Re: [PATCH v6] tty: 8250: fix a missing check for pci_ioremap_bar

[Andy Shevchenko]

On Mon, Mar 25, 2019 at 05:21:46PM -0500, Aditya Pakki wrote:
> pci_ioremap_bar could fail. The patch returns in case of failure to
> acquire IOMEM. It also releases the acquired resource in the exit path.

Thanks for an update.
One comment below.

After addressing it, take mine
Reviewed-by: Andy Shevchenko <andriy.shevche...@linux.intel.com>

> 
> Signed-off-by: Aditya Pakki <pakki...@umn.edu>
> 
> ---
> v5: change pci_iounmap to iounmap to pass kbuild errors in other arch
> v4: Missed resource release in dma_probe failure.
> v3: Change the order of pci_iounmap and dw_dma_remove
> v2: Failed to release resource in exit path and incorrect code in non
> DMA case, suggested by Andy Shevchenko
> v1: Missed return by default in CONFIG_SERIAL_8250_DMA, suggested by
> Jiri Slaby
> ---
>  drivers/tty/serial/8250/8250_lpss.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_lpss.c 
> b/drivers/tty/serial/8250/8250_lpss.c
> index 53ca9ba6ab4b..c7c7bf5d7e5e 100644
> --- a/drivers/tty/serial/8250/8250_lpss.c
> +++ b/drivers/tty/serial/8250/8250_lpss.c
> @@ -170,14 +170,18 @@ static void qrk_serial_setup_dma(struct lpss8250 *lpss, 
> struct uart_port *port)
>       int ret;
>  
>       chip->dev = &pdev->dev;
> +     chip->pdata = &qrk_serial_dma_pdata;
>       chip->irq = pci_irq_vector(pdev, 0);
>       chip->regs = pci_ioremap_bar(pdev, 1);
> -     chip->pdata = &qrk_serial_dma_pdata;
> +     if (!chip->regs)
> +             return;
>  
>       /* Falling back to PIO mode if DMA probing fails */
>       ret = dw_dma_probe(chip);
> -     if (ret)
> +     if (ret) {
> +             iounmap(chip->regs);
>               return;
> +     }
>  
>       pci_try_set_mwi(pdev);
>  
> @@ -199,7 +203,10 @@ static void qrk_serial_exit_dma(struct lpss8250 *lpss)
>  
>       if (!param->dma_dev)
>               return;
> +
>       dw_dma_remove(&lpss->dma_chip);
> +
> +     iounmap(&lpss->dma_chip->regs);

This is a bit fragile form of writing. Perhaps

        struct dw_dma_chip *chip = &lpss->dma_chip;

        ...
        dw_dma_remove(chip);

        iounmap(chip->regs);

>  }
>  #else        /* CONFIG_SERIAL_8250_DMA */
>  static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port 
> *port) {}
> -- 
> 2.17.1
> 

-- 
With Best Regards,
Andy Shevchenko