Re: [tipc-discussion] [PATCHv2 net 1/3] tipc: add tipc_bearer_min_mtu to calculate min mtu

[Xin L. <luc...@gm...>]

On Tue, May 2, 2023 at 11:37 PM Tung Quang Nguyen
<tun...@de...> wrote:
>
> >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.
> >
> >v1->v2:
> > - use bearer_get() to avoid the open code.
> This version change comment does not seem right. Please correct it to avoid confusion and put it after "---".
See the comment in Patch 2/3.

> >
> >Signed-off-by: Xin Long <luc...@gm...>
> >---
> > 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..0e9a29e1536b 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 = bearer_get(net, 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)) {
> I agree that calling tipc_mtu_bad() is not necessary for UDP bearer enabling. You can remove it in this patch.
To be honest, it's NOT appropriate to do code cleanup in this patch,
nor in net.git.

Thanks.

> >                       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);
> >               b->mtu = 1280;
> > #endif
> >       } else {
> >--
> >2.39.1
>