Improve MTU handling
- setting MTU on an interface updates the L3 max bytes too
- value cached in the adjacency is also updated
- MTU exceeded generates ICMP to sender
Change-Id: I343ec71d8e903b529594c4bd0543f04bc7f370b3
Signed-off-by: Neale Ranns <neale.ranns@cisco.com>
diff --git a/src/vnet/adj/adj.c b/src/vnet/adj/adj.c
index 5f7fe74..d28d519 100644
--- a/src/vnet/adj/adj.c
+++ b/src/vnet/adj/adj.c
@@ -338,6 +338,43 @@
adj_walk (sw_if_index, adj_feature_update_walk_cb, &ctx);
}
+static adj_walk_rc_t
+adj_mtu_update_walk_cb (adj_index_t ai,
+ void *arg)
+{
+ ip_adjacency_t *adj;
+
+ adj = adj_get(ai);
+
+ vnet_rewrite_update_mtu (vnet_get_main(),
+ &adj->rewrite_header);
+
+ return (ADJ_WALK_RC_CONTINUE);
+}
+
+static void
+adj_sw_mtu_update (vnet_main_t * vnm,
+ u32 sw_if_index,
+ void *ctx)
+{
+ /*
+ * Walk all the adjacencies on the interface to update the cached MTU
+ */
+ adj_walk (sw_if_index, adj_mtu_update_walk_cb, NULL);
+}
+
+void
+adj_mtu_update (u32 hw_if_index)
+{
+ /*
+ * Walk all the SW interfaces on the HW interface to update the cached MTU
+ */
+ vnet_hw_interface_walk_sw(vnet_get_main(),
+ hw_if_index,
+ adj_sw_mtu_update,
+ NULL);
+}
+
/**
* @brief Walk the Adjacencies on a given interface
*/
diff --git a/src/vnet/adj/adj.h b/src/vnet/adj/adj.h
index fe77d16..bcf6c04 100644
--- a/src/vnet/adj/adj.h
+++ b/src/vnet/adj/adj.h
@@ -345,6 +345,12 @@
extern void adj_feature_update (u32 sw_if_index, u8 arc_index, u8 is_enable);
/**
+ * @brief Notify the adjacency subsystem that the MTU settings for
+ * an HW interface have changed
+ */
+extern void adj_mtu_update (u32 hw_if_index);
+
+/**
* @brief
* The global adjacnecy pool. Exposed for fast/inline data-plane access
*/
diff --git a/src/vnet/adj/rewrite.c b/src/vnet/adj/rewrite.c
index 9150f2c..c21495a 100644
--- a/src/vnet/adj/rewrite.c
+++ b/src/vnet/adj/rewrite.c
@@ -77,15 +77,14 @@
vnet_sw_interface_t *si;
si = vnet_get_sw_interface_safe (vnm, rw->sw_if_index);
if (NULL != si)
- s = format (s, "%U: ", format_vnet_sw_interface_name, vnm, si);
+ s = format (s, "%U:", format_vnet_sw_interface_name, vnm, si);
else
s = format (s, "DELETED:%d", rw->sw_if_index);
}
/* Format rewrite string. */
if (rw->data_bytes > 0)
-
- s = format (s, "%U",
+ s = format (s, " %U",
format_hex_bytes,
rw->data + max_data_bytes - rw->data_bytes, rw->data_bytes);
@@ -111,6 +110,13 @@
}
void
+vnet_rewrite_update_mtu (vnet_main_t * vnm, vnet_rewrite_header_t * rw)
+{
+ rw->max_l3_packet_bytes =
+ vnet_sw_interface_get_mtu (vnm, rw->sw_if_index, VLIB_TX);
+}
+
+void
vnet_rewrite_for_sw_interface (vnet_main_t * vnm,
vnet_link_t link_type,
u32 sw_if_index,
diff --git a/src/vnet/adj/rewrite.h b/src/vnet/adj/rewrite.h
index 1dea72f..005ac41 100644
--- a/src/vnet/adj/rewrite.h
+++ b/src/vnet/adj/rewrite.h
@@ -328,6 +328,9 @@
u32 this_node,
u32 next_node, vnet_rewrite_header_t * rw);
+void vnet_rewrite_update_mtu (struct vnet_main_t *vnm,
+ vnet_rewrite_header_t * rw);
+
u8 *vnet_build_rewrite_for_sw_interface (struct vnet_main_t *vnm,
u32 sw_if_index,
vnet_link_t packet_type,
diff --git a/src/vnet/interface.c b/src/vnet/interface.c
index a34bb79..7516aec 100644
--- a/src/vnet/interface.c
+++ b/src/vnet/interface.c
@@ -122,6 +122,22 @@
/* helper_flags no redistribution */ 0);
}
+void
+vnet_hw_interface_set_mtu (vnet_main_t * vnm, u32 hw_if_index, u32 mtu)
+{
+ vnet_hw_interface_t *hi = vnet_get_hw_interface (vnm, hw_if_index);
+
+ if (hi->max_packet_bytes != mtu)
+ {
+ u16 l3_pad = hi->max_packet_bytes - hi->max_l3_packet_bytes[VLIB_TX];
+ hi->max_packet_bytes = mtu;
+ hi->max_l3_packet_bytes[VLIB_TX] =
+ hi->max_l3_packet_bytes[VLIB_RX] = mtu - l3_pad;
+ ethernet_set_flags (vnm, hw_if_index, ETHERNET_INTERFACE_FLAG_MTU);
+ adj_mtu_update (hw_if_index);
+ }
+}
+
static void
unserialize_vnet_hw_interface_set_flags (serialize_main_t * m, va_list * va)
{
diff --git a/src/vnet/interface_api.c b/src/vnet/interface_api.c
index 0541f31..ed116bc 100644
--- a/src/vnet/interface_api.c
+++ b/src/vnet/interface_api.c
@@ -98,7 +98,6 @@
{
vl_api_sw_interface_set_mtu_reply_t *rmp;
vnet_main_t *vnm = vnet_get_main ();
- u32 flags = ETHERNET_INTERFACE_FLAG_MTU;
u32 sw_if_index = ntohl (mp->sw_if_index);
u16 mtu = ntohs (mp->mtu);
ethernet_main_t *em = ðernet_main;
@@ -134,11 +133,7 @@
goto bad_sw_if_index;
}
- if (hi->max_packet_bytes != mtu)
- {
- hi->max_packet_bytes = mtu;
- ethernet_set_flags (vnm, si->hw_if_index, flags);
- }
+ vnet_hw_interface_set_mtu (vnm, si->hw_if_index, mtu);
BAD_SW_IF_INDEX_LABEL;
REPLY_MACRO (VL_API_SW_INTERFACE_SET_MTU_REPLY);
diff --git a/src/vnet/interface_cli.c b/src/vnet/interface_cli.c
index 5509e3f..8880d97 100644
--- a/src/vnet/interface_cli.c
+++ b/src/vnet/interface_cli.c
@@ -1132,7 +1132,6 @@
{
vnet_main_t *vnm = vnet_get_main ();
u32 hw_if_index, mtu;
- u32 flags = ETHERNET_INTERFACE_FLAG_MTU;
ethernet_main_t *em = ðernet_main;
if (unformat (input, "%d %U", &mtu,
@@ -1153,11 +1152,7 @@
return clib_error_return (0, "Invalid mtu (%d): must be <= (%d)", mtu,
hi->max_supported_packet_bytes);
- if (hi->max_packet_bytes != mtu)
- {
- hi->max_packet_bytes = mtu;
- ethernet_set_flags (vnm, hw_if_index, flags);
- }
+ vnet_hw_interface_set_mtu (vnm, hw_if_index, mtu);
}
else
return clib_error_return (0, "unknown input `%U'",
diff --git a/src/vnet/interface_funcs.h b/src/vnet/interface_funcs.h
index ac50e7c..5aecaff 100644
--- a/src/vnet/interface_funcs.h
+++ b/src/vnet/interface_funcs.h
@@ -292,6 +292,9 @@
vnet_hw_interface_rx_mode
mode);
+/* Set the MTU on the HW interface */
+void vnet_hw_interface_set_mtu (vnet_main_t * vnm, u32 hw_if_index, u32 mtu);
+
/* Formats sw/hw interface. */
format_function_t format_vnet_hw_interface;
format_function_t format_vnet_hw_interface_rx_mode;
diff --git a/src/vnet/ip/ip4_forward.c b/src/vnet/ip/ip4_forward.c
index ae45106..b9875d7 100644
--- a/src/vnet/ip/ip4_forward.c
+++ b/src/vnet/ip/ip4_forward.c
@@ -2109,16 +2109,26 @@
vnet_buffer (p1)->ip.save_rewrite_length = rw_len1;
/* Check MTU of outgoing interface. */
- error0 =
- (vlib_buffer_length_in_chain (vm, p0) >
- adj0[0].
- rewrite_header.max_l3_packet_bytes ? IP4_ERROR_MTU_EXCEEDED :
- error0);
- error1 =
- (vlib_buffer_length_in_chain (vm, p1) >
- adj1[0].
- rewrite_header.max_l3_packet_bytes ? IP4_ERROR_MTU_EXCEEDED :
- error1);
+ if (vlib_buffer_length_in_chain (vm, p0) >
+ adj0[0].rewrite_header.max_l3_packet_bytes)
+ {
+ error0 = IP4_ERROR_MTU_EXCEEDED;
+ next0 = IP4_REWRITE_NEXT_ICMP_ERROR;
+ icmp4_error_set_vnet_buffer
+ (p0, ICMP4_destination_unreachable,
+ ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
+ 0);
+ }
+ if (vlib_buffer_length_in_chain (vm, p1) >
+ adj1[0].rewrite_header.max_l3_packet_bytes)
+ {
+ error1 = IP4_ERROR_MTU_EXCEEDED;
+ next1 = IP4_REWRITE_NEXT_ICMP_ERROR;
+ icmp4_error_set_vnet_buffer
+ (p1, ICMP4_destination_unreachable,
+ ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
+ 0);
+ }
if (is_mcast)
{
@@ -2290,9 +2300,16 @@
vlib_buffer_length_in_chain (vm, p0) + rw_len0);
/* Check MTU of outgoing interface. */
- error0 = (vlib_buffer_length_in_chain (vm, p0)
- > adj0[0].rewrite_header.max_l3_packet_bytes
- ? IP4_ERROR_MTU_EXCEEDED : error0);
+ if (vlib_buffer_length_in_chain (vm, p0) >
+ adj0[0].rewrite_header.max_l3_packet_bytes)
+ {
+ error0 = IP4_ERROR_MTU_EXCEEDED;
+ next0 = IP4_REWRITE_NEXT_ICMP_ERROR;
+ icmp4_error_set_vnet_buffer
+ (p0, ICMP4_destination_unreachable,
+ ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
+ 0);
+ }
if (is_mcast)
{
error0 = ((adj0[0].rewrite_header.sw_if_index ==