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From: Dan Williams <dan.j.williams@intel.com>
To: trix@redhat.com
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Subject: Re: [RFC] treewide: cleanup unreachable breaks
Date: Sat, 17 Oct 2020 14:01:22 -0700
Message-ID: <CAPcyv4jkSFxMXgMABX7sDbwmq8zJO=rLX2ww3Y9Tc0VAANY8xQ@mail.gmail.com> (raw)
In-Reply-To: <20201017160928.12698-1-trix@redhat.com>

On Sat, Oct 17, 2020 at 9:10 AM <trix@redhat.com> wrote:
>
> From: Tom Rix <trix@redhat.com>
>
> This is a upcoming change to clean up a new warning treewide.
> I am wondering if the change could be one mega patch (see below) or
> normal patch per file about 100 patches or somewhere half way by collecting
> early acks.
>
> clang has a number of useful, new warnings see
> https://clang.llvm.org/docs/DiagnosticsReference.html
>
> This change cleans up -Wunreachable-code-break
> https://clang.llvm.org/docs/DiagnosticsReference.html#wunreachable-code-break
> for 266 of 485 warnings in this week's linux-next, allyesconfig on x86_64.
>
> The method of fixing was to look for warnings where the preceding statement
> was a simple statement and by inspection made the subsequent break unneeded.
> In order of frequency these look like
>
> return and break
>
>         switch (c->x86_vendor) {
>         case X86_VENDOR_INTEL:
>                 intel_p5_mcheck_init(c);
>                 return 1;
> -               break;
>
> goto and break
>
>         default:
>                 operation = 0; /* make gcc happy */
>                 goto fail_response;
> -               break;
>
> break and break
>                 case COLOR_SPACE_SRGB:
>                         /* by pass */
>                         REG_SET(OUTPUT_CSC_CONTROL, 0,
>                                 OUTPUT_CSC_GRPH_MODE, 0);
>                         break;
> -                       break;
>
> The exception to the simple statement, is a switch case with a block
> and the end of block is a return
>
>                         struct obj_buffer *buff = r->ptr;
>                         return scnprintf(str, PRIV_STR_SIZE,
>                                         "size=%u\naddr=0x%X\n", buff->size,
>                                         buff->addr);
>                 }
> -               break;
>
> Not considered obvious and excluded, breaks after
> multi level switches
> complicated if-else if-else blocks
> panic() or similar calls
>
> And there is an odd addition of a 'fallthrough' in drivers/tty/nozomi.c
[..]
> diff --git a/drivers/nvdimm/claim.c b/drivers/nvdimm/claim.c
> index 5a7c80053c62..2f250874b1a4 100644
> --- a/drivers/nvdimm/claim.c
> +++ b/drivers/nvdimm/claim.c
> @@ -200,11 +200,10 @@ ssize_t nd_namespace_store(struct device *dev,
>                 }
>                 break;
>         default:
>                 len = -EBUSY;
>                 goto out_attach;
> -               break;
>         }

Acked-by: Dan Williams <dan.j.williams@intel.com>

  parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-17 16:09 trix
2020-10-17 16:24 ` Joe Perches
2020-10-17 18:21   ` [Cocci] " Julia Lawall
2020-10-17 19:00     ` Joe Perches
2020-10-17 21:01 ` Dan Williams [this message]
2020-10-18  5:43 ` Greg KH
2020-10-18 14:04   ` Tom Rix
2020-10-19 19:42   ` Nick Desaulniers
2020-10-19 23:05     ` Jason Gunthorpe
2020-10-20 14:09       ` Tom Rix
2020-10-20  8:47     ` [Ocfs2-devel] " John Haxby
2020-10-20 13:55     ` Tom Rix
2020-10-20 18:42     ` Joe Perches
2020-10-18  9:29 ` Hans de Goede
2020-10-18 18:59 ` [Ocfs2-devel] " Matthew Wilcox
2020-10-18 19:06   ` Joe Perches
2020-10-18 19:13   ` James Bottomley
2020-10-18 19:16     ` Matthew Wilcox
2020-10-18 19:17       ` James Bottomley

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