diff mbox series

[4/7] batman-adv: Check hardif MTU against runtime MTU

Message ID 20230816164000.190884-5-sw@simonwunderlich.de (mailing list archive)
State Accepted
Commit 112cbcb4af90c4b108b120a28089872d2234a350
Delegated to: Netdev Maintainers
Headers show
Series [1/7] batman-adv: Start new development cycle | expand

Checks

Context Check Description
netdev/series_format warning Pull request is its own cover letter; Target tree name not specified in the subject
netdev/tree_selection success Guessed tree name to be net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1330 this patch: 1330
netdev/cc_maintainers warning 4 maintainers not CCed: edumazet@google.com a@unstable.cc mareklindner@neomailbox.ch pabeni@redhat.com
netdev/build_clang success Errors and warnings before: 1353 this patch: 1353
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1353 this patch: 1353
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 46 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Simon Wunderlich Aug. 16, 2023, 4:39 p.m. UTC 
From: Sven Eckelmann <sven@narfation.org>

If the MTU of the soft/mesh interface was already reduced (enough), it is
not necessary to print a warning about a hard interface not having a MTU to
transport ethernet payloads of 1500 bytes.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/hard-interface.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 41c1ad33d009..5a4ff9a81e74 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -9,6 +9,7 @@ 
 
 #include <linux/atomic.h>
 #include <linux/byteorder/generic.h>
+#include <linux/compiler.h>
 #include <linux/container_of.h>
 #include <linux/errno.h>
 #include <linux/gfp.h>
@@ -699,9 +700,14 @@  int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
 	struct batadv_priv *bat_priv;
 	__be16 ethertype = htons(ETH_P_BATMAN);
 	int max_header_len = batadv_max_header_len();
+	unsigned int required_mtu;
+	unsigned int hardif_mtu;
 	int ret;
 
-	if (hard_iface->net_dev->mtu < ETH_MIN_MTU + max_header_len)
+	hardif_mtu = READ_ONCE(hard_iface->net_dev->mtu);
+	required_mtu = READ_ONCE(soft_iface->mtu) + max_header_len;
+
+	if (hardif_mtu < ETH_MIN_MTU + max_header_len)
 		return -EINVAL;
 
 	if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
@@ -734,18 +740,18 @@  int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
 		    hard_iface->net_dev->name);
 
 	if (atomic_read(&bat_priv->fragmentation) &&
-	    hard_iface->net_dev->mtu < ETH_DATA_LEN + max_header_len)
+	    hardif_mtu < required_mtu)
 		batadv_info(hard_iface->soft_iface,
 			    "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to %i would solve the problem.\n",
-			    hard_iface->net_dev->name, hard_iface->net_dev->mtu,
-			    ETH_DATA_LEN + max_header_len);
+			    hard_iface->net_dev->name, hardif_mtu,
+			    required_mtu);
 
 	if (!atomic_read(&bat_priv->fragmentation) &&
-	    hard_iface->net_dev->mtu < ETH_DATA_LEN + max_header_len)
+	    hardif_mtu < required_mtu)
 		batadv_info(hard_iface->soft_iface,
 			    "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. If you experience problems getting traffic through try increasing the MTU to %i.\n",
-			    hard_iface->net_dev->name, hard_iface->net_dev->mtu,
-			    ETH_DATA_LEN + max_header_len);
+			    hard_iface->net_dev->name, hardif_mtu,
+			    required_mtu);
 
 	if (batadv_hardif_is_iface_up(hard_iface))
 		batadv_hardif_activate_interface(hard_iface);