linux-kernel - Re: [PATCH] usb: phy: ab8500-usb: Mark expected switch fall-throughs

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Date:   Mon, 29 Jul 2019 09:36:40 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [PATCH] usb: phy: ab8500-usb: Mark expected switch fall-throughs

On Sun, Jul 28, 2019 at 07:06:31PM -0500, Gustavo A. R. Silva wrote:
> Mark switch cases where we are expecting to fall through.
> 
> This patch fixes the following warnings:
> 
> drivers/usb/phy/phy-ab8500-usb.c: In function 'ab8500_usb_link_status_update':
> drivers/usb/phy/phy-ab8500-usb.c:424:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    event = UX500_MUSB_RIDB;
>    ~~~~~~^~~~~~~~~~~~~~~~~
> drivers/usb/phy/phy-ab8500-usb.c:425:2: note: here
>   case USB_LINK_NOT_CONFIGURED_8500:
>   ^~~~
> drivers/usb/phy/phy-ab8500-usb.c:440:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    event = UX500_MUSB_RIDC;
>    ~~~~~~^~~~~~~~~~~~~~~~~
> drivers/usb/phy/phy-ab8500-usb.c:441:2: note: here
>   case USB_LINK_STD_HOST_NC_8500:
>   ^~~~
> drivers/usb/phy/phy-ab8500-usb.c:459:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    event = UX500_MUSB_RIDA;
>    ~~~~~~^~~~~~~~~~~~~~~~~
> drivers/usb/phy/phy-ab8500-usb.c:460:2: note: here
>   case USB_LINK_HM_IDGND_8500:
>   ^~~~
> drivers/usb/phy/phy-ab8500-usb.c: In function 'ab8505_usb_link_status_update':
> drivers/usb/phy/phy-ab8500-usb.c:332:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    event = UX500_MUSB_RIDB;
>    ~~~~~~^~~~~~~~~~~~~~~~~
> drivers/usb/phy/phy-ab8500-usb.c:333:2: note: here
>   case USB_LINK_NOT_CONFIGURED_8505:
>   ^~~~
> drivers/usb/phy/phy-ab8500-usb.c:352:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    event = UX500_MUSB_RIDC;
>    ~~~~~~^~~~~~~~~~~~~~~~~
> drivers/usb/phy/phy-ab8500-usb.c:353:2: note: here
>   case USB_LINK_STD_HOST_NC_8505:
>   ^~~~
> drivers/usb/phy/phy-ab8500-usb.c:370:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    event = UX500_MUSB_RIDA;
>    ~~~~~~^~~~~~~~~~~~~~~~~
> drivers/usb/phy/phy-ab8500-usb.c:371:2: note: here
>   case USB_LINK_HM_IDGND_8505:
>   ^~~~
> 
> Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  drivers/usb/phy/phy-ab8500-usb.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/usb/phy/phy-ab8500-usb.c b/drivers/usb/phy/phy-ab8500-usb.c
> index aaf363f19714..14b432982fd3 100644
> --- a/drivers/usb/phy/phy-ab8500-usb.c
> +++ b/drivers/usb/phy/phy-ab8500-usb.c
> @@ -330,6 +330,7 @@ static int ab8505_usb_link_status_update(struct ab8500_usb *ab,
>  	switch (lsts) {
>  	case USB_LINK_ACA_RID_B_8505:
>  		event = UX500_MUSB_RIDB;
> +		/* Fall through */
>  	case USB_LINK_NOT_CONFIGURED_8505:
>  	case USB_LINK_RESERVED0_8505:
>  	case USB_LINK_RESERVED1_8505:
> @@ -350,6 +351,7 @@ static int ab8505_usb_link_status_update(struct ab8500_usb *ab,
>  
>  	case USB_LINK_ACA_RID_C_NM_8505:
>  		event = UX500_MUSB_RIDC;
> +		/* Fall through */
>  	case USB_LINK_STD_HOST_NC_8505:
>  	case USB_LINK_STD_HOST_C_NS_8505:
>  	case USB_LINK_STD_HOST_C_S_8505:
> @@ -368,6 +370,7 @@ static int ab8505_usb_link_status_update(struct ab8500_usb *ab,
>  	case USB_LINK_ACA_RID_A_8505:
>  	case USB_LINK_ACA_DOCK_CHGR_8505:
>  		event = UX500_MUSB_RIDA;
> +		/* Fall through */
>  	case USB_LINK_HM_IDGND_8505:
>  		if (ab->mode == USB_IDLE) {
>  			ab->mode = USB_HOST;
> @@ -422,6 +425,7 @@ static int ab8500_usb_link_status_update(struct ab8500_usb *ab,
>  	switch (lsts) {
>  	case USB_LINK_ACA_RID_B_8500:
>  		event = UX500_MUSB_RIDB;
> +		/* Fall through */
>  	case USB_LINK_NOT_CONFIGURED_8500:
>  	case USB_LINK_NOT_VALID_LINK_8500:
>  		ab->mode = USB_IDLE;
> @@ -438,6 +442,7 @@ static int ab8500_usb_link_status_update(struct ab8500_usb *ab,
>  	case USB_LINK_ACA_RID_C_HS_8500:
>  	case USB_LINK_ACA_RID_C_HS_CHIRP_8500:
>  		event = UX500_MUSB_RIDC;
> +		/* Fall through */
>  	case USB_LINK_STD_HOST_NC_8500:
>  	case USB_LINK_STD_HOST_C_NS_8500:
>  	case USB_LINK_STD_HOST_C_S_8500:
> @@ -457,6 +462,7 @@ static int ab8500_usb_link_status_update(struct ab8500_usb *ab,
>  
>  	case USB_LINK_ACA_RID_A_8500:
>  		event = UX500_MUSB_RIDA;
> +		/* Fall through */
>  	case USB_LINK_HM_IDGND_8500:
>  		if (ab->mode == USB_IDLE) {
>  			ab->mode = USB_HOST;
> -- 
> 2.22.0
> 

-- 
Kees Cook