From 02a176d42a88805b3520148a4eee28b0760cd8c0 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 18 Jun 2024 12:39:14 -0700 Subject: [PATCH] ipv6: bring NLM_DONE out to a separate recv() again MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit under Fixes optimized the number of recv() calls needed during RTM_GETROUTE dumps, but we got multiple reports of applications hanging on recv() calls. Applications expect that a route dump will be terminated with a recv() reading an individual NLM_DONE message. Coalescing NLM_DONE is perfectly legal in netlink, but even tho reporters fixed the code in respective projects, chances are it will take time for those applications to get updated. So revert to old behavior (for now)? This is an IPv6 version of commit 460b0d33cf10 ("inet: bring NLM_DONE out to a separate recv() again"). Reported-by: Maciej Żenczykowski Link: https://lore.kernel.org/all/CANP3RGc1RG71oPEBXNx_WZFP9AyphJefdO4paczN92n__ds4ow@mail.gmail.com Reported-by: Stefano Brivio Link: https://lore.kernel.org/all/20240315124808.033ff58d@elisabeth Reported-by: Ilya Maximets Link: https://lore.kernel.org/all/02b50aae-f0e9-47a4-8365-a977a85975d3@ovn.org Fixes: 5fc68320c1fb ("ipv6: remove RTNL protection from inet6_dump_fib()") Tested-by: Ilya Maximets Link: https://lore.kernel.org/r/20240618193914.561782-1-kuba@kernel.org Signed-off-by: Jakub Kicinski --- net/ipv6/ip6_fib.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 6e57c03e3255..83e4f9855ae1 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -2514,7 +2514,8 @@ int __init fib6_init(void) goto out_kmem_cache_create; ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETROUTE, NULL, - inet6_dump_fib, RTNL_FLAG_DUMP_UNLOCKED); + inet6_dump_fib, RTNL_FLAG_DUMP_UNLOCKED | + RTNL_FLAG_DUMP_SPLIT_NLM_DONE); if (ret) goto out_unregister_subsys;