Re: [PATCH v2 4/5] iio: light: stk3310: add per-chip match data

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] stk3310_write_event() modifies hardware registers and shared cached state without holding the driver lock, leading to state desynchronization.
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commit 1a4ec350350bbed28440d2daf132d19b8c5712c9
Author: Jorijn van der Graaf <jorijnvdgraaf@catcrafts.net>

    iio: light: stk3310: add per-chip match data
    
    Introduce a chip_info structure carrying the device name and channel
    specification, attach it to every i2c, OF and ACPI table entry, and
    let probe take it from the match data, failing when there is none.

> diff --git a/drivers/iio/light/stk3310.c b/drivers/iio/light/stk3310.c
> index 156888969366c..d632e6447f065 100644
> --- a/drivers/iio/light/stk3310.c
> +++ b/drivers/iio/light/stk3310.c

[Severity: High]
This is a pre-existing issue, but does stk3310_write_event() need to hold
data->lock to prevent concurrent access?

Looking at stk3310_write_event(), it modifies hardware registers and shared
cached state without holding the driver lock:

	ret = regmap_bulk_write(data->regmap, reg, &buf, sizeof(buf));
	if (ret < 0) {
		dev_err(&client->dev, "failed to set PS threshold!\n");
		return ret;
	}

	if (reg == STK3310_REG_THDH_PS)
		data->ps_thdh = val;
	else
		data->ps_thdl = val;

This allows a race between concurrent writers to cause a state
desynchronization between the hardware registers and the driver's cached
threshold values (data->ps_thdh and data->ps_thdl).

On system resume, the driver restores these incorrect cached thresholds to the
hardware, resulting in incorrect proximity event behavior.

Additionally, this function reads state that could concurrently be modified by
stk3310_write_raw() without a lock:

	ret = regmap_field_read(data->reg_ps_gain, &index);

This causes a TOCTOU race on threshold bounds checking.

Could we add a mutex_lock() to stk3310_write_event() to synchronize with
stk3310_write_raw() and prevent state desynchronization?

[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260826175409.326131-1-jorijnvdgraaf@catcrafts.net?part=4