netdev-dpdk: Fix memory leak when configuring rx-steering.

VLOG_WARN_BUF() allocates a new string with xasprintf() every time it is
called and overwrites *errp without freeing the previous value. This can
lead to a memory leak if multiple warnings are emitted or if a later
hard error in netdev_dpdk_set_config() also writes to errp.

The three cases in dpdk_set_rx_steer_config() are not fatal errors:
- unsupported rx-steering value
- rss+lacp on non-ethernet port
- rss+lacp together with hw-offload

In all cases program simply log a warning and fall back to default RSS
steering. Configuration continues normally (err remains 0 and execution
flow do not goto out).

Therefore change them to plain VLOG_WARN(). As a result the 'errp'
parameter becomes unused and is removed from the function signature and
the call site in netdev_dpdk_set_config().

This makes the code cleaner and consistent with the rest of netdev-dpdk.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: fc06ea9 ("netdev-dpdk: Add custom rx-steering configuration.")
Signed-off-by: Mikhail Dmitrichenko <m.dmitrichenko222@gmail.com>
Signed-off-by: Kevin Traynor <ktraynor@redhat.com>

Author: Mikhail Dmitrichenko

lib/netdev-dpdk.c

@@ -2270,30 +2270,28 @@ dpdk_process_queue_size(struct netdev *netdev, const struct smap *args,
 
 static void
 dpdk_set_rx_steer_config(struct netdev *netdev, struct netdev_dpdk *dev,
-                         const struct smap *args, char **errp)
+                         const struct smap *args)
 {
     const char *arg = smap_get_def(args, "rx-steering", "rss");
     uint64_t flags = 0;
 
     if (!strcmp(arg, "rss+lacp")) {
         flags = DPDK_RX_STEER_LACP;
     } else if (strcmp(arg, "rss")) {
-        VLOG_WARN_BUF(errp, "%s: options:rx-steering "
-                      "unsupported parameter value '%s'",
-                      netdev_get_name(netdev), arg);
+        VLOG_WARN("%s: options:rx-steering unsupported parameter value '%s'",
+                  netdev_get_name(netdev), arg);
     }
 
     if (flags && dev->type != DPDK_DEV_ETH) {
-        VLOG_WARN_BUF(errp, "%s: options:rx-steering "
-                      "is only supported on ethernet ports",
-                      netdev_get_name(netdev));
+        VLOG_WARN("%s: options:rx-steering "
+                  "is only supported on ethernet ports",
+                  netdev_get_name(netdev));
         flags = 0;
     }
 
     if (flags && netdev_is_flow_api_enabled()) {
-        VLOG_WARN_BUF(errp, "%s: options:rx-steering "
-                      "is incompatible with hw-offload",
-                      netdev_get_name(netdev));
+        VLOG_WARN("%s: options:rx-steering is incompatible with hw-offload",
+                  netdev_get_name(netdev));
         flags = 0;
     }
 
@@ -2323,7 +2321,7 @@ netdev_dpdk_set_config(struct netdev *netdev, const struct smap *args,
     ovs_mutex_lock(&dpdk_mutex);
     ovs_mutex_lock(&dev->mutex);
 
-    dpdk_set_rx_steer_config(netdev, dev, args, errp);
+    dpdk_set_rx_steer_config(netdev, dev, args);
 
     dpdk_set_rxq_config(dev, args);