Re: [Qemu-devel] [PATCH v5 4/4] Add support for net bridge

[Corey Bryant]

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:
>
> address@hidden:~/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