[Qemu-devel] [PATCH] libvhost-user: implement VHOST_USER_PROTOCOL_F_REPLY_ACK

[Qemu-devel] [PATCH] libvhost-user: implement VHOST_USER_PROTOCOL_F_REPLY_ACK

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

This is really simple, since we know whether a response is
already requested or not, so we can just send a (successful)
response when there isn't one already.

Given that, it's not all _that_ useful but the master can at
least be sure the message was processed, and we can exercise
more code paths using the example code.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 contrib/libvhost-user/libvhost-user.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index 4b36e35a82f8..010ddb9c0f42 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -1164,7 +1164,8 @@ vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg)
                         1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD |
                         1ULL << VHOST_USER_PROTOCOL_F_SLAVE_REQ |
                         1ULL << VHOST_USER_PROTOCOL_F_HOST_NOTIFIER |
-                        1ULL << VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD;
+                        1ULL << VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD |
+                        1ULL << VHOST_USER_PROTOCOL_F_REPLY_ACK;
 
     if (have_userfault()) {
         features |= 1ULL << VHOST_USER_PROTOCOL_F_PAGEFAULT;
@@ -1546,13 +1547,20 @@ vu_dispatch(VuDev *dev)
 {
     VhostUserMsg vmsg = { 0, };
     int reply_requested;
-    bool success = false;
+    bool need_reply, success = false;
 
     if (!vu_message_read(dev, dev->sock, &vmsg)) {
         goto end;
     }
 
+    need_reply = vmsg.flags & VHOST_USER_NEED_REPLY_MASK;
+
     reply_requested = vu_process_message(dev, &vmsg);
+    if (!reply_requested && need_reply) {
+        vmsg_set_reply_u64(&vmsg, 0);
+        reply_requested = 1;
+    }
+
     if (!reply_requested) {
         success = true;
         goto end;
-- 
2.23.0

Re: [Qemu-devel] [PATCH] libvhost-user: implement VHOST_USER_PROTOCOL_F_REPLY_ACK

[Stefan Hajnoczi]

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On Tue, Sep 03, 2019 at 10:25:05PM +0300, Johannes Berg wrote:
> From: Johannes Berg <johannes.berg@intel.com>
> 
> This is really simple, since we know whether a response is
> already requested or not, so we can just send a (successful)
> response when there isn't one already.
> 
> Given that, it's not all _that_ useful but the master can at
> least be sure the message was processed, and we can exercise
> more code paths using the example code.
> 
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
> ---
>  contrib/libvhost-user/libvhost-user.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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