net: netfilter: move nf flowtable bpf initialization in nf_flow_table_module_init()

Move nf flowtable bpf initialization in nf_flow_table module load
routine since nf_flow_table_bpf is part of nf_flow_table module and not
nf_flow_table_inet one. This patch allows to avoid the following kernel
warning running the reproducer below:

$modprobe nf_flow_table_inet
$rmmod nf_flow_table_inet
$modprobe nf_flow_table_inet
modprobe: ERROR: could not insert 'nf_flow_table_inet': Invalid argument

[  184.081501] ------------[ cut here ]------------
[  184.081527] WARNING: CPU: 0 PID: 1362 at kernel/bpf/btf.c:8206 btf_populate_kfunc_set+0x23c/0x330
[  184.081550] CPU: 0 UID: 0 PID: 1362 Comm: modprobe Kdump: loaded Not tainted 6.11.0-0.rc5.22.el10.x86_64 #1
[  184.081553] Hardware name: Red Hat OpenStack Compute, BIOS 1.14.0-1.module+el8.4.0+8855+a9e237a9 04/01/2014
[  184.081554] RIP: 0010:btf_populate_kfunc_set+0x23c/0x330
[  184.081558] RSP: 0018:ff22cfb38071fc90 EFLAGS: 00010202
[  184.081559] RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000000
[  184.081560] RDX: 000000000000006e RSI: ffffffff95c00000 RDI: ff13805543436350
[  184.081561] RBP: ffffffffc0e22180 R08: ff13805543410808 R09: 000000000001ec00
[  184.081562] R10: ff13805541c8113c R11: 0000000000000010 R12: ff13805541b83c00
[  184.081563] R13: ff13805543410800 R14: 0000000000000001 R15: ffffffffc0e2259a
[  184.081564] FS:  00007fa436c46740(0000) GS:ff1380557ba00000(0000) knlGS:0000000000000000
[  184.081569] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  184.081570] CR2: 000055e7b3187000 CR3: 0000000100c48003 CR4: 0000000000771ef0
[  184.081571] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  184.081572] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  184.081572] PKRU: 55555554
[  184.081574] Call Trace:
[  184.081575]  <TASK>
[  184.081578]  ? show_trace_log_lvl+0x1b0/0x2f0
[  184.081580]  ? show_trace_log_lvl+0x1b0/0x2f0
[  184.081582]  ? __register_btf_kfunc_id_set+0x199/0x200
[  184.081585]  ? btf_populate_kfunc_set+0x23c/0x330
[  184.081586]  ? __warn.cold+0x93/0xed
[  184.081590]  ? btf_populate_kfunc_set+0x23c/0x330
[  184.081592]  ? report_bug+0xff/0x140
[  184.081594]  ? handle_bug+0x3a/0x70
[  184.081596]  ? exc_invalid_op+0x17/0x70
[  184.081597]  ? asm_exc_invalid_op+0x1a/0x20
[  184.081601]  ? btf_populate_kfunc_set+0x23c/0x330
[  184.081602]  __register_btf_kfunc_id_set+0x199/0x200
[  184.081605]  ? __pfx_nf_flow_inet_module_init+0x10/0x10 [nf_flow_table_inet]
[  184.081607]  do_one_initcall+0x58/0x300
[  184.081611]  do_init_module+0x60/0x230
[  184.081614]  __do_sys_init_module+0x17a/0x1b0
[  184.081617]  do_syscall_64+0x7d/0x160
[  184.081620]  ? __count_memcg_events+0x58/0xf0
[  184.081623]  ? handle_mm_fault+0x234/0x350
[  184.081626]  ? do_user_addr_fault+0x347/0x640
[  184.081630]  ? clear_bhb_loop+0x25/0x80
[  184.081633]  ? clear_bhb_loop+0x25/0x80
[  184.081634]  ? clear_bhb_loop+0x25/0x80
[  184.081637]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[  184.081639] RIP: 0033:0x7fa43652e4ce
[  184.081647] RSP: 002b:00007ffe8213be18 EFLAGS: 00000246 ORIG_RAX: 00000000000000af
[  184.081649] RAX: ffffffffffffffda RBX: 000055e7b3176c20 RCX: 00007fa43652e4ce
[  184.081650] RDX: 000055e7737fde79 RSI: 0000000000003990 RDI: 000055e7b3185380
[  184.081651] RBP: 000055e7737fde79 R08: 0000000000000007 R09: 000055e7b3179bd0
[  184.081651] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000040000
[  184.081652] R13: 000055e7b3176fa0 R14: 0000000000000000 R15: 000055e7b3179b80

Fixes: 391bb659 ("netfilter: Add bpf_xdp_flow_lookup kfunc")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Acked-by: Florian Westphal <fw@strlen.de>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Link: https://patch.msgid.link/20240911-nf-flowtable-bpf-modprob-fix-v1-1-f9fc075aafc3@kernel.orgSigned-off-by: Paolo Abeni <pabeni@redhat.com>

net/netfilter/nf_flow_table_core.c

@@ -670,8 +670,14 @@ static int __init nf_flow_table_module_init(void)
 	if (ret)
 		goto out_offload;
 
+	ret = nf_flow_register_bpf();
+	if (ret)
+		goto out_bpf;
+
 	return 0;
 
+out_bpf:
+	nf_flow_table_offload_exit();
 out_offload:
 	unregister_pernet_subsys(&nf_flow_table_net_ops);
 	return ret;

net/netfilter/nf_flow_table_inet.c

@@ -101,7 +101,7 @@ static int __init nf_flow_inet_module_init(void)
 	nft_register_flowtable_type(&flowtable_ipv6);
 	nft_register_flowtable_type(&flowtable_inet);
 
-	return nf_flow_register_bpf();
+	return 0;
 }
 
 static void __exit nf_flow_inet_module_exit(void)