device: only ready existing ethtool ring settings if needed

Imagine you have a veth device. That device supports certain offload features
(like "ethtool.feature-rx-checksum") but doesn't support any ring
options. Even trying to read the current ring settings will fail.

If you try to activate that profile, NMDevice previously would always
try to fetch the ring options and log a warning and extra debugging
messages:

  <trace> [1590511552.3943] ethtool[31]: ETHTOOL_GRINGPARAM, v: failed: Operation not supported
  <trace> [1590511552.3944] ethtool[31]: get-ring: failure getting ring settings
  <warn>  [1590511552.3944] device (v): ethtool: failure getting ring settings (cannot read)

It does so, although you didn't specify any ring settings and there
was no need to fetch the ring settings to begin with.

Avoid this extra logging by only fetching the ring option when they
are actually required.

1 files changed, 35 insertions, 55 deletions

diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index 9b018ccc8c..aae1949887 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -950,50 +950,6 @@ _ethtool_coalesce_set (NMDevice *self,
 	_LOGD (LOGD_DEVICE, "ethtool: coalesce settings successfully set");
 }
 
-static gboolean
-_ethtool_init_ring (NMDevice *self,
-                    NMPlatform *platform,
-                    NMSettingEthtool *s_ethtool,
-                    NMEthtoolRingState *ring)
-{
-	GHashTable *hash;
-	GHashTableIter iter;
-	const char *name;
-	GVariant *variant;
-	gsize n_ring_set = 0;
-
-	nm_assert (self);
-	nm_assert (platform);
-	nm_assert (ring);
-	nm_assert (NM_IS_SETTING_ETHTOOL (s_ethtool));
-
-	hash = _nm_setting_option_hash (NM_SETTING (s_ethtool), FALSE);
-	if (!hash)
-		return FALSE;
-
-	g_hash_table_iter_init (&iter, hash);
-	while (g_hash_table_iter_next (&iter, (gpointer *) &name, (gpointer *) &variant)) {
-		if (!g_variant_is_of_type (variant, G_VARIANT_TYPE_UINT32))
-			continue;
-		if (!nm_ethtool_optname_is_ring (name))
-			continue;
-
-		if (!nm_platform_ethtool_init_ring (platform,
-		                                    ring,
-		                                    name,
-		                                    g_variant_get_uint32(variant))) {
-			_LOGW (LOGD_DEVICE, "ethtool: invalid ring setting %s", name);
-		    return FALSE;
-		}
-		++n_ring_set;
-
-	}
-
-	return !!n_ring_set;
-}
-
-
-
 static void
 _ethtool_ring_reset (NMDevice *self,
                      NMPlatform *platform,
@@ -1025,25 +981,49 @@ _ethtool_ring_set (NMDevice *self,
 {
 	NMEthtoolRingState ring_old;
 	NMEthtoolRingState ring_new;
+	GHashTable *hash;
+	GHashTableIter iter;
+	const char *name;
+	GVariant *variant;
+	gboolean has_old = FALSE;
 
-	nm_assert (ethtool_state);
 	nm_assert (NM_IS_DEVICE (self));
 	nm_assert (NM_IS_PLATFORM (platform));
 	nm_assert (NM_IS_SETTING_ETHTOOL (s_ethtool));
+	nm_assert (ethtool_state);
+	nm_assert (!ethtool_state->ring);
 
-	if (!nm_platform_ethtool_get_link_ring (platform,
-	                                        ethtool_state->ifindex,
-	                                        &ring_old)) {
-		_LOGW (LOGD_DEVICE, "ethtool: failure getting ring settings (cannot read)");
+	hash = _nm_setting_option_hash (NM_SETTING (s_ethtool), FALSE);
+	if (!hash)
 		return;
-	}
 
-	ring_new = ring_old;
+	g_hash_table_iter_init (&iter, hash);
+	while (g_hash_table_iter_next (&iter, (gpointer *) &name, (gpointer *) &variant)) {
+		if (!nm_ethtool_optname_is_ring (name))
+			continue;
+		nm_assert (g_variant_is_of_type (variant, G_VARIANT_TYPE_UINT32));
+
+		if (!has_old) {
+			if (!nm_platform_ethtool_get_link_ring (platform,
+			                                        ethtool_state->ifindex,
+			                                        &ring_old)) {
+				_LOGW (LOGD_DEVICE, "ethtool: failure setting ring options (cannot read existing setting)");
+				return;
+			}
+			has_old = TRUE;
+			ring_new = ring_old;
+		}
 
-	if (!_ethtool_init_ring (self,
-	                         platform,
-	                         s_ethtool,
-	                         &ring_new))
+		if (!nm_platform_ethtool_init_ring (platform,
+		                                    &ring_new,
+		                                    name,
+		                                    g_variant_get_uint32 (variant))) {
+			_LOGW (LOGD_DEVICE, "ethtool: invalid ring setting %s", name);
+			return;
+		}
+	}
+
+	if (!has_old)
 		return;
 
 	ethtool_state->ring = nm_memdup (&ring_old, sizeof (ring_old));