rtc: Cleanup for UIE timer/polling emulation support

hulk inclusion
category: bugfix
bugzilla: 186781, https://gitee.com/openeuler/kernel/issues/I61CEW
CVE: NA

--------------------------------

Split out a function that does not acquire ops_lock from
rtc_update_irq_enable, in preparation for fixing RTC_RD_TIME
and RTC_UIE_ON race problem.
Signed-off-by: NYu Liao <liaoyu15@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/rtc/interface.c

@@ -543,20 +543,10 @@ int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 }
 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 
-int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
+int __rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 {
-	int rc = 0, err;
+	int rc = 0, err = 0;
 
-	err = mutex_lock_interruptible(&rtc->ops_lock);
-	if (err)
-		return err;
-
-#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
-	if (enabled == 0 && rtc->uie_irq_active) {
-		mutex_unlock(&rtc->ops_lock);
-		return rtc_dev_update_irq_enable_emul(rtc, 0);
-	}
-#endif
 	/* make sure we're changing state */
 	if (rtc->uie_rtctimer.enabled == enabled)
 		goto out;
@@ -583,8 +573,6 @@ int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 	}
 
 out:
-	mutex_unlock(&rtc->ops_lock);
-
 	/*
 	 * __rtc_read_time() failed, this probably means that the RTC time has
 	 * never been set or less probably there is a transient error on the
@@ -594,6 +582,24 @@ int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 	if (rc)
 		return rc;
 
+	return err;
+}
+
+int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
+{
+	int err;
+
+#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
+	if (enabled == 0 && rtc->uie_irq_active)
+		return rtc_dev_update_irq_enable_emul(rtc, 0);
+#endif
+
+	err = mutex_lock_interruptible(&rtc->ops_lock);
+	if (err)
+		return err;
+	err = __rtc_update_irq_enable(rtc, enabled);
+	mutex_unlock(&rtc->ops_lock);
+
 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 	/*
 	 * Enable emulation if the driver returned -EINVAL to signal that it has

include/linux/rtc.h

@@ -182,6 +182,7 @@ extern void rtc_class_close(struct rtc_device *rtc);
 extern int rtc_irq_set_state(struct rtc_device *rtc, int enabled);
 extern int rtc_irq_set_freq(struct rtc_device *rtc, int freq);
 extern int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled);
+extern int __rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled);
 extern int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled);
 extern int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc,
 						unsigned int enabled);