Re: [tipc-discussion] [PATCH net 1/2] tipc: add tipc_bearer_min_mtu to calculate min mtu

[Tung Quang Nguyen via tipc-discussion]

>-----Original Message-----
>From: Xin Long <lucien....@gmail.com>
>Sent: Sunday, April 30, 2023 5:41 AM
>To: network dev <net...@vger.kernel.org>; tipc-discussion@lists.sourceforge.net
>Cc: k...@kernel.org; Eric Dumazet <eduma...@google.com>; Paolo Abeni 
><pab...@redhat.com>; da...@davemloft.net
>Subject: [tipc-discussion] [PATCH net 1/2] tipc: add tipc_bearer_min_mtu to 
>calculate min mtu
>
>As different media may requires different min mtu, and even the
>same media with different net family requires different min mtu,
>add tipc_bearer_min_mtu() to calculate min mtu accordingly.
>
>This API will be used to check the new mtu when doing the link
>mtu negotiation in the next patch.
>
>Signed-off-by: Xin Long <lucien....@gmail.com>
>---
> net/tipc/bearer.c    | 13 +++++++++++++
> net/tipc/bearer.h    |  3 +++
> net/tipc/udp_media.c |  5 +++--
> 3 files changed, 19 insertions(+), 2 deletions(-)
>
>diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
>index 35cac7733fd3..c5d2e8c45f88 100644
>--- a/net/tipc/bearer.c
>+++ b/net/tipc/bearer.c
>@@ -541,6 +541,19 @@ int tipc_bearer_mtu(struct net *net, u32 bearer_id)
>       return mtu;
> }
>
>+int tipc_bearer_min_mtu(struct net *net, u32 bearer_id)
>+{
>+      int mtu = TIPC_MIN_BEARER_MTU;
>+      struct tipc_bearer *b;
>+
>+      rcu_read_lock();
>+      b = rcu_dereference(tipc_net(net)->bearer_list[bearer_id]);
>+      if (b)
>+              mtu += b->encap_hlen;
>+      rcu_read_unlock();
>+      return mtu;
>+}
>+
> /* tipc_bearer_xmit_skb - sends buffer to destination over bearer
>  */
> void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id,
>diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h
>index 490ad6e5f7a3..bd0cc5c287ef 100644
>--- a/net/tipc/bearer.h
>+++ b/net/tipc/bearer.h
>@@ -146,6 +146,7 @@ struct tipc_media {
>  * @identity: array index of this bearer within TIPC bearer array
>  * @disc: ptr to link setup request
>  * @net_plane: network plane ('A' through 'H') currently associated with 
> bearer
>+ * @encap_hlen: encap headers length
>  * @up: bearer up flag (bit 0)
>  * @refcnt: tipc_bearer reference counter
>  *
>@@ -170,6 +171,7 @@ struct tipc_bearer {
>       u32 identity;
>       struct tipc_discoverer *disc;
>       char net_plane;
>+      u16 encap_hlen;
>       unsigned long up;
>       refcount_t refcnt;
> };
>@@ -232,6 +234,7 @@ int tipc_bearer_setup(void);
> void tipc_bearer_cleanup(void);
> void tipc_bearer_stop(struct net *net);
> int tipc_bearer_mtu(struct net *net, u32 bearer_id);
>+int tipc_bearer_min_mtu(struct net *net, u32 bearer_id);
> bool tipc_bearer_bcast_support(struct net *net, u32 bearer_id);
> void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id,
>                         struct sk_buff *skb,
>diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c
>index c2bb818704c8..0a85244fd618 100644
>--- a/net/tipc/udp_media.c
>+++ b/net/tipc/udp_media.c
>@@ -738,8 +738,8 @@ static int tipc_udp_enable(struct net *net, struct 
>tipc_bearer *b,
>                       udp_conf.local_ip.s_addr = local.ipv4.s_addr;
>               udp_conf.use_udp_checksums = false;
>               ub->ifindex = dev->ifindex;
>-              if (tipc_mtu_bad(dev, sizeof(struct iphdr) +
>-                                    sizeof(struct udphdr))) {
>+              b->encap_hlen = sizeof(struct iphdr) + sizeof(struct udphdr);
>+              if (tipc_mtu_bad(dev, b->encap_hlen)) {
>                       err = -EINVAL;
>                       goto err;
>               }
>@@ -760,6 +760,7 @@ static int tipc_udp_enable(struct net *net, struct 
>tipc_bearer *b,
>               else
>                       udp_conf.local_ip6 = local.ipv6;
>               ub->ifindex = dev->ifindex;
>+              b->encap_hlen = sizeof(struct ipv6hdr) + sizeof(struct udphdr);
tipc_mtu_bad() needs to be called here to check for the minimum required MTU 
like the way ipv4 UDP bearer does.
>               b->mtu = 1280;
> #endif
>       } else {
>--
>2.39.1
>
>
>
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