From: Christian Hopps <chopps@chopps.org>
To: devel@linux-ipsec.org
Cc: Steffen Klassert <steffen.klassert@secunet.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
netdev@vger.kernel.org, Christian Hopps <chopps@labn.net>,
Christian Hopps <chopps@chopps.org>
Subject: [PATCH ipsec-next] xfrm: add comments in the xfrm mtu calc function
Date: Fri, 15 Sep 2023 20:15:17 -0400 [thread overview]
Message-ID: <m2il8bq81d.fsf@chopps.org> (raw)
Document the [p]mtu values used by, and calculated for xfrms.
Signed-off-by: Christian Hopps <chopps@chopps.org>
---
net/xfrm/xfrm_policy.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 5c61ec04b839..2480717654b6 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3858,15 +3858,19 @@ static void xfrm_init_pmtu(struct xfrm_dst **bundle, int nr)
u32 pmtu, route_mtu_cached;
struct dst_entry *dst;
+ /* Get the xfrm's dst [p]mtu (i.e., the xfrm's intf/route). */
dst = &xdst->u.dst;
pmtu = dst_mtu(xfrm_dst_child(dst));
xdst->child_mtu_cached = pmtu;
+ /* Subtract the xfrm mode overhead. */
pmtu = xfrm_state_mtu(dst->xfrm, pmtu);
+ /* Get the inner traffic route's MTU. */
route_mtu_cached = dst_mtu(xdst->route);
xdst->route_mtu_cached = route_mtu_cached;
+ /* Update the xfrm's dst MTU to the minimum of these. */
if (pmtu > route_mtu_cached)
pmtu = route_mtu_cached;
--
2.41.0
reply other threads:[~2023-09-16 0:40 UTC|newest]
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