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hwmon: (tmp102) Fix jiffies wraparound in conversion-ready check

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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: 3d8f7a89a1 ("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>
This commit is contained in:
Tom Verdonck 2026-09-25 20:23:22 +02:00 committed by Guenter Roeck
parent e463cd582c
commit 56c1d32323
1 changed files with 4 additions and 4 deletions
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8
drivers/hwmon/tmp102.c
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@ -58,7 +58,7 @@ struct tmp102 {
const char *label;
struct regmap *regmap;
u16 config_orig;
unsigned long ready_time;
u64 ready_time;
u16 sample_time;
};
@ -106,7 +106,7 @@ static int tmp102_read_temp(struct device *dev, u32 attr, long *val)
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;
}
@ -354,7 +354,7 @@ 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,
@ -387,7 +387,7 @@ 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;
}