Re: [Qemu-devel] [PATCH v2 1/2] net: assert that tx packets have nonzero size

[Alexander Bulekov]

On 191107 1221, Jason Wang wrote:
> 
> On 2019/7/22 下午9:24, Oleinik, Alexander wrote:
> > Virtual devices should not try to send zero-sized packets. The caller
> > should check the size prior to calling qemu_sendv_packet_async.
> > 
> > Signed-off-by: Alexander Oleinik <address@hidden>
> > ---
> > v2:
> >    * Improve the comment to explain the rationale for adding the assert.
> >   net/net.c | 9 +++++++++
> >   1 file changed, 9 insertions(+)
> > 
> > diff --git a/net/net.c b/net/net.c
> > index 7d4098254f..4ad21df36f 100644
> > --- a/net/net.c
> > +++ b/net/net.c
> > @@ -741,6 +741,15 @@ ssize_t qemu_sendv_packet_async(NetClientState *sender,
> >       size_t size = iov_size(iov, iovcnt);
> >       int ret;
> > +    /*
> > +     * Since this function returns the size of the sent packets, and a 
> > return
> > +     * value of zero indicates that the packet will be sent asynchronously,
> > +     * there is currently no way to report that a 0-sized packet has been 
> > sent
> > +     * successfully. Forbid it for now, and if someone needs this 
> > functionality
> > +     * later, the API will require a change.
> > +     */
> > +    assert(size);
> 
> 
> This probably will make the assertion triggerable from guest. Is this better
> to warn and return NET_BUFSIZE + 1 here?

Will do. I'll send a v3 out with this change.
Thank you

> Thanks
> 
> 
> > +
> >       if (size > NET_BUFSIZE) {
> >           return size;
> >       }
>