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Re: [Qemu-devel] [PATCH v2] net: Flush queued packets when guest resumes
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [PATCH v2] net: Flush queued packets when guest resumes |
Date: |
Tue, 7 Jul 2015 17:03:58 +0800 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Tue, 07/07 15:44, Jason Wang wrote:
>
>
> On 07/07/2015 09:21 AM, Fam Zheng wrote:
> > Since commit 6e99c63 "net/socket: Drop net_socket_can_send" and friends,
> > net queues need to be explicitly flushed after qemu_can_send_packet()
> > returns false, because the netdev side will disable the polling of fd.
> >
> > This fixes the case of "cont" after "stop" (or migration).
> >
> > Signed-off-by: Fam Zheng <address@hidden>
> >
> > ---
> >
> > v2: Unify with VM stop handler. (Stefan)
> > ---
> > net/net.c | 19 ++++++++++++-------
> > 1 file changed, 12 insertions(+), 7 deletions(-)
> >
> > diff --git a/net/net.c b/net/net.c
> > index 6ff7fec..28a5597 100644
> > --- a/net/net.c
> > +++ b/net/net.c
> > @@ -1257,14 +1257,19 @@ void qmp_set_link(const char *name, bool up, Error
> > **errp)
> > static void net_vm_change_state_handler(void *opaque, int running,
> > RunState state)
> > {
> > - /* Complete all queued packets, to guarantee we don't modify
> > - * state later when VM is not running.
> > - */
> > - if (!running) {
> > - NetClientState *nc;
> > - NetClientState *tmp;
> > + NetClientState *nc;
> > + NetClientState *tmp;
> >
> > - QTAILQ_FOREACH_SAFE(nc, &net_clients, next, tmp) {
> > + QTAILQ_FOREACH_SAFE(nc, &net_clients, next, tmp) {
> > + if (running) {
> > + /* Flush queued packets and wake up backends. */
> > + if (nc->peer && qemu_can_send_packet(nc)) {
> > + qemu_flush_queued_packets(nc->peer);
> > + }
> > + } else {
> > + /* Complete all queued packets, to guarantee we don't modify
> > + * state later when VM is not running.
> > + */
> > qemu_flush_or_purge_queued_packets(nc, true);
> > }
>
> Looks like qemu_can_send_packet() checks both nc->peer and runstate. So
> probably, we can simplify this to:
>
> if (qemu_can_send_packet(nc))
> qemu_flush_queued_packets(nc->peer);
> else
> qemu_flush_or_purge_queued_packets(nc, true);
>
> > }
>
qemu_can_send_packet returns 1 if !nc->peer, so this doesn't work.
Fam