Re: [bpf-next PATCH v2 5/5] selftest/bpf: Use global variables instead of maps for test_tcpbpf_kern
From: Martin KaFai Lau <hidden>
Date: 2020-11-03 01:26:30
Also in:
bpf
On Sat, Oct 31, 2020 at 11:52:37AM -0700, Alexander Duyck wrote: [ ... ]
quoted hunk ↗ jump to hunk
+struct tcpbpf_globals global = { 0 }; int _version SEC("version") = 1; SEC("sockops")@@ -105,29 +72,15 @@ int bpf_testcb(struct bpf_sock_ops *skops) op = (int) skops->op; - update_event_map(op); + global.event_map |= (1 << op); switch (op) { case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: /* Test failure to set largest cb flag (assumes not defined) */ - bad_call_rv = bpf_sock_ops_cb_flags_set(skops, 0x80); + global.bad_cb_test_rv = bpf_sock_ops_cb_flags_set(skops, 0x80); /* Set callback */ - good_call_rv = bpf_sock_ops_cb_flags_set(skops, + global.good_cb_test_rv = bpf_sock_ops_cb_flags_set(skops, BPF_SOCK_OPS_STATE_CB_FLAG); - /* Update results */ - { - __u32 key = 0; - struct tcpbpf_globals g, *gp; - - gp = bpf_map_lookup_elem(&global_map, &key); - if (!gp) - break; - g = *gp; - g.bad_cb_test_rv = bad_call_rv; - g.good_cb_test_rv = good_call_rv; - bpf_map_update_elem(&global_map, &key, &g, - BPF_ANY); - } break; case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: skops->sk_txhash = 0x12345f;@@ -143,10 +96,8 @@ int bpf_testcb(struct bpf_sock_ops *skops) thdr = (struct tcphdr *)(header + offset); v = thdr->syn; - __u32 key = 1; - bpf_map_update_elem(&sockopt_results, &key, &v, - BPF_ANY); + global.tcp_saved_syn = v; } } break;@@ -156,25 +107,16 @@ int bpf_testcb(struct bpf_sock_ops *skops) break; case BPF_SOCK_OPS_STATE_CB: if (skops->args[1] == BPF_TCP_CLOSE) { - __u32 key = 0; - struct tcpbpf_globals g, *gp; - - gp = bpf_map_lookup_elem(&global_map, &key); - if (!gp) - break; - g = *gp; if (skops->args[0] == BPF_TCP_LISTEN) { - g.num_listen++; + global.num_listen++; } else { - g.total_retrans = skops->total_retrans; - g.data_segs_in = skops->data_segs_in; - g.data_segs_out = skops->data_segs_out; - g.bytes_received = skops->bytes_received; - g.bytes_acked = skops->bytes_acked; + global.total_retrans = skops->total_retrans; + global.data_segs_in = skops->data_segs_in; + global.data_segs_out = skops->data_segs_out; + global.bytes_received = skops->bytes_received; + global.bytes_acked = skops->bytes_acked; } - g.num_close_events++; - bpf_map_update_elem(&global_map, &key, &g, - BPF_ANY);
It is interesting that there is no race in the original "g.num_close_events++" followed by the bpf_map_update_elem(). It seems quite fragile though.
+ global.num_close_events++;
There is __sync_fetch_and_add(). not sure about the global.event_map though, may be use an individual variable for each _CB. Thoughts?
quoted hunk ↗ jump to hunk
} break; case BPF_SOCK_OPS_TCP_LISTEN_CB:@@ -182,9 +124,7 @@ int bpf_testcb(struct bpf_sock_ops *skops) v = bpf_setsockopt(skops, IPPROTO_TCP, TCP_SAVE_SYN, &save_syn, sizeof(save_syn)); /* Update global map w/ result of setsock opt */ - __u32 key = 0; - - bpf_map_update_elem(&sockopt_results, &key, &v, BPF_ANY); + global.tcp_save_syn = v; break; default: rv = -1;diff --git a/tools/testing/selftests/bpf/test_tcpbpf.h b/tools/testing/selftests/bpf/test_tcpbpf.h index 6220b95cbd02..0ed33521cbbb 100644 --- a/tools/testing/selftests/bpf/test_tcpbpf.h +++ b/tools/testing/selftests/bpf/test_tcpbpf.h@@ -14,5 +14,7 @@ struct tcpbpf_globals { __u64 bytes_acked; __u32 num_listen; __u32 num_close_events; + __u32 tcp_save_syn; + __u32 tcp_saved_syn; }; #endif