sit: convert configuration to RCU protection

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Now that SIT parameters are dynamically allocated, convert
tunnel->sit_parms to an RCU-protected pointer.

Updates in ipip6_tunnel_update() allocate a new parameter block,
publish it using rcu_assign_pointer(), and free the old one
via kfree_rcu().

We only need to unlink and re-link the tunnel in the hash table
if either saddr or daddr changed. When neither address changes,
the unhash/re-hash and synchronize_net() can be completely skipped.

Readers in ipip6_tunnel_lookup(), ipip6_tunnel_xmit(), ipip6_err(),
and ipip6_rcv() now safely dereference tunnel->sit_parms under RCU.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>
Link: https://patch.msgid.link/20260907075846.2913645-9-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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This commit is contained in:

Eric Dumazet 2026-09-07 07:58:45 +00:00 • committed by Jakub Kicinski

parent 3cd52b7c0b

commit 0301127e4d

2 changed files with 157 additions and 91 deletions

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3

include/net/ip_tunnels.h

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249

net/ipv6/sit.c

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