Re: [PATCH 1/7] Input: gscps2 - clean up driver code style and structure

[sashiko-bot@kernel.org]

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

Pre-existing issues:
- [High] The busy-wait loop in `gscps2_writeb_output` polling the hardware status register lacks a timeout, creating a hard lockup (deadlock) risk when invoked with local interrupts disabled.
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commit edfe57337208b53162446f9db3e046a15ffe59af
Author: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: gscps2 - clean up driver code style and structure

This commit cleans up code style and function ordering in the gscps2 driver.
It updates macro definitions, replaces printk with dev_dbg, and introduces
cpu_relax() into the spin-wait loops.

> diff --git a/drivers/input/serio/gscps2.c b/drivers/input/serio/gscps2.c
> index 43453ec533b22..b82c56ba8ff70 100644
> --- a/drivers/input/serio/gscps2.c
> +++ b/drivers/input/serio/gscps2.c

[ ... ]

> +/*
> + * gscps2_writeb_output() - write a byte to the port
> + *
> + * returns 1 on success, 0 on error
> + */
> +static inline int gscps2_writeb_output(struct gscps2port *ps2port, u8 data)
> +{
> +	char __iomem *addr = ps2port->addr;
> +
> +	if (!wait_TBE(addr)) {
> +		dev_dbg(&ps2port->padev->dev, "timeout - could not write byte %#x\n", data);
> +		return 0;
> +	}
> +
> +	while (gscps2_readb_status(addr) & GSC_STAT_RBNE)
> +		cpu_relax();

[Severity: High]
This is a pre-existing issue, but does this busy-wait loop risk a hard CPU
lockup when invoked with local interrupts disabled?

A PS/2 driver like atkbd can call serio_write() from an interrupt context
with local IRQs disabled (for example, in atkbd_interrupt sending
ATKBD_CMD_RESEND in response to a parity error).

If a new byte arrives in the receive buffer concurrently, the GSC_STAT_RBNE
bit is set. Since local IRQs are disabled, the hardware interrupt handler
cannot run to read the pending byte. This means GSC_STAT_RBNE will never
clear and the CPU could hang indefinitely waiting for the buffer to empty.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260830-gscps2-v1-0-c733d4cae7f9@gmail.com?part=1