net/colo: Match is-enabled probe to tracepoint

Build of QEMU with dtrace fails on macOS:

  LINK    x86_64-softmmu/qemu-system-x86_64
error: probe colo_compare_miscompare doesn't exist
error: Could not register probes
ld: error creating dtrace DOF section for architecture x86_64

The reason of the error is explained by Adam Leventhal [1]:

  Note that is-enabled probes don't have the stability magic so I'm not
  sure how things would work if only is-enabled probes were used.

net/colo code uses is-enabled probes to determine if other probes should
be used but colo_compare_miscompare itself is not used explicitly.
Linker doesn't include the symbol and build fails.

The issue can be resolved if is-enabled probe matches the actual trace
point that is used inside the test. Packet dump toggle is replaced with
a compile-time conditional definition.

1. http://markmail.org/message/6grq2ygr5nwdwsnb

Fixes: f4b618360e ("colo-compare: add TCP, UDP, ICMP packet comparison")
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Cameron Esfahani <dirty@apple.com>
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Zhang Chen <chen.zhang@intel.com>
Message-id: 20200717093517.73397-5-r.bolshakov@yadro.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

3 files changed, 30 insertions, 24 deletions

diff --git a/net/colo-compare.c b/net/colo-compare.c
index 2c20de1537..0b3215dee0 100644
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -54,6 +54,8 @@ static NotifierList colo_compare_notifiers =
 #define REGULAR_PACKET_CHECK_MS 3000
 #define DEFAULT_TIME_OUT_MS 3000
 
+/* #define DEBUG_COLO_PACKETS */
+
 static QemuMutex colo_compare_mutex;
 static bool colo_compare_active;
 static QemuMutex event_mtx;
@@ -328,7 +330,7 @@ static int colo_compare_packet_payload(Packet *ppkt,
                                        uint16_t len)
 
 {
-    if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) {
+    if (trace_event_get_state_backends(TRACE_COLO_COMPARE_IP_INFO)) {
         char pri_ip_src[20], pri_ip_dst[20], sec_ip_src[20], sec_ip_dst[20];
 
         strcpy(pri_ip_src, inet_ntoa(ppkt->ip->ip_src));
@@ -493,12 +495,12 @@ sec:
         g_queue_push_head(&conn->primary_list, ppkt);
         g_queue_push_head(&conn->secondary_list, spkt);
 
-        if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) {
-            qemu_hexdump((char *)ppkt->data, stderr,
-                        "colo-compare ppkt", ppkt->size);
-            qemu_hexdump((char *)spkt->data, stderr,
-                        "colo-compare spkt", spkt->size);
-        }
+#ifdef DEBUG_COLO_PACKETS
+        qemu_hexdump((char *)ppkt->data, stderr,
+                     "colo-compare ppkt", ppkt->size);
+        qemu_hexdump((char *)spkt->data, stderr,
+                     "colo-compare spkt", spkt->size);
+#endif
 
         colo_compare_inconsistency_notify(s);
     }
@@ -534,12 +536,12 @@ static int colo_packet_compare_udp(Packet *spkt, Packet *ppkt)
                                     ppkt->size - offset)) {
         trace_colo_compare_udp_miscompare("primary pkt size", ppkt->size);
         trace_colo_compare_udp_miscompare("Secondary pkt size", spkt->size);
-        if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) {
-            qemu_hexdump((char *)ppkt->data, stderr, "colo-compare pri pkt",
-                         ppkt->size);
-            qemu_hexdump((char *)spkt->data, stderr, "colo-compare sec pkt",
-                         spkt->size);
-        }
+#ifdef DEBUG_COLO_PACKETS
+        qemu_hexdump((char *)ppkt->data, stderr, "colo-compare pri pkt",
+                     ppkt->size);
+        qemu_hexdump((char *)spkt->data, stderr, "colo-compare sec pkt",
+                     spkt->size);
+#endif
         return -1;
     } else {
         return 0;
@@ -577,12 +579,12 @@ static int colo_packet_compare_icmp(Packet *spkt, Packet *ppkt)
                                            ppkt->size);
         trace_colo_compare_icmp_miscompare("Secondary pkt size",
                                            spkt->size);
-        if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) {
-            qemu_hexdump((char *)ppkt->data, stderr, "colo-compare pri pkt",
-                         ppkt->size);
-            qemu_hexdump((char *)spkt->data, stderr, "colo-compare sec pkt",
-                         spkt->size);
-        }
+#ifdef DEBUG_COLO_PACKETS
+        qemu_hexdump((char *)ppkt->data, stderr, "colo-compare pri pkt",
+                     ppkt->size);
+        qemu_hexdump((char *)spkt->data, stderr, "colo-compare sec pkt",
+                     spkt->size);
+#endif
         return -1;
     } else {
         return 0;
@@ -598,7 +600,7 @@ static int colo_packet_compare_other(Packet *spkt, Packet *ppkt)
     uint16_t offset = ppkt->vnet_hdr_len;
 
     trace_colo_compare_main("compare other");
-    if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) {
+    if (trace_event_get_state_backends(TRACE_COLO_COMPARE_IP_INFO)) {
         char pri_ip_src[20], pri_ip_dst[20], sec_ip_src[20], sec_ip_dst[20];
 
         strcpy(pri_ip_src, inet_ntoa(ppkt->ip->ip_src));
diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c
index 1aaad101b6..576b019d09 100644
--- a/net/filter-rewriter.c
+++ b/net/filter-rewriter.c
@@ -76,11 +76,14 @@ static int handle_primary_tcp_pkt(RewriterState *rf,
     struct tcp_hdr *tcp_pkt;
 
     tcp_pkt = (struct tcp_hdr *)pkt->transport_header;
-    if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_DEBUG)) {
+    if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_PKT_INFO)) {
         trace_colo_filter_rewriter_pkt_info(__func__,
                     inet_ntoa(pkt->ip->ip_src), inet_ntoa(pkt->ip->ip_dst),
                     ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack),
                     tcp_pkt->th_flags);
+    }
+    if (trace_event_get_state_backends(
+          TRACE_COLO_FILTER_REWRITER_CONN_OFFSET)) {
         trace_colo_filter_rewriter_conn_offset(conn->offset);
     }
 
@@ -180,11 +183,14 @@ static int handle_secondary_tcp_pkt(RewriterState *rf,
 
     tcp_pkt = (struct tcp_hdr *)pkt->transport_header;
 
-    if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_DEBUG)) {
+    if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_PKT_INFO)) {
         trace_colo_filter_rewriter_pkt_info(__func__,
                     inet_ntoa(pkt->ip->ip_src), inet_ntoa(pkt->ip->ip_dst),
                     ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack),
                     tcp_pkt->th_flags);
+    }
+    if (trace_event_get_state_backends(
+          TRACE_COLO_FILTER_REWRITER_CONN_OFFSET)) {
         trace_colo_filter_rewriter_conn_offset(conn->offset);
     }
 
diff --git a/net/trace-events b/net/trace-events
index fa49c71533..bfaff7891d 100644
--- a/net/trace-events
+++ b/net/trace-events
@@ -17,10 +17,8 @@ colo_compare_udp_miscompare(const char *sta, int size) ": %s = %d"
 colo_compare_icmp_miscompare(const char *sta, int size) ": %s = %d"
 colo_compare_ip_info(int psize, const char *sta, const char *stb, int ssize, const char *stc, const char *std) "ppkt size = %d, ip_src = %s, ip_dst = %s, spkt size = %d, ip_src = %s, ip_dst = %s"
 colo_old_packet_check_found(int64_t old_time) "%" PRId64
-colo_compare_miscompare(void) ""
 colo_compare_tcp_info(const char *pkt, uint32_t seq, uint32_t ack, int hdlen, int pdlen, int offset, int flags) "%s: seq/ack= %u/%u hdlen= %d pdlen= %d offset= %d flags=%d"
 
 # filter-rewriter.c
-colo_filter_rewriter_debug(void) ""
 colo_filter_rewriter_pkt_info(const char *func, const char *src, const char *dst, uint32_t seq, uint32_t ack, uint32_t flag) "%s: src/dst: %s/%s p: seq/ack=%u/%u  flags=0x%x"
 colo_filter_rewriter_conn_offset(uint32_t offset) ": offset=%u"