Re: [PATCH 1/3] serial: 8250_lpss: do not touch uninitialized line in ehl_serial_exit()

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

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On Fri, 9 Oct 2026, Jiri Slaby (SUSE) wrote:

> lpss8250_probe() calls lpss->board->exit() on its error path. For the
> EHL board, that is ehl_serial_exit() and it does:
> serial8250_get_port(lpss->data.line)->dma = NULL;
> 
> But when lpss8250_dma_setup() or serial8250_register_8250_port() fails,
> lpss->data.line was never assigned. As lpss is kzalloc()ed, line is 0
> and ehl_serial_exit() clears the dma pointer of an unrelated port --
> serial8250_ports[0], i.e. ttyS0, which is often the console.
> 
> Initialize lpss->data.line to -1 in probe and skip the clearing in
> ehl_serial_exit() if no port was registered.
> 
> Fixes: 5318f70da7e8 ("serial: 8250_lpss: Balance reference count for PCI DMA device")
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
> Assisted-by: LLM
> --
> Cc: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: linux-serial@vger.kernel.org
> ---
>  drivers/tty/serial/8250/8250_lpss.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/tty/serial/8250/8250_lpss.c b/drivers/tty/serial/8250/8250_lpss.c
> index 776ec1ef29d6..c5257847a94c 100644
> --- a/drivers/tty/serial/8250/8250_lpss.c
> +++ b/drivers/tty/serial/8250/8250_lpss.c
> @@ -183,6 +183,9 @@ static int ehl_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
>  
>  static void ehl_serial_exit(struct lpss8250 *lpss)
>  {
> +	if (lpss->data.line < 0)
> +		return;
> +
>  	struct uart_8250_port *up = serial8250_get_port(lpss->data.line);

Declaration now ends up mid-function for a non-cleanup variable so this 
should be split to two lines.

>  
>  	up->dma = NULL;
> @@ -329,6 +332,8 @@ static int lpss8250_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  		return ret;
>  
>  	lpss->board = (struct lpss8250_board *)id->driver_data;
> +	/* for tests in lpss->board->exit() */
> +	lpss->data.line = -1;
>  
>  	memset(&uart, 0, sizeof(struct uart_8250_port));
>  
> 

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 i.