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Date: Thu, 15 Dec 2011 23:00:24 -0500
From: Corey Bryant <coreyb@linux.vnet.ibm.com>
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Subject: Re: [Qemu-devel] [PATCH v5 4/4] Add support for net bridge
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To: Anthony Liguori <aliguori@us.ibm.com>
Cc: rmarwah@linux.vnet.ibm.com, qemu-devel@nongnu.org



On 12/15/2011 10:26 AM, Anthony Liguori wrote:
> On 11/13/2011 09:45 PM, Corey Bryant wrote:
>> The most common use of -net tap is to connect a tap device to a
>> bridge. This
>> requires the use of a script and running qemu as root in order to
>> allocate a
>> tap device to pass to the script.
>
> This patch breaks the build:
>
> anthony@titi:~/build/qemu$ make
> CC net/tap.o
> cc1: warnings being treated as errors
> /home/anthony/git/qemu/net/tap.c: In function ‘net_init_tap’:
> /home/anthony/git/qemu/net/tap.c:560:15: error: ‘s’ may be used
> uninitialized in this function
> make: *** [net/tap.o] Error 1
>

I was wondering how I missed this.  I typically configure with 
--enable-debug, which appears to suppress warnings.

>>
>> - s = net_tap_fd_init(vlan, "tap", name, fd, vnet_hdr);
>> - if (!s) {
>> - close(fd);
>> - return -1;
>> + s = net_tap_fd_init(vlan, "tap", name, fd, vnet_hdr);
>> + if (!s) {
>> + close(fd);
>> + return -1;
>> + }
>> }
>
> And indeed, you've changed the function from unconditionally
> initializing s to conditionally initializing it. Specifically, you've
> broken -net tap,fd=X which would break tools like libvirt.
>
> Regards,
>
> Anthony Liguori
>
>

-- 
Regards,
Corey