hwmon: (tmp108) Fix jiffies wraparound in conversion-ready check

tmp108 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 initial
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. The continuous-mode path,
which sets ->ready_time to jiffies with no added conversion delay, wraps
the same way.

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: 66e1c9171339 ("hwmon: Add Texas Instruments TMP108 temperature sensor driver.")
Cc: stable@vger.kernel.org
Signed-off-by: Tom Verdonck <tom.verdonck@inspiral.be>
Link: https://patch.msgid.link/525fa49d8c50922344fa53e22be5e6133c9bbb62.1790358356.git.tom.verdonck@inspiral.be
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

0 files changed, 0 insertions, 0 deletions