[PATCH 3/4] vhost: use alloca instead of vla sizeof

[Tyler Retzlaff <roretzla@linux.microsoft.com>]

RFC sample illustrating conversion of VLA to alloca() where
sizeof(array) was in use.

Signed-off-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
---
 lib/vhost/socket.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
index 96b3ab5..cedcfb2 100644
--- a/lib/vhost/socket.c
+++ b/lib/vhost/socket.c
@@ -110,7 +110,8 @@ struct vhost_user {
 {
 	struct iovec iov;
 	struct msghdr msgh;
-	char control[CMSG_SPACE(max_fds * sizeof(int))];
+	const size_t control_sz = sizeof(char) * CMSG_SPACE(max_fds * sizeof(int));
+	char *control = alloca(control_sz);
 	struct cmsghdr *cmsg;
 	int got_fds = 0;
 	int ret;
@@ -124,7 +125,7 @@ struct vhost_user {
 	msgh.msg_iov = &iov;
 	msgh.msg_iovlen = 1;
 	msgh.msg_control = control;
-	msgh.msg_controllen = sizeof(control);
+	msgh.msg_controllen = control_sz;
 
 	ret = recvmsg(sockfd, &msgh, 0);
 	if (ret <= 0) {
-- 
1.8.3.1