Tools: hv: use single send+recv buffer

send_buffer is used only once during registration. To reduce runtime
memory usage reuse the recv_buffer for registration. Also use
NLMSG_LENGTH instead of NLMSG_HDRLEN to take alignment into account.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 7 insertions, 11 deletions

diff --git a/tools/hv/hv_kvp_daemon.c b/tools/hv/hv_kvp_daemon.c
index 21bd7d4574fc..b8d6d541d854 100644
--- a/tools/hv/hv_kvp_daemon.c
+++ b/tools/hv/hv_kvp_daemon.c
@@ -1434,7 +1434,6 @@ int main(void)
         int     pool;
         char    *if_name;
         struct hv_kvp_ipaddr_value *kvp_ip_val;
-        char *kvp_send_buffer;
         char *kvp_recv_buffer;
         size_t kvp_recv_buffer_len;
 
@@ -1443,11 +1442,10 @@ int main(void)
         openlog("KVP", 0, LOG_USER);
         syslog(LOG_INFO, "KVP starting; pid is:%d", getpid());
 
-        kvp_recv_buffer_len = NLMSG_HDRLEN + sizeof(struct cn_msg) + sizeof(struct hv_kvp_msg);
-        kvp_send_buffer = calloc(1, kvp_recv_buffer_len);
+        kvp_recv_buffer_len = NLMSG_LENGTH(0) + sizeof(struct cn_msg) + sizeof(struct hv_kvp_msg);
         kvp_recv_buffer = calloc(1, kvp_recv_buffer_len);
-        if (!(kvp_send_buffer && kvp_recv_buffer)) {
-                syslog(LOG_ERR, "Failed to allocate netlink buffers");
+        if (!kvp_recv_buffer) {
+                syslog(LOG_ERR, "Failed to allocate netlink buffer");
                 exit(EXIT_FAILURE);
         }
         /*
@@ -1494,7 +1492,7 @@ int main(void)
         /*
          * Register ourselves with the kernel.
          */
-        message = (struct cn_msg *)kvp_send_buffer;
+        message = (struct cn_msg *)kvp_recv_buffer;
         message->id.idx = CN_KVP_IDX;
         message->id.val = CN_KVP_VAL;
 
diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c
index 8611962c672c..8bcb04096eb2 100644
--- a/tools/hv/hv_vss_daemon.c
+++ b/tools/hv/hv_vss_daemon.c
@@ -140,7 +140,6 @@ int main(void)
         struct cn_msg   *incoming_cn_msg;
         int     op;
         struct hv_vss_msg *vss_msg;
-        char *vss_send_buffer;
         char *vss_recv_buffer;
         size_t vss_recv_buffer_len;
 
@@ -150,10 +149,9 @@ int main(void)
         openlog("Hyper-V VSS", 0, LOG_USER);
         syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
 
-        vss_recv_buffer_len = NLMSG_HDRLEN + sizeof(struct cn_msg) + sizeof(struct hv_vss_msg);
-        vss_send_buffer = calloc(1, vss_recv_buffer_len);
+        vss_recv_buffer_len = NLMSG_LENGTH(0) + sizeof(struct cn_msg) + sizeof(struct hv_vss_msg);
         vss_recv_buffer = calloc(1, vss_recv_buffer_len);
-        if (!(vss_send_buffer && vss_recv_buffer)) {
+        if (!vss_recv_buffer) {
                 syslog(LOG_ERR, "Failed to allocate netlink buffers");
                 exit(EXIT_FAILURE);
         }
@@ -185,7 +183,7 @@ int main(void)
         /*
          * Register ourselves with the kernel.
          */
-        message = (struct cn_msg *)vss_send_buffer;
+        message = (struct cn_msg *)vss_recv_buffer;
         message->id.idx = CN_VSS_IDX;
         message->id.val = CN_VSS_VAL;
         message->ack = 0;