_prepare_console();	error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);	if (error)		goto Exit;	error = usermodehelper_disable();	if (error)		goto Exit;	pr_info("PM: Syncing filesystems ... ");	sys_sync();	pr_info("done./n");	error = prepare_processes();	if (!error)		return 0;	usermodehelper_enable();Exit:	pm_notifier_call_chain(PM_POST_HIBERNATION);	pm_restore_console();	return error;}

int hibernate(void){	int error;	mutex_lock(&pm_mutex);	/* The snapshot device should not be opened while we're running */	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {		error = -EBUSY;		goto Unlock;	}	error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);	if (error)		goto Exit;	/* Allocate memory management structures */	error = create_basic_memory_bitmaps();	if (error)		goto Exit;	printk("Syncing filesystems ... ");	sys_sync();	printk("done./n");	error = prepare_processes();	if (error)		goto Finish;	if (hibernation_mode == HIBERNATION_TESTPROC) {		printk("swsusp debug: Waiting for 5 seconds./n");		mdelay(5000);		goto Thaw;	}	error = hibernation_snapshot(hibernation_mode == HIBERNATION_PLATFORM);	if (in_suspend && !error) {		unsigned int flags = 0;		if (hibernation_mode == HIBERNATION_PLATFORM)			flags |= SF_PLATFORM_MODE;		pr_debug("PM: writing image./n");		error = swsusp_write(flags);		swsusp_free();		if (!error)			power_down();	} else {		pr_debug("PM: Image restored successfully./n");		swsusp_free();	} Thaw:	unprepare_processes(); Finish:	free_basic_memory_bitmaps(); Exit:	pm_notifier_call_chain(PM_POST_HIBERNATION);	atomic_inc(&snapshot_device_available); Unlock:	mutex_unlock(&pm_mutex);	return error;}

static void poweroff(struct work_struct *work){	synchronous_emergency_remount();	sys_sync();	printk(KERN_EMERG "Filesystems synced./n");	kernel_power_off();}

static void do_restart(void){#if defined(CONFIG_POWER_KEY_CLR_RESET)	clear_hw_reset();#endif	sys_sync();	machine_restart("power-key-force-hard");}

NORET_TYPE void panic(const char * fmt, ...){	static char buf[1024];	va_list args;#if defined(CONFIG_ARCH_S390)        unsigned long caller = (unsigned long) __builtin_return_address(0);#endif	bust_spinlocks(1);	va_start(args, fmt);	vsprintf(buf, fmt, args);	va_end(args);	printk(KERN_EMERG "Kernel panic: %s/n",buf);	if (in_interrupt())		printk(KERN_EMERG "In interrupt handler - not syncing/n");	else if (!current->pid)		printk(KERN_EMERG "In idle task - not syncing/n");	else		sys_sync();	bust_spinlocks(0);#ifdef CONFIG_SMP	smp_send_stop();#endif	notifier_call_chain(&panic_notifier_list, 0, NULL);	if (panic_timeout > 0)	{		/*	 	 * Delay timeout seconds before rebooting the machine. 		 * We can't use the "normal" timers since we just panicked..	 	 */		printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);		mdelay(panic_timeout*1000);		/*		 *	Should we run the reboot notifier. For the moment Im		 *	choosing not too. It might crash, be corrupt or do		 *	more harm than good for other reasons.		 */		machine_restart(NULL);	}#ifdef __sparc__	{		extern int stop_a_enabled;		/* Make sure the user can actually press L1-A */		stop_a_enabled = 1;		printk("Press L1-A to return to the boot prom/n");	}#endif#if defined(CONFIG_ARCH_S390)        disabled_wait(caller);#endif	sti();	for(;;) {		CHECK_EMERGENCY_SYNC	}}

// 该函数用来显示内核中出现重大错误信息，并运行文件系统同步函数，然后进入// 死循环
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