linux-kernel - RE: [PATCH] usb: renesas_usbhs: fix signed-unsigned return

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Message-ID: <SG2PR06MB0919683D1A847AD697F6E725D8970@SG2PR06MB0919.apcprd06.prod.outlook.com>
Date:	Thu, 14 Apr 2016 10:52:20 +0000
From:	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
To:	Sudip Mukherjee <sudipm.mukherjee@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Felipe Balbi <balbi@...nel.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: RE: [PATCH] usb: renesas_usbhs: fix signed-unsigned return

Hi,

> From: Sudip Mukherjee
> Sent: Saturday, April 09, 2016 12:05 AM
> 
> The return type of usbhsp_setup_pipecfg() was u16 but it was returning
> a negative value (-EINVAL). Instead lets return a pointer to u16 which
> will hold the value to be returned or in case of error, return the
> error code in ERR_PTR.

Thank you for the patch!
I also think this usbhsp_setup_pipecfg() should return error code using correct variable type.

However, I would like to avoid to use ERR_PTR and kmalloc() somehow because
I feel this patch is complex a little.
How about the usbhsp_setup_pipecfg() prototype is changed like the following?

static int usbhsp_setup_pipecfg(struct usbhs_pipe *pipe,
				int is_host, int dir_in, u16 *pipecfg);

Best regards,
Yoshihiro Shimoda

> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>
> ---
>  drivers/usb/renesas_usbhs/pipe.c | 38 +++++++++++++++++++++++++-------------
>  1 file changed, 25 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/usb/renesas_usbhs/pipe.c b/drivers/usb/renesas_usbhs/pipe.c
> index 78e9dba..00d595c 100644
> --- a/drivers/usb/renesas_usbhs/pipe.c
> +++ b/drivers/usb/renesas_usbhs/pipe.c
> @@ -391,9 +391,9 @@ void usbhs_pipe_set_trans_count_if_bulk(struct usbhs_pipe *pipe, int len)
>  /*
>   *		pipe setup
>   */
> -static u16 usbhsp_setup_pipecfg(struct usbhs_pipe *pipe,
> -				int is_host,
> -				int dir_in)
> +static u16 *usbhsp_setup_pipecfg(struct usbhs_pipe *pipe,
> +				 int is_host,
> +				 int dir_in)
>  {
>  	u16 type = 0;
>  	u16 bfre = 0;
> @@ -407,9 +407,13 @@ static u16 usbhsp_setup_pipecfg(struct usbhs_pipe *pipe,
>  		[USB_ENDPOINT_XFER_INT]  = TYPE_INT,
>  		[USB_ENDPOINT_XFER_ISOC] = TYPE_ISO,
>  	};
> +	u16 *result;
> 
>  	if (usbhs_pipe_is_dcp(pipe))
> -		return -EINVAL;
> +		return ERR_PTR(-EINVAL);
> +	result = kmalloc(sizeof(u16), GFP_KERNEL);
> +	if (!result)
> +		return ERR_PTR(-ENOMEM);
> 
>  	/*
>  	 * PIPECFG
> @@ -451,14 +455,14 @@ static u16 usbhsp_setup_pipecfg(struct usbhs_pipe *pipe,
> 
>  	/* EPNUM */
>  	epnum = 0; /* see usbhs_pipe_config_update() */
> -
> -	return	type	|
> -		bfre	|
> -		dblb	|
> -		cntmd	|
> -		dir	|
> -		shtnak	|
> -		epnum;
> +	*result = type	 |
> +		  bfre	 |
> +		  dblb	 |
> +		  cntmd	 |
> +		  dir	 |
> +		  shtnak |
> +		  epnum;
> +	return result;
>  }
> 
>  static u16 usbhsp_setup_pipebuff(struct usbhs_pipe *pipe)
> @@ -683,6 +687,7 @@ struct usbhs_pipe *usbhs_pipe_malloc(struct usbhs_priv *priv,
>  	int is_host = usbhs_mod_is_host(priv);
>  	int ret;
>  	u16 pipecfg, pipebuf;
> +	u16 *result;
> 
>  	pipe = usbhsp_get_pipe(priv, endpoint_type);
>  	if (!pipe) {
> @@ -702,7 +707,14 @@ struct usbhs_pipe *usbhs_pipe_malloc(struct usbhs_priv *priv,
>  		return NULL;
>  	}
> 
> -	pipecfg  = usbhsp_setup_pipecfg(pipe, is_host, dir_in);
> +	result = usbhsp_setup_pipecfg(pipe, is_host, dir_in);
> +	if (IS_ERR(result)) {
> +		dev_err(dev, "can't setup pipe\n");
> +		return NULL;
> +	}
> +	pipecfg = *result;
> +	kfree(result);
> +
>  	pipebuf  = usbhsp_setup_pipebuff(pipe);
> 
>  	usbhsp_pipe_select(pipe);
> --
> 1.9.1
> 
> --
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