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Date: Thu, 15 Dec 2011 09:26:55 -0600
From: Anthony Liguori <aliguori@us.ibm.com>
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Subject: Re: [Qemu-devel] [PATCH v5 4/4] Add support for net bridge
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To: Corey Bryant <coreyb@linux.vnet.ibm.com>
Cc: rmarwah@linux.vnet.ibm.com, qemu-devel@nongnu.org

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

>
> -    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