Enable mux tracing

Summary: Enable mux tracing. If the kernel version is too old, turn it off due to instruction limits. Enable mux_trace_bpf_test.

Test Plan: Existing tests

Reviewers: #stirling, jps

Reviewed By: #stirling, jps

Subscribers: jps

Signed-off-by: Ryan Cheng <rcheng@pixielabs.ai>

Differential Revision: https://phab.corp.pixielabs.ai/D11652

GitOrigin-RevId: 604e9bf

src/stirling/source_connectors/socket_tracer/mux_trace_bpf_test.cc

@@ -35,6 +35,7 @@
 #include "src/stirling/source_connectors/socket_tracer/testing/container_images.h"
 #include "src/stirling/source_connectors/socket_tracer/testing/socket_trace_bpf_test_fixture.h"
 #include "src/stirling/testing/common.h"
+#include "src/stirling/utils/linux_headers.h"
 
 namespace px {
 namespace stirling {
@@ -147,9 +148,16 @@ inline auto EqMuxRecord(const mux::Record& x) {
 // Test Scenarios
 //-----------------------------------------------------------------------------
 
-TEST_F(MuxTraceTest, DISABLED_Capture) {
-  // Uncomment to enable tracing
-  // FLAGS_stirling_conn_trace_pid = server_.process_pid();
+TEST_F(MuxTraceTest, Capture) {
+  // If kernel version is older than 5.2, we turn off some protocol tracers due to instruction
+  // limits.
+  constexpr uint32_t kLinux5p2VersionCode = 328192;
+  auto kernel_version = utils::GetKernelVersion();
+  if (!kernel_version.ok() || kernel_version.ConsumeValueOrDie().code() < kLinux5p2VersionCode) {
+    VLOG(1) << "Mux Tracing is turned off for kernel version older than 5.2.";
+    return;
+  }
+
   StartTransferDataThread();
 
   ASSERT_OK(RunThriftMuxClient());

src/stirling/source_connectors/socket_tracer/socket_trace_connector.cc

@@ -44,6 +44,7 @@
 #include "src/stirling/source_connectors/socket_tracer/proto/sock_event.pb.h"
 #include "src/stirling/source_connectors/socket_tracer/protocols/http/utils.h"
 #include "src/stirling/source_connectors/socket_tracer/protocols/http2/grpc.h"
+#include "src/stirling/utils/linux_headers.h"
 #include "src/stirling/utils/proc_path_tools.h"
 
 // 50 X less often than the normal sampling frequency. Based on the conn_stats_table.h's
@@ -89,8 +90,7 @@ DEFINE_bool(stirling_enable_nats_tracing, true,
             "If true, stirling will trace and process NATS messages.");
 DEFINE_bool(stirling_enable_kafka_tracing, true,
             "If true, stirling will trace and process Kafka messages.");
-DEFINE_bool(stirling_enable_mux_tracing,
-            gflags::BoolFromEnv("PL_STIRLING_TRACER_ENABLE_MUX", false),
+DEFINE_bool(stirling_enable_mux_tracing, gflags::BoolFromEnv("PL_STIRLING_TRACER_ENABLE_MUX", true),
             "If true, stirling will trace and process Mux messages.");
 
 DEFINE_bool(stirling_disable_self_tracing, true,
@@ -163,6 +163,15 @@ void SocketTraceConnector::InitProtocolTransferSpecs() {
 #define TRANSFER_STREAM_PROTOCOL(protocol_name) \
   &SocketTraceConnector::TransferStream<protocols::protocol_name::ProtocolTraits>
 
+  // If kernel version is older than 5.2, we turn off some protocol tracers due to instruction
+  // limits.
+  constexpr uint32_t kLinux5p2VersionCode = 328192;
+  auto kernel_version = utils::GetKernelVersion();
+  if (!kernel_version.ok() || kernel_version.ConsumeValueOrDie().code() < kLinux5p2VersionCode) {
+    VLOG(1) << "Turning off mux protocol tracer due to eBPF instruction limit.";
+    FLAGS_stirling_enable_mux_tracing = false;
+  }
+
   // PROTOCOL_LIST: Requires update on new protocols.
 
   // We popluate transfer_specs_by_protocol so that we guarantee the protocol_transfer_specs_