linux-kernel - Re: [PATCH v3] usb: dwc2: dwc2_vbus_supply

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Message-ID: <1794463.c121CNJ3R4@diego>
Date:   Thu, 22 Mar 2018 14:26:34 +0100
From:   Heiko Stübner <heiko@...ech.de>
To:     Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:     linux-kernel@...r.kernel.org,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Amelie Delaunay <amelie.delaunay@...com>,
        Minas Harutyunyan <hminas@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH v3] usb: dwc2: dwc2_vbus_supply_init: fix error check

Am Donnerstag, 22. März 2018, 14:14:51 CET schrieb Tomeu Vizoso:
> devm_regulator_get_optional returns -ENODEV if the regulator isn't
> there, so if that's the case we have to make sure not to leave -ENODEV
> in the regulator pointer.
> 
> Also, make sure we return 0 in that case, but correctly propagate any
> other errors. Also propagate the error from _dwc2_hcd_start.
> 
> Fixes: 531ef5ebea96 ("usb: dwc2: add support for host mode external vbus
> supply") Cc: Amelie Delaunay <amelie.delaunay@...com>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
> 
> ---
> 
> v2: Only overwrite the error in the pointer after checking it (Heiko
>     Stübner <heiko@...ech.de>)
> v3: Remove hunks that shouldn't be in this patch
> ---
>  drivers/usb/dwc2/hcd.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
> index dcfda5eb4cac..863aed20517f 100644
> --- a/drivers/usb/dwc2/hcd.c
> +++ b/drivers/usb/dwc2/hcd.c
> @@ -359,8 +359,13 @@ static void dwc2_gusbcfg_init(struct dwc2_hsotg *hsotg)
> static int dwc2_vbus_supply_init(struct dwc2_hsotg *hsotg)
>  {
>  	hsotg->vbus_supply = devm_regulator_get_optional(hsotg->dev, "vbus");
> -	if (IS_ERR(hsotg->vbus_supply))
> +	if (PTR_ERR(hsotg->vbus_supply) == -ENODEV) {
> +		hsotg->vbus_supply = NULL;
>  		return 0;
> +	} else if (IS_ERR(hsotg->vbus_supply)) {
> +		hsotg->vbus_supply = NULL;
> +		return PTR_ERR(hsotg->vbus_supply);
> +	}

my personal cluelessnes, but can you use PTR_ERR without checking for
IS_ERR first?

I would've expected something along the line of

if (IS_ERR(hsotg->vbus_supply)) {
	if (PTR_ERR(hsotg->vbus_supply) == -ENODEV) {
		hsotg->vbus_supply = NULL;
		return 0;
	} else {
		return PTR_ERR(hsotg->vbus_supply);
	}
}