From: Yu Liao <liaoyu15@huawei.com>
To: <alexandre.belloni@bootlin.com>, <a.zummo@towertech.it>
Cc: <liaoyu15@huawei.com>, <liwei391@huawei.com>,
<linux-kernel@vger.kernel.org>, <linux-rtc@vger.kernel.org>
Subject: [RFC PATCH 1/2] rtc: add lockless rtc_update_irq_enable
Date: Wed, 26 Oct 2022 11:33:47 +0800 [thread overview]
Message-ID: <20221026033348.1660732-2-liaoyu15@huawei.com> (raw)
In-Reply-To: <20221026033348.1660732-1-liaoyu15@huawei.com>
Split out a function that does not acquire rtc->ops_lock from
rtc_update_irq_enable, in preparation for fixing race condition in
rtc_set_time.
Signed-off-by: Yu Liao <liaoyu15@huawei.com>
---
drivers/rtc/interface.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 9edd662c69ac..bc55dd31bece 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -19,6 +19,7 @@
static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
+static int __rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled);
static void rtc_add_offset(struct rtc_device *rtc, struct rtc_time *tm)
{
@@ -81,6 +82,7 @@ static int rtc_valid_range(struct rtc_device *rtc, struct rtc_time *tm)
return 0;
}
+/* This function must be called with rtc->ops_lock held */
static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
{
int err;
@@ -553,27 +555,21 @@ 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)
+static int __rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
{
- int err;
-
- err = mutex_lock_interruptible(&rtc->ops_lock);
- if (err)
- return err;
+ int err = 0;
#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;
+ return err;
if (!test_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features) ||
!test_bit(RTC_FEATURE_ALARM, rtc->features)) {
- mutex_unlock(&rtc->ops_lock);
#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
return rtc_dev_update_irq_enable_emul(rtc, enabled);
#else
@@ -587,7 +583,7 @@ int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
err = __rtc_read_time(rtc, &tm);
if (err)
- goto out;
+ return err;
onesec = ktime_set(1, 0);
now = rtc_tm_to_ktime(tm);
rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
@@ -597,7 +593,19 @@ int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
rtc_timer_remove(rtc, &rtc->uie_rtctimer);
}
-out:
+ return err;
+}
+
+int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
+{
+ int err;
+
+ err = mutex_lock_interruptible(&rtc->ops_lock);
+ if (err)
+ return err;
+
+ err = __rtc_update_irq_enable(rtc, enabled);
+
mutex_unlock(&rtc->ops_lock);
return err;
--
2.25.1
next prev parent reply other threads:[~2022-10-26 3:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-26 3:33 [RFC PATCH 0/2] rtc: fix race condition between uie enable and rtc set time Yu Liao
2022-10-26 3:33 ` Yu Liao [this message]
2022-10-26 3:33 ` [RFC PATCH 2/2] rtc: fix race condition in rtc_set_time() Yu Liao
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