linux-kernel - Re: [PATCH v3] tty: 8250: fix a missing check for pci_ioremap

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Message-ID: <20190324162904.GH9224@smile.fi.intel.com>
Date:   Sun, 24 Mar 2019 18:29:04 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Aditya Pakki <pakki001@....edu>
Cc:     kjlu@....edu, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, Vinod Koul <vkoul@...nel.org>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] tty: 8250: fix a missing check for pci_ioremap_bar

On Sun, Mar 24, 2019 at 11:09:00AM -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.
Almost, but one think below.

> 
> Signed-off-by: Aditya Pakki <pakki001@....edu>
> 
> ---
> 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 | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_lpss.c b/drivers/tty/serial/8250/8250_lpss.c
> index 53ca9ba6ab4b..7889b2552013 100644
> --- a/drivers/tty/serial/8250/8250_lpss.c
> +++ b/drivers/tty/serial/8250/8250_lpss.c
> @@ -170,9 +170,11 @@ 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);
> @@ -199,6 +201,7 @@ static void qrk_serial_exit_dma(struct lpss8250 *lpss)
>  
>  	if (!param->dma_dev)
>  		return;

> +	pci_iounmap(param->dma_dev, &lpss->dma_chip->regs);

This will fail the DMA driver ->remove() badly.
You need to do this after removal of DMA itself.
See the symmetry with setup above?

>  	dw_dma_remove(&lpss->dma_chip);

...put it here.
Don't forget to separate from above with blank line.

-- 
With Best Regards,
Andy Shevchenko