linux-kernel - Re: [PATCH] scsi: st: Add missing break in switch statement in st

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Message-ID: <7843ce6b-92ae-7b6c-1fc-acb0ffe2bbc0@linux-m68k.org>
Date:   Wed, 18 Aug 2021 10:54:06 +1000 (AEST)
From:   Finn Thain <fthain@...ux-m68k.org>
To:     Nathan Chancellor <nathan@...nel.org>
cc:     Kai Mäkisara <Kai.Makisara@...umbus.fi>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH] scsi: st: Add missing break in switch statement in
 st_ioctl()

On Tue, 17 Aug 2021, Nathan Chancellor wrote:

> Clang + -Wimplicit-fallthrough warns:
> 
> drivers/scsi/st.c:3831:2: warning: unannotated fall-through between
> switch labels [-Wimplicit-fallthrough]
>         default:
>         ^
> drivers/scsi/st.c:3831:2: note: insert 'break;' to avoid fall-through
>         default:
>         ^
>         break;
> 1 warning generated.
> 
> Clang's -Wimplicit-fallthrough is a little bit more pedantic than GCC's,
> requiring every case block to end in break, return, or fallthrough,
> rather than allowing implicit fallthroughs to cases that just contain
> break or return. Add a break so that there is no more warning, as has
> been done all over the tree already.
> 
> Fixes: 2e27f576abc6 ("scsi: scsi_ioctl: Call scsi_cmd_ioctl() from scsi_ioctl()")
> Signed-off-by: Nathan Chancellor <nathan@...nel.org>
> ---
>  drivers/scsi/st.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
> index 2d1b0594af69..0e36a36ed24d 100644
> --- a/drivers/scsi/st.c
> +++ b/drivers/scsi/st.c
> @@ -3828,6 +3828,7 @@ static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
>  	case CDROM_SEND_PACKET:
>  		if (!capable(CAP_SYS_RAWIO))
>  			return -EPERM;
> +		break;
>  	default:
>  		break;
>  	}
> 
> base-commit: 58dd8f6e1cf8c47e81fbec9f47099772ab75278b
> 

Well, that sure is ugly.

Do you think the following change would cause any static checkers to spit 
their dummys and throw their toys out of the pram?

@@ -3828,6 +3828,7 @@ static long st_ioctl(struct file *file, unsigned int cmd_in, unsigned long arg)
 	case CDROM_SEND_PACKET:
 		if (!capable(CAP_SYS_RAWIO))
 			return -EPERM;
+		break;
-	default:
-		break;
 	}