Re: [PATCH v2] serial: max3100: Fix a data race on s->rts in max3100_work()

[sashiko-bot@kernel.org]

> max3100_set_mctrl() stores the new RTS state and raises s->rts_commit to tell
> max3100_work() that it has to program it:
> 
> 	spin_lock(&s->conf_lock);
> 	if (s->rts != rts) {
> 		s->rts = rts;
> 		s->rts_commit = 1;
> 	}
> 	if (s->loopback_commit || s->rts_commit)
> 		max3100_dowork(s);
> 	spin_unlock(&s->conf_lock);
> 
> max3100_work() consumes s->rts_commit under s->conf_lock, but reads s->rts
> itself outside of the lock, both when it services that pending update and when
> it later transmits a character, so the state it programs into the hardware can
> be stale.
> 
> Read s->rts into a local variable in the s->conf_lock protected snapshot at
> the top of the loop, before s->rts_commit is consumed, in the same way as
> s->conf is read before s->conf_commit.
> 
> Fixes: 7831d56b0a35 ("tty: MAX3100")
> Signed-off-by: Ginger Li <ginger.jzllee@gmail.com>

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

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Sashiko AI review · https://sashiko.dev/#/patchset/20260922170239.33485-1-ginger.jzllee@gmail.com?part=1