[Qemu-devel] libvhost-user: Fix the VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD check

[Boeuf, Sebastien]

From 0a53a81db6dd069f9b7bcdcd386845bceb3a2ac6 Mon Sep 17 00:00:00 2001
From: Sebastien Boeuf <sebastien.bo...@intel.com>
Date: Wed, 7 Aug 2019 07:15:32 -0700
Subject: [PATCH] libvhost-user: Fix the
VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD
 check

Vhost user protocol features are set as a bitmask. And the following
constant VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD value is 10 because the
bit
10 indicates if the features is set or not.

The proper way to check for the presence or absence of this feature is
to shift 1 by the value of this constant and then mask it with the
actual bitmask representing the supported protocol features.

This patch aims to fix the current code as it was not doing the
shifting, but instead it was masking directly with the value of the
constant itself.

Signed-off-by: Sebastien Boeuf <sebastien.bo...@intel.com>
---
 contrib/libvhost-user/libvhost-user.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-
user/libvhost-user.c
index fb61142bcc..11909fb7c1 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -1112,7 +1112,7 @@ bool vu_set_queue_host_notifier(VuDev *dev,
VuVirtq *vq, int fd,
 
     vmsg.fd_num = fd_num;
 
-    if ((dev->protocol_features & VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD)
== 0) {
+    if ((dev->protocol_features & (1ULL <<
VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD)) == 0) {
         return false;
     }
 
@@ -2537,7 +2537,7 @@ int64_t vu_fs_cache_request(VuDev *dev,
VhostUserSlaveRequest req, int fd,
 
     vmsg.fd_num = fd_num;
 
-    if ((dev->protocol_features & VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD)
== 0) {
+    if ((dev->protocol_features & (1ULL <<
VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD)) == 0) {
         return -EINVAL;
     }
 
-- 
2.17.1