linux-kernel - Re: [PATCHv2] ARM: drivers/amba: release the resource to allow for deferred probe

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Date:   Wed, 2 Oct 2019 13:40:43 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Dinh Nguyen <dinguyen@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linus.walleij@...aro.org, p.zabel@...gutronix.de,
        thor.thayer@...ux.intel.com
Subject: Re: [PATCHv2] ARM: drivers/amba: release the resource to allow for
 deferred probe

On Wed, Oct 02, 2019 at 07:33:49AM -0500, Dinh Nguyen wrote:
> With commit "79bdcb202a35 ARM: 8906/1: drivers/amba: add reset control to
> amba bus probe", the amba bus driver needs to be deferred probe because the
> reset driver is probed later. However with a deferred probe, the call to
> request_resource() in the driver returns -EBUSY. The reason is the driver
> has not released the resource from the previous probe attempt.
> 
> This patch fixes how we handle the condition of EPROBE_DEFER that is returned
> from getting the reset controls. For this condition, the patch will jump
> to err_release, which will release the resource.
> 
> Fixes: 79bdcb202a35 ("ARM: 8906/1: drivers/amba: add reset control to
> amba bus probe")
> Signed-off-by: Dinh Nguyen <dinguyen@...nel.org>
> ---
> v2: release the resource when of_reset_control_array_get_optional_shared()
>     returns EPROBE_DEFER
> ---
>  drivers/amba/bus.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index f39f075abff9..1109437815eb 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -409,9 +409,12 @@ static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
>  		 */
>  		rstc = of_reset_control_array_get_optional_shared(dev->dev.of_node);
>  		if (IS_ERR(rstc)) {
> -			if (PTR_ERR(rstc) != -EPROBE_DEFER)
> +			ret = PTR_ERR(rstc);
> +			if (ret == -EPROBE_DEFER)
> +				goto err_release;
> +			else
>  				dev_err(&dev->dev, "Can't get amba reset!\n");
> -			return PTR_ERR(rstc);
> +			return ret;

Still a negative.

Remember in the comments to the previous patch I talked about ioremap().

Please read the code that you are modifying and carefully consider what
needs to happen at this site to properly clean up on failure.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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