Re: [Qemu-trivial] [Qemu-devel] [PATCH] Add 'fall through' comments to case statements without break

[andrzej zaborowski]

On 10 January 2012 09:35, Stefan Hajnoczi <address@hidden> wrote:
> 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 <address@hidden>
>> ---
>>  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?

Yes, definitely there's a break missing.  Bluetooth SCO links are like
USB Isochronous, so not really tested because they're only used by
streaming devices.

Cheers