When a chain is updated, a counter can be attached. if so,
the nft_counters_enabled should be increased.
test commands:
%nft add table ip filter
%nft add chain ip filter input { type filter hook input priority 4\; }
%iptables-compat -Z input
%nft delete chain ip filter input
we can see below messages.
[ 286.443720] jump label: negative count!
[ 286.448278] WARNING: CPU: 0 PID: 1459 at kernel/jump_label.c:197 __static_key_slow_dec_cpuslocked+0x6f/0xf0
[ 286.449144] Modules linked in: nf_tables nfnetlink ip_tables x_tables
[ 286.449144] CPU: 0 PID: 1459 Comm: nft Tainted: G W 4.17.0-rc2+ #12
[ 286.449144] RIP: 0010:__static_key_slow_dec_cpuslocked+0x6f/0xf0
[ 286.449144] RSP: 0018:ffff88010e5176f0 EFLAGS: 00010286
[ 286.449144] RAX: 000000000000001b RBX: ffffffffc0179500 RCX: ffffffffb8a82522
[ 286.449144] RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff88011b7e5eac
[ 286.449144] RBP: 0000000000000000 R08: ffffed00236fce5c R09: ffffed00236fce5b
[ 286.449144] R10: ffffffffc0179503 R11: ffffed00236fce5c R12: 0000000000000000
[ 286.449144] R13: ffff88011a28e448 R14: ffff88011a28e470 R15: dffffc0000000000
[ 286.449144] FS: 00007f0384328700(0000) GS:ffff88011b600000(0000) knlGS:0000000000000000
[ 286.449144] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 286.449144] CR2: 00007f038394bf10 CR3: 0000000104a86000 CR4: 00000000001006f0
[ 286.449144] Call Trace:
[ 286.449144] static_key_slow_dec+0x6a/0x70
[ 286.449144] nf_tables_chain_destroy+0x19d/0x210 [nf_tables]
[ 286.449144] nf_tables_commit+0x1891/0x1c50 [nf_tables]
[ 286.449144] nfnetlink_rcv+0x1148/0x13d0 [nfnetlink]
[ ... ]
Signed-off-by: Taehee Yoo <ap420073@xxxxxxxxx>
---
net/netfilter/nf_tables_api.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index e53e2e5..f730283 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1298,8 +1298,10 @@ static void nft_chain_stats_replace(struct nft_base_chain *chain,
rcu_assign_pointer(chain->stats, newstats);
synchronize_rcu();
free_percpu(oldstats);
- } else
+ } else {
rcu_assign_pointer(chain->stats, newstats);
+ static_branch_inc(&nft_counters_enabled);
+ }
}
static void nf_tables_chain_destroy(struct nft_ctx *ctx)
--
2.9.3
--
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