[PATCH 6.12.y 3/3] hwmon: (tmp102) Fix jiffies wraparound in conversion-ready check

[Sasha Levin <sashal@kernel.org>]

From: Tom Verdonck <tom.verdonck@inspiral.be>

[ Upstream commit 56c1d32323e773b8b927316f8beeae9238576335 ]

tmp102 records a one-shot deadline in ->ready_time at probe (and resume)
and, on every temperature read, refuses the read with -EAGAIN while
time_before(jiffies, ready_time) is true, in order to skip the first
~35 ms conversion.

->ready_time is an unsigned long compared with time_before(), whose
signed difference is only meaningful while the two values are within
LONG_MAX jiffies of each other. Because ->ready_time is set once and
never refreshed, jiffies keeps advancing away from it, and after 2^31
jiffies the difference flips sign. On a 32-bit HZ=100 kernel that
happens ~248.5 days after boot: time_before() then permanently reports
"not ready" and the driver returns -EAGAIN on every read, without ever
touching the sensor, until the next reboot.

Store the deadline as a 64-bit jiffies value and compare it with
get_jiffies_64()/time_before64(), which does not wrap in any practical
uptime.

Fixes: 3d8f7a89a197 ("hwmon: (tmp102) Improve handling of initial read delay")
Cc: stable@vger.kernel.org
Signed-off-by: Tom Verdonck <tom.verdonck@inspiral.be>
Link: https://patch.msgid.link/2952f070f82913aea96eec25d28008d3b9058656.1790358356.git.tom.verdonck@inspiral.be
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
[ sashal: adjusted context because the conversion-ready check is in tmp102_read() rather than tmp102_read_temp() ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/tmp102.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/tmp102.c b/drivers/hwmon/tmp102.c
index 8af44a33055f3..967d2e7e8ccf3 100644
--- a/drivers/hwmon/tmp102.c
+++ b/drivers/hwmon/tmp102.c
@@ -54,7 +54,7 @@
 struct tmp102 {
 	struct regmap *regmap;
 	u16 config_orig;
-	unsigned long ready_time;
+	u64 ready_time;
 };
 
 /* convert left adjusted 13-bit TMP102 register value to milliCelsius */
@@ -79,7 +79,7 @@ static int tmp102_read(struct device *dev, enum hwmon_sensor_types type,
 	switch (attr) {
 	case hwmon_temp_input:
 		/* Is it too early to return a conversion ? */
-		if (time_before(jiffies, tmp102->ready_time)) {
+		if (time_before64(get_jiffies_64(), tmp102->ready_time)) {
 			dev_dbg(dev, "%s: Conversion not ready yet..\n", __func__);
 			return -EAGAIN;
 		}
@@ -245,7 +245,7 @@ static int tmp102_probe(struct i2c_client *client)
 	 * Mark that we are not ready with data until the first
 	 * conversion is complete
 	 */
-	tmp102->ready_time = jiffies + msecs_to_jiffies(CONVERSION_TIME_MS);
+	tmp102->ready_time = get_jiffies_64() + msecs_to_jiffies(CONVERSION_TIME_MS);
 
 	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
 							 tmp102,
@@ -278,7 +278,7 @@ static int tmp102_resume(struct device *dev)
 	err = regmap_update_bits(tmp102->regmap, TMP102_CONF_REG,
 				 TMP102_CONF_SD, 0);
 
-	tmp102->ready_time = jiffies + msecs_to_jiffies(CONVERSION_TIME_MS);
+	tmp102->ready_time = get_jiffies_64() + msecs_to_jiffies(CONVERSION_TIME_MS);
 
 	return err;
 }
-- 
2.53.0