linux-kernel - Re: [PATCH] cvt_fallthrough: A tool to convert /* fallthrough */ comments to fallthrough;

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Message-ID: <576fe2ab-7937-4698-b32a-8599813d6ad1@embeddedor.com>
Date:   Sat, 7 Mar 2020 15:30:07 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Joe Perches <joe@...ches.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Cc:     clang-built-linux@...glegroups.com
Subject: Re: [PATCH] cvt_fallthrough: A tool to convert /* fallthrough */
 comments to fallthrough;



On 2/20/20 14:30, Joe Perches wrote:
> Convert /* fallthrough */ style comments to the pseudo-keyword fallthrough
> to allow clang 10 and higher to work at finding missing fallthroughs too.
> 
> Requires a git repository and overwrites the input files.
> 
> Typical command use:
>     ./scripts/cvt_fallthrough.pl <path|file>
> 
> i.e.:
> 
>    $ ./scripts/cvt_fallthrough.pl block
>      converts all files in block and its subdirectories
>    $ ./scripts/cvt_fallthrough.pl drivers/net/wireless/zydas/zd1201.c
>      converts a single file
> 
> A fallthrough comment with additional comments is converted akin to:
> 
> -		/* fall through - maybe userspace knows this conn_id. */
> +		fallthrough;    /* maybe userspace knows this conn_id */
> 
> A fallthrough comment or fallthrough; between successive case statements
> is deleted.
> 
> e.g.:
> 
>     case FOO:
>     	/* fallthrough */ (or fallthrough;)
>     case BAR:
> 
> is converted to:
> 
>     case FOO:
>     case BAR:
> 

I think the script should only replace the comments and refrain from removing any blank
lines:

--- a/drivers/usb/musb/musb_gadget_ep0.c
+++ b/drivers/usb/musb/musb_gadget_ep0.c
@@ -739,8 +739,7 @@ irqreturn_t musb_g_ep0_irq(struct musb *musb)
                        musb_writeb(mbase, MUSB_TESTMODE,
                                        musb->test_mode_nr);
                }
-               /* FALLTHROUGH */
-
+               fallthrough;
        case MUSB_EP0_STAGE_STATUSOUT:
                /* end of sequence #1: write to host (TX state) */
                {
@@ -771,8 +770,7 @@ irqreturn_t musb_g_ep0_irq(struct musb *musb)
                 */
                retval = IRQ_HANDLED;
                musb->ep0_state = MUSB_EP0_STAGE_SETUP;
-               /* FALLTHROUGH */
-
+               fallthrough;
        case MUSB_EP0_STAGE_SETUP:
 setup:
                if (csr & MUSB_CSR0_RXPKTRDY) {

Some people consistently add blank lines as part of their code style, and if I were
one of those people, I wouldn't like to have such lines removed.

--
Gustavo