Re: [PATCH 02/10] HID: hid-lenovo-go-s: Bound stale reply window before reusing send_cmd_complete

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] hid: conflating MCU error with timeout in mcu_property_out()
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commit b76b36bd4347a4e16200e7b5eadeaf196d8595bd
Author: Derek J. Clark <derekjohn.clark@gmail.com>
Subject: HID: hid-lenovo-go-s: Bound stale reply window before reusing send_cmd_complete

This patch mitigates an issue where stale replies to timed-out commands can
silently satisfy the wait for the next command. It introduces a short bounded
wait before reusing the completion structure and tracks when a command has
timed out using a new pending flag.

> diff --git a/drivers/hid/hid-lenovo-go-s.c b/drivers/hid/hid-lenovo-go-s.c
> index 68301d4c762a1..36505d8402ff1 100644
> --- a/drivers/hid/hid-lenovo-go-s.c
> +++ b/drivers/hid/hid-lenovo-go-s.c
> @@ -479,7 +493,9 @@ static int mcu_property_out(struct hid_device *hdev, u8 command, u8 index,
>  							msecs_to_jiffies(timeout));
>  	ret = ret > 0 ? drvdata.cmd_status : ret ?: -EBUSY;
>  
> -	reinit_completion(&drvdata.send_cmd_complete);
> +	if (ret)
> +		drvdata.orphan_ack_pending = true;

[Severity: Low]
Could this logic inadvertently flag a successfully received error reply as an
orphaned timeout?

When the MCU successfully replies with an error code (meaning drvdata.cmd_status
is negative), wait_for_completion_interruptible_timeout() returns a positive
value indicating the wait succeeded. The code then assigns ret =
drvdata.cmd_status, causing the if (ret) check to evaluate to true. 

Since the reply was successfully received and consumed, there doesn't seem to be
an orphaned ACK, but this will set orphan_ack_pending = true and penalize the
next unrelated command with an unnecessary 25ms delay. Is this the intended
behavior, or should it specifically check for the timeout condition instead?

> +
>  	return ret;
>  }
>

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Sashiko AI review · https://sashiko.dev/#/patchset/20260914225303.868569-1-derekjohn.clark@gmail.com?part=2