diff mbox series

[v8,03/11] rtc: sun6i: Fix time overflow handling

Message ID 20210723153838.6785-4-andre.przywara@arm.com
State Superseded
Headers show
Series None | expand

Commit Message

Andre Przywara July 23, 2021, 3:38 p.m. UTC 
Using "unsigned long" for UNIX timestamps is never a good idea, and
comparing the value of such a variable against U32_MAX does not do
anything useful on 32-bit systems.

Use the proper time64_t type when dealing with timestamps, and avoid
cutting down the time range unnecessarily. This also fixes the flawed
check for the alarm time being too far into the future.

The check for this condition is actually somewhat theoretical, as the
RTC counts till 2033 only anyways, and 2^32 seconds from now is not
before the year 2157 - at which point I hope nobody will be using this
hardware anymore.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/rtc/rtc-sun6i.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

Comments

Jernej Škrabec July 25, 2021, 5:44 a.m. UTC | #1 
Hi Andre!

Dne petek, 23. julij 2021 ob 17:38:30 CEST je Andre Przywara napisal(a):
> Using "unsigned long" for UNIX timestamps is never a good idea, and
> comparing the value of such a variable against U32_MAX does not do
> anything useful on 32-bit systems.
> 
> Use the proper time64_t type when dealing with timestamps, and avoid
> cutting down the time range unnecessarily. This also fixes the flawed
> check for the alarm time being too far into the future.
> 
> The check for this condition is actually somewhat theoretical, as the
> RTC counts till 2033 only anyways, and 2^32 seconds from now is not
> before the year 2157 - at which point I hope nobody will be using this
> hardware anymore.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  drivers/rtc/rtc-sun6i.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)

Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>

Best regards,
Jernej
diff mbox series

Patch

diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
index adec1b14a8de..c551ebf0ac00 100644
--- a/drivers/rtc/rtc-sun6i.c
+++ b/drivers/rtc/rtc-sun6i.c
@@ -138,7 +138,7 @@  struct sun6i_rtc_dev {
 	const struct sun6i_rtc_clk_data *data;
 	void __iomem *base;
 	int irq;
-	unsigned long alarm;
+	time64_t alarm;
 
 	struct clk_hw hw;
 	struct clk_hw *int_osc;
@@ -510,10 +510,8 @@  static int sun6i_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
 	struct rtc_time *alrm_tm = &wkalrm->time;
 	struct rtc_time tm_now;
-	unsigned long time_now = 0;
-	unsigned long time_set = 0;
-	unsigned long time_gap = 0;
-	int ret = 0;
+	time64_t time_now, time_set;
+	int ret;
 
 	ret = sun6i_rtc_gettime(dev, &tm_now);
 	if (ret < 0) {
@@ -528,9 +526,7 @@  static int sun6i_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 		return -EINVAL;
 	}
 
-	time_gap = time_set - time_now;
-
-	if (time_gap > U32_MAX) {
+	if ((time_set - time_now) > U32_MAX) {
 		dev_err(dev, "Date too far in the future\n");
 		return -EINVAL;
 	}
@@ -539,7 +535,7 @@  static int sun6i_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 	writel(0, chip->base + SUN6I_ALRM_COUNTER);
 	usleep_range(100, 300);
 
-	writel(time_gap, chip->base + SUN6I_ALRM_COUNTER);
+	writel(time_set - time_now, chip->base + SUN6I_ALRM_COUNTER);
 	chip->alarm = time_set;
 
 	sun6i_rtc_setaie(wkalrm->enabled, chip);