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Date: Tue, 10 Jan 2012 08:35:55 +0000
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20120110083555.GA13145@stefanha-thinkpad.localdomain>
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Subject: Re: [Qemu-devel] [Qemu-trivial] [PATCH] Add 'fall through' comments
 to case statements without break
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To: Stefan Weil <sw@weilnetz.de>
Cc: qemu-trivial@nongnu.org, qemu-devel@nongnu.org

On Mon, Jan 09, 2012 at 06:29:51PM +0100, Stefan Weil wrote:
> These comments are used by static code analysis tools and in code reviews
> to avoid false warnings because of missing break statements.
> 
> The case statements handled here were reported by coverity.
> 
> Signed-off-by: Stefan Weil <sw@weilnetz.de>
> ---
>  hw/pcnet.c    |    1 +
>  json-lexer.c  |    1 +
>  qemu-option.c |    4 ++++
>  3 files changed, 6 insertions(+), 0 deletions(-)

This reminds me of another questionable fall-through:

bt-host.c:bt_host_read():

while (s->len --)
    switch (*pkt ++) {
    ...
    case HCI_SCODATA_PKT:
        if (s->len < 3)
            goto bad_pkt;

        pktlen = MIN(pkt[2] + 3, s->len);
        s->len -= pktlen;
        pkt += pktlen;
                             <--- fall-through or not?
    default:
    bad_pkt:
        fprintf(stderr, "qemu: bad HCI packet type %02x\n", pkt[-1]);
    }

It seems the code will skip HCI_SCODATA_PKT and report a warning (although type
pkt[-1] will be incorrect).  Any thoughts?

Stefan