Re: [PATCH 2/3] hwmon: (tmp108) Fix jiffies wraparound in conversion-ready check

[sashiko-bot@kernel.org]

> 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>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/cover.1790358356.git.tom.verdonck@inspiral.be?part=2