[Qemu-devel] [PATCH 3/3] trace: enable tracing in qemu-nbd

["Denis V. Lunev" <den@openvz.org>]

Pls note, trace_init_backends() must be called in the final process, i.e.
after daemonization. This is necessary to keep tracing thread in the
proper process.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
---
 qemu-nbd.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/qemu-nbd.c b/qemu-nbd.c
index 3e54113..8e59098 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -26,12 +26,14 @@
 #include "qemu/main-loop.h"
 #include "qemu/error-report.h"
 #include "qemu/config-file.h"
+#include "qemu/log.h"
 #include "block/snapshot.h"
 #include "qapi/util.h"
 #include "qapi/qmp/qstring.h"
 #include "qom/object_interfaces.h"
 #include "io/channel-socket.h"
 #include "crypto/init.h"
+#include "trace/control.h"
 
 #include <getopt.h>
 #include <libgen.h>
@@ -87,6 +89,7 @@ static void usage(const char *name)
 "General purpose options:\n"
 "  --object type,id=ID,...   define an object such as 'secret' for providing\n"
 "                            passwords and/or encryption keys\n"
+"  -T, --trace FILE          enable trace events listed in the given file\n"
 #ifdef __linux__
 "Kernel NBD client support:\n"
 "  -c, --connect=DEV         connect FILE to the local NBD device DEV\n"
@@ -497,6 +500,7 @@ int main(int argc, char **argv)
         { "export-name", required_argument, NULL, 'x' },
         { "tls-creds", required_argument, NULL, QEMU_NBD_OPT_TLSCREDS },
         { "image-opts", no_argument, NULL, QEMU_NBD_OPT_IMAGE_OPTS },
+        { "trace", required_argument, NULL, 'T' },
         { NULL, 0, NULL, 0 }
     };
     int ch;
@@ -517,6 +521,7 @@ int main(int argc, char **argv)
     const char *tlscredsid = NULL;
     bool imageOpts = false;
     bool writethrough = true;
+    char *trace_file = NULL;
 
     /* The client thread uses SIGTERM to interrupt the server.  A signal
      * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
@@ -533,6 +538,7 @@ int main(int argc, char **argv)
 
     module_call_init(MODULE_INIT_QOM);
     qemu_add_opts(&qemu_object_opts);
+    qemu_add_opts(&qemu_trace_opts);
     qemu_init_exec_dir(argv[0]);
 
     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
@@ -705,6 +711,9 @@ int main(int argc, char **argv)
         case QEMU_NBD_OPT_IMAGE_OPTS:
             imageOpts = true;
             break;
+        case 'T':
+            trace_file = trace_opt_parse(optarg, trace_file);
+            break;
         }
     }
 
@@ -720,6 +729,12 @@ int main(int argc, char **argv)
         exit(EXIT_FAILURE);
     }
 
+    if (!trace_init_backends()) {
+        exit(1);
+    }
+    trace_init_file(trace_file);
+    qemu_set_log(LOG_TRACE);
+
     if (tlscredsid) {
         if (sockpath) {
             error_report("TLS is only supported with IPv4/IPv6");
-- 
2.1.4