[Qemu-devel] [PATCH v3 0/5] trace: enable tracing in qemu-io/qemu-nbd/qemu-img

[Qemu-devel] [PATCH v3 0/5] trace: enable tracing in qemu-io/qemu-nbd/qemu-img

[Denis V. Lunev]

Changes from v2:
- tweaked man-pages of qemu-nbd/qemu-img
- added support for qemu-img (patches 4-5 as suggested)

Changes from v1:
- fixed nits found by Eric

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>

Denis V. Lunev (5):
  trace: move qemu_trace_opts to trace/control.c
  trace: enable tracing in qemu-io
  trace: enable tracing in qemu-nbd
  qemu-img: move common options parsing before commands processing
  trace: enable tracing in qemu-img

 qemu-img.c      | 51 ++++++++++++++++++++++++++++++++++++++-------------
 qemu-img.texi   | 34 +++++++++++++++++++++++++++++++++-
 qemu-io.c       | 17 +++++++++++++----
 qemu-nbd.c      | 18 +++++++++++++++++-
 qemu-nbd.texi   | 28 ++++++++++++++++++++++++++++
 trace/control.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
 trace/control.h | 24 +++++++++++++-----------
 vl.c            | 37 +------------------------------------
 8 files changed, 186 insertions(+), 67 deletions(-)

-- 
2.1.4

[Qemu-devel] [PATCH 1/5] trace: move qemu_trace_opts to trace/control.c

[Denis V. Lunev]

The patch also creates trace_opt_parse() helper in trace/control.c to reuse
this code in next patches for qemu-nbd and qemu-io.

The patch also makes trace_init_events() static, as this call is not used
outside the module anymore.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
---
 trace/control.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
 trace/control.h | 24 +++++++++++++-----------
 vl.c            | 37 +------------------------------------
 3 files changed, 57 insertions(+), 48 deletions(-)

diff --git a/trace/control.c b/trace/control.c
index d099f73..75fc731 100644
--- a/trace/control.c
+++ b/trace/control.c
@@ -20,11 +20,33 @@
 #include "qemu/log.h"
 #endif
 #include "qemu/error-report.h"
+#include "qemu/config-file.h"
 #include "monitor/monitor.h"
 
 int trace_events_enabled_count;
 bool trace_events_dstate[TRACE_EVENT_COUNT];
 
+QemuOptsList qemu_trace_opts = {
+    .name = "trace",
+    .implied_opt_name = "enable",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_trace_opts.head),
+    .desc = {
+        {
+            .name = "enable",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "events",
+            .type = QEMU_OPT_STRING,
+        },{
+            .name = "file",
+            .type = QEMU_OPT_STRING,
+        },
+        { /* end of list */ }
+    },
+};
+
+
 TraceEvent *trace_event_name(const char *name)
 {
     assert(name != NULL);
@@ -141,7 +163,7 @@ void trace_enable_events(const char *line_buf)
     }
 }
 
-void trace_init_events(const char *fname)
+static void trace_init_events(const char *fname)
 {
     Location loc;
     FILE *fp;
@@ -216,3 +238,23 @@ bool trace_init_backends(void)
 
     return true;
 }
+
+char *trace_opt_parse(const char *optarg, char *trace_file)
+{
+    QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("trace"),
+                                             optarg, true);
+    if (!opts) {
+        exit(1);
+    }
+    if (qemu_opt_get(opts, "enable")) {
+        trace_enable_events(qemu_opt_get(opts, "enable"));
+    }
+    trace_init_events(qemu_opt_get(opts, "events"));
+    if (trace_file) {
+        g_free(trace_file);
+    }
+    trace_file = g_strdup(qemu_opt_get(opts, "file"));
+    qemu_opts_del(opts);
+
+    return trace_file;
+}
diff --git a/trace/control.h b/trace/control.h
index e2ba6d4..942f9f5 100644
--- a/trace/control.h
+++ b/trace/control.h
@@ -160,17 +160,6 @@ static void trace_event_set_state_dynamic(TraceEvent *ev, bool state);
 bool trace_init_backends(void);
 
 /**
- * trace_init_events:
- * @events: Name of file with events to be enabled at startup; may be NULL.
- *          Corresponds to commandline option "-trace events=...".
- *
- * Read the list of enabled tracing events.
- *
- * Returns: Whether the backends could be successfully initialized.
- */
-void trace_init_events(const char *file);
-
-/**
  * trace_init_file:
  * @file:   Name of trace output file; may be NULL.
  *          Corresponds to commandline option "-trace file=...".
@@ -197,6 +186,19 @@ void trace_list_events(void);
  */
 void trace_enable_events(const char *line_buf);
 
+/**
+ * Definition of QEMU options describing trace subsystem configuration
+ */
+extern QemuOptsList qemu_trace_opts;
+
+/**
+ * trace_opt_parse:
+ * @optarg: A string argument of --trace command line argument
+ * @trace_file: current filename to save traces to
+ *
+ * Initialize tracing subsystem.
+ */
+char *trace_opt_parse(const char *optarg, char *trace_file);
 
 #include "trace/control-internal.h"
 
diff --git a/vl.c b/vl.c
index 2f74fe8..f715acf 100644
--- a/vl.c
+++ b/vl.c
@@ -262,26 +262,6 @@ static QemuOptsList qemu_sandbox_opts = {
     },
 };
 
-static QemuOptsList qemu_trace_opts = {
-    .name = "trace",
-    .implied_opt_name = "enable",
-    .head = QTAILQ_HEAD_INITIALIZER(qemu_trace_opts.head),
-    .desc = {
-        {
-            .name = "enable",
-            .type = QEMU_OPT_STRING,
-        },
-        {
-            .name = "events",
-            .type = QEMU_OPT_STRING,
-        },{
-            .name = "file",
-            .type = QEMU_OPT_STRING,
-        },
-        { /* end of list */ }
-    },
-};
-
 static QemuOptsList qemu_option_rom_opts = {
     .name = "option-rom",
     .implied_opt_name = "romfile",
@@ -3872,23 +3852,8 @@ int main(int argc, char **argv, char **envp)
                 xen_mode = XEN_ATTACH;
                 break;
             case QEMU_OPTION_trace:
-            {
-                opts = qemu_opts_parse_noisily(qemu_find_opts("trace"),
-                                               optarg, true);
-                if (!opts) {
-                    exit(1);
-                }
-                if (qemu_opt_get(opts, "enable")) {
-                    trace_enable_events(qemu_opt_get(opts, "enable"));
-                }
-                trace_init_events(qemu_opt_get(opts, "events"));
-                if (trace_file) {
-                    g_free(trace_file);
-                }
-                trace_file = g_strdup(qemu_opt_get(opts, "file"));
-                qemu_opts_del(opts);
+                trace_file = trace_opt_parse(optarg, trace_file);
                 break;
-            }
             case QEMU_OPTION_readconfig:
                 {
                     int ret = qemu_read_config_file(optarg);
-- 
2.1.4

[Qemu-devel] [PATCH 2/5] trace: enable tracing in qemu-io

[Denis V. Lunev]

Moving trace_init_backends() into trace_opt_parse() is not possible. This
should be called after daemonize() in vl.c.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
---
 qemu-io.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/qemu-io.c b/qemu-io.c
index d977a6e..6b5700f 100644
--- a/qemu-io.c
+++ b/qemu-io.c
@@ -18,6 +18,7 @@
 #include "qemu/option.h"
 #include "qemu/config-file.h"
 #include "qemu/readline.h"
+#include "qemu/log.h"
 #include "qapi/qmp/qstring.h"
 #include "qom/object_interfaces.h"
 #include "sysemu/block-backend.h"
@@ -253,7 +254,9 @@ static void usage(const char *name)
 "  -k, --native-aio     use kernel AIO implementation (on Linux only)\n"
 "  -t, --cache=MODE     use the given cache mode for the image\n"
 "  -d, --discard=MODE   use the given discard mode for the image\n"
-"  -T, --trace FILE     enable trace events listed in the given file\n"
+"  -T, --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
+"                       specify tracing options\n"
+"                       see qemu(1) man page for full description\n"
 "  -h, --help           display this help and exit\n"
 "  -V, --version        output version information and exit\n"
 "\n"
@@ -458,6 +461,7 @@ int main(int argc, char **argv)
     Error *local_error = NULL;
     QDict *opts = NULL;
     const char *format = NULL;
+    char *trace_file = NULL;
 
 #ifdef CONFIG_POSIX
     signal(SIGPIPE, SIG_IGN);
@@ -470,6 +474,7 @@ int main(int argc, char **argv)
 
     module_call_init(MODULE_INIT_QOM);
     qemu_add_opts(&qemu_object_opts);
+    qemu_add_opts(&qemu_trace_opts);
     bdrv_init();
 
     while ((c = getopt_long(argc, argv, sopt, lopt, &opt_index)) != -1) {
@@ -509,9 +514,7 @@ int main(int argc, char **argv)
             }
             break;
         case 'T':
-            if (!trace_init_backends()) {
-                exit(1); /* error message will have been printed */
-            }
+            trace_file = trace_opt_parse(optarg, trace_file);
             break;
         case 'V':
             printf("%s version %s\n", progname, QEMU_VERSION);
@@ -557,6 +560,12 @@ int main(int argc, char **argv)
         exit(1);
     }
 
+    if (!trace_init_backends()) {
+        exit(1);
+    }
+    trace_init_file(trace_file);
+    qemu_set_log(LOG_TRACE);
+
     /* initialize commands */
     qemuio_add_command(&quit_cmd);
     qemuio_add_command(&open_cmd);
-- 
2.1.4

[Qemu-devel] [PATCH 3/5] trace: enable tracing in qemu-nbd

[Denis V. Lunev]

Please 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: Eric Blake <eblake@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
---
 qemu-nbd.c    | 18 +++++++++++++++++-
 qemu-nbd.texi | 28 ++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/qemu-nbd.c b/qemu-nbd.c
index 6554f0a..cd29164 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -27,12 +27,14 @@
 #include "qemu/error-report.h"
 #include "qemu/config-file.h"
 #include "qemu/bswap.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>
@@ -88,6 +90,8 @@ 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"
+"  --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
+"                            specify tracing options\n"
 #ifdef __linux__
 "Kernel NBD client support:\n"
 "  -c, --connect=DEV         connect FILE to the local NBD device DEV\n"
@@ -470,7 +474,7 @@ int main(int argc, char **argv)
     off_t fd_size;
     QemuOpts *sn_opts = NULL;
     const char *sn_id_or_name = NULL;
-    const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:x:";
+    const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:x:T:";
     struct option lopt[] = {
         { "help", no_argument, NULL, 'h' },
         { "version", no_argument, NULL, 'V' },
@@ -498,6 +502,7 @@ 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;
@@ -518,6 +523,7 @@ 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.
@@ -531,6 +537,7 @@ 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) {
@@ -703,6 +710,9 @@ 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;
         }
     }
 
@@ -718,6 +728,12 @@ 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");
diff --git a/qemu-nbd.texi b/qemu-nbd.texi
index 9f23343..e6943ad 100644
--- a/qemu-nbd.texi
+++ b/qemu-nbd.texi
@@ -92,6 +92,34 @@ Display extra debugging information
 Display this help and exit
 @item -V, --version
 Display version information and exit
+@item -T, --trace [events=@var{file}][,file=@var{file}]
+@findex --trace
+
+Specify tracing options.
+
+@table @option
+@item [enable=]@var{pattern}
+Immediately enable events matching @var{pattern}.
+The file must contain one event name (as listed in the @file{trace-events} file)
+per line; globbing patterns are accepted too.  This option is only
+available if QEMU NBD has been compiled with the @var{simple}, @var{stderr}
+or @var{ftrace} tracing backend.  To specify multiple events or patterns,
+specify the @option{--trace} option multiple times.
+
+Use @code{--trace help} to print a list of names of trace points.
+
+@item events=@var{file}
+Immediately enable events listed in @var{file}.
+The file must contain one event name (as listed in the @file{trace-events} file)
+per line; globbing patterns are accepted too.  This option is only
+available if QEMU NBD has been compiled with the @var{simple}, @var{stderr} or
+@var{ftrace} tracing backend.
+
+@item file=@var{file}
+Log output traces to @var{file}.
+This option is only available if QEMU NBD has been compiled with
+the @var{simple} tracing backend.
+@end table
 @end table
 
 @c man end
-- 
2.1.4

[Qemu-devel] [PATCH 4/5] qemu-img: move common options parsing before commands processing

[Denis V. Lunev]

This is necessary to enable creation of common qemu-img options which will
be specified before command.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
---
 qemu-img.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index 4b56ad3..aa85b6c 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -3499,26 +3499,33 @@ int main(int argc, char **argv)
     if (argc < 2) {
         error_exit("Not enough arguments");
     }
-    cmdname = argv[1];
 
     qemu_add_opts(&qemu_object_opts);
     qemu_add_opts(&qemu_source_opts);
 
-    /* find the command */
-    for (cmd = img_cmds; cmd->name != NULL; cmd++) {
-        if (!strcmp(cmdname, cmd->name)) {
-            return cmd->handler(argc - 1, argv + 1);
+    while ((c = getopt_long(argc, argv, "+h", long_options, NULL)) != -1) {
+        switch (c) {
+        case 'h':
+            help();
+            return 0;
+        case 'v':
+            printf(QEMU_IMG_VERSION);
+            return 0;
         }
     }
 
-    c = getopt_long(argc, argv, "h", long_options, NULL);
+    cmdname = argv[optind];
 
-    if (c == 'h') {
-        help();
-    }
-    if (c == 'v') {
-        printf(QEMU_IMG_VERSION);
-        return 0;
+    /* reset getopt_long scanning */
+    argc -= optind;
+    argv += optind;
+    optind = 1;
+
+    /* find the command */
+    for (cmd = img_cmds; cmd->name != NULL; cmd++) {
+        if (!strcmp(cmdname, cmd->name)) {
+            return cmd->handler(argc, argv);
+        }
     }
 
     /* not found */
-- 
2.1.4

[Qemu-devel] [PATCH 5/5] trace: enable tracing in qemu-img

[Denis V. Lunev]

The command will work this way:
    qemu-img --trace qcow2* create -f qcow2 1.img 64G

Signed-off-by: Denis V. Lunev <den@openvz.org>
Suggested by: Daniel P. Berrange <berrange@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
---
 qemu-img.c    | 24 +++++++++++++++++++++---
 qemu-img.texi | 34 +++++++++++++++++++++++++++++++++-
 2 files changed, 54 insertions(+), 4 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index aa85b6c..3b069d8 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -31,6 +31,7 @@
 #include "qemu/config-file.h"
 #include "qemu/option.h"
 #include "qemu/error-report.h"
+#include "qemu/log.h"
 #include "qom/object_interfaces.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/block-backend.h"
@@ -38,6 +39,7 @@
 #include "block/blockjob.h"
 #include "block/qapi.h"
 #include "crypto/init.h"
+#include "trace/control.h"
 #include <getopt.h>
 
 #define QEMU_IMG_VERSION "qemu-img version " QEMU_VERSION QEMU_PKGVERSION \
@@ -87,7 +89,7 @@ static void QEMU_NORETURN help(void)
 {
     const char *help_msg =
            QEMU_IMG_VERSION
-           "usage: qemu-img command [command options]\n"
+           "usage: qemu-img [common options] command [command options]\n"
            "QEMU disk image utility\n"
            "\n"
            "Command syntax:\n"
@@ -156,10 +158,14 @@ static void QEMU_NORETURN help(void)
            "  '-f' first image format\n"
            "  '-F' second image format\n"
            "  '-s' run in Strict mode - fail on different image size or sector allocation\n";
+    const char *help_msg2 =
+           "Common options:\n"
+           "  '-T', --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
+           "       specify tracing options\n";
 
     printf("%s\nSupported formats:", help_msg);
     bdrv_iterate_format(format_print, NULL);
-    printf("\n");
+    printf("\n\n%s", help_msg2);
     exit(EXIT_SUCCESS);
 }
 
@@ -3473,10 +3479,12 @@ int main(int argc, char **argv)
     const img_cmd_t *cmd;
     const char *cmdname;
     Error *local_error = NULL;
+    char *trace_file = NULL;
     int c;
     static const struct option long_options[] = {
         {"help", no_argument, 0, 'h'},
         {"version", no_argument, 0, 'v'},
+        {"trace", required_argument, NULL, 'T'},
         {0, 0, 0, 0}
     };
 
@@ -3502,8 +3510,9 @@ int main(int argc, char **argv)
 
     qemu_add_opts(&qemu_object_opts);
     qemu_add_opts(&qemu_source_opts);
+    qemu_add_opts(&qemu_trace_opts);
 
-    while ((c = getopt_long(argc, argv, "+h", long_options, NULL)) != -1) {
+    while ((c = getopt_long(argc, argv, "+hT:", long_options, NULL)) != -1) {
         switch (c) {
         case 'h':
             help();
@@ -3511,6 +3520,9 @@ int main(int argc, char **argv)
         case 'v':
             printf(QEMU_IMG_VERSION);
             return 0;
+        case 'T':
+            trace_file = trace_opt_parse(optarg, trace_file);
+            break;
         }
     }
 
@@ -3521,6 +3533,12 @@ int main(int argc, char **argv)
     argv += optind;
     optind = 1;
 
+    if (!trace_init_backends()) {
+        exit(1);
+    }
+    trace_init_file(trace_file);
+    qemu_set_log(LOG_TRACE);
+
     /* find the command */
     for (cmd = img_cmds; cmd->name != NULL; cmd++) {
         if (!strcmp(cmdname, cmd->name)) {
diff --git a/qemu-img.texi b/qemu-img.texi
index afaebdd..36f4240 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -1,6 +1,6 @@
 @example
 @c man begin SYNOPSIS
-@command{qemu-img} @var{command} [@var{command} @var{options}]
+@command{qemu-img} [@var{common} @var{options}] @var{command} [@var{command} @var{options}]
 @c man end
 @end example
 
@@ -16,6 +16,38 @@ inconsistent state.
 
 @c man begin OPTIONS
 
+Common options:
+@table @option
+@item -T, --trace [events=@var{file}][,file=@var{file}]
+@findex --trace
+
+Specify tracing options.
+
+@table @option
+@item [enable=]@var{pattern}
+Immediately enable events matching @var{pattern}.
+The file must contain one event name (as listed in the @file{trace-events} file)
+per line; globbing patterns are accepted too.  This option is only
+available if QEMU IMG has been compiled with the @var{simple}, @var{stderr}
+or @var{ftrace} tracing backend.  To specify multiple events or patterns,
+specify the @option{--trace} option multiple times.
+
+Use @code{--trace help} to print a list of names of trace points.
+
+@item events=@var{file}
+Immediately enable events listed in @var{file}.
+The file must contain one event name (as listed in the @file{trace-events} file)
+per line; globbing patterns are accepted too.  This option is only
+available if QEMU IMG has been compiled with the @var{simple}, @var{stderr} or
+@var{ftrace} tracing backend.
+
+@item file=@var{file}
+Log output traces to @var{file}.
+This option is only available if QEMU IMG has been compiled with
+the @var{simple} tracing backend.
+@end table
+@end table
+
 The following commands are supported:
 
 @include qemu-img-cmds.texi
-- 
2.1.4

Re: [Qemu-devel] [PATCH 3/5] trace: enable tracing in qemu-nbd

[Eric Blake]

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On 06/02/2016 12:35 PM, Denis V. Lunev wrote:
> Please 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: Eric Blake <eblake@redhat.com>
> CC: Paolo Bonzini <pbonzini@redhat.com>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> ---
>  qemu-nbd.c    | 18 +++++++++++++++++-
>  qemu-nbd.texi | 28 ++++++++++++++++++++++++++++
>  2 files changed, 45 insertions(+), 1 deletion(-)
> 

> +"  --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
> +"                            specify tracing options\n"

> +++ b/qemu-nbd.texi
> @@ -92,6 +92,34 @@ Display extra debugging information
>  Display this help and exit
>  @item -V, --version
>  Display version information and exit
> +@item -T, --trace [events=@var{file}][,file=@var{file}]

Why do these two descriptions differ?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH 3/5] trace: enable tracing in qemu-nbd

[Denis V. Lunev]

On 06/03/2016 05:46 PM, Eric Blake wrote:
> On 06/02/2016 12:35 PM, Denis V. Lunev wrote:
>> Please 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: Eric Blake <eblake@redhat.com>
>> CC: Paolo Bonzini <pbonzini@redhat.com>
>> CC: Stefan Hajnoczi <stefanha@redhat.com>
>> CC: Kevin Wolf <kwolf@redhat.com>
>> ---
>>   qemu-nbd.c    | 18 +++++++++++++++++-
>>   qemu-nbd.texi | 28 ++++++++++++++++++++++++++++
>>   2 files changed, 45 insertions(+), 1 deletion(-)
>>
>> +"  --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
>> +"                            specify tracing options\n"
>> +++ b/qemu-nbd.texi
>> @@ -92,6 +92,34 @@ Display extra debugging information
>>   Display this help and exit
>>   @item -V, --version
>>   Display version information and exit
>> +@item -T, --trace [events=@var{file}][,file=@var{file}]
> Why do these two descriptions differ?
>
my fault. I have changed description several times. Man is correct

Re: [Qemu-devel] [PATCH 4/5] qemu-img: move common options parsing before commands processing

[Eric Blake]

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On 06/02/2016 12:35 PM, Denis V. Lunev wrote:
> This is necessary to enable creation of common qemu-img options which will
> be specified before command.
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: Eric Blake <eblake@redhat.com>
> CC: Paolo Bonzini <pbonzini@redhat.com>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> ---
>  qemu-img.c | 31 +++++++++++++++++++------------
>  1 file changed, 19 insertions(+), 12 deletions(-)
> 

> -    /* find the command */
> -    for (cmd = img_cmds; cmd->name != NULL; cmd++) {
> -        if (!strcmp(cmdname, cmd->name)) {
> -            return cmd->handler(argc - 1, argv + 1);
> +    while ((c = getopt_long(argc, argv, "+h", long_options, NULL)) != -1) {
> +        switch (c) {
> +        case 'h':
> +            help();
> +            return 0;
> +        case 'v':

Umm, how is 'v' supposed to be hit if it is not passed in the short
option string summary?  That is, 'qemu-img --version' will work, but
'qemu-img -v' won't; while both 'qemu-img --help' and 'qemu-img -h' work.

> +            printf(QEMU_IMG_VERSION);
> +            return 0;
>          }
>      }
>  
> -    c = getopt_long(argc, argv, "h", long_options, NULL);
> +    cmdname = argv[optind];
>  
> -    if (c == 'h') {
> -        help();
> -    }
> -    if (c == 'v') {

On the other hand, it seems to be a pre-existing bug.  Still, it's worth
fixing while you're touching this.

In addition to moving the option processing, you should also update the
documentation (both --help and man page).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH 5/5] trace: enable tracing in qemu-img

[Eric Blake]

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On 06/02/2016 12:35 PM, Denis V. Lunev wrote:
> The command will work this way:
>     qemu-img --trace qcow2* create -f qcow2 1.img 64G
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> Suggested by: Daniel P. Berrange <berrange@redhat.com>
> CC: Eric Blake <eblake@redhat.com>
> CC: Paolo Bonzini <pbonzini@redhat.com>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> ---
>  qemu-img.c    | 24 +++++++++++++++++++++---
>  qemu-img.texi | 34 +++++++++++++++++++++++++++++++++-
>  2 files changed, 54 insertions(+), 4 deletions(-)
> 

> @@ -87,7 +89,7 @@ static void QEMU_NORETURN help(void)
>  {
>      const char *help_msg =
>             QEMU_IMG_VERSION
> -           "usage: qemu-img command [command options]\n"
> +           "usage: qemu-img [common options] command [command options]\n"
>             "QEMU disk image utility\n"

This hunk belongs in the previous patch

>             "\n"
>             "Command syntax:\n"
> @@ -156,10 +158,14 @@ static void QEMU_NORETURN help(void)
>             "  '-f' first image format\n"
>             "  '-F' second image format\n"
>             "  '-s' run in Strict mode - fail on different image size or sector allocation\n";
> +    const char *help_msg2 =
> +           "Common options:\n"
> +           "  '-T', --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
> +           "       specify tracing options\n";

Part of this hunk belongs in the previous patch, along with mention of
-h/--help as a common option moved up to this area, and adding mention
of -v/--version (once you fix -v to actually work).


> +++ b/qemu-img.texi
> @@ -1,6 +1,6 @@
>  @example
>  @c man begin SYNOPSIS
> -@command{qemu-img} @var{command} [@var{command} @var{options}]
> +@command{qemu-img} [@var{common} @var{options}] @var{command} [@var{command} @var{options}]

Again, this hunk belongs in the previous commit.

>  @c man end
>  @end example
>  
> @@ -16,6 +16,38 @@ inconsistent state.
>  
>  @c man begin OPTIONS
>  
> +Common options:
> +@table @option
> +@item -T, --trace [events=@var{file}][,file=@var{file}]

As in patch 3, why does this synopsis vary from the --help output?

Rather than duplicating the same text in multiple .texi files, should we
put the text in a single sub-file then use inclusion to pull it in? That
way, if we ever tweak the common option parsing for --trace, updating
the one sub-file will update all 3 man pages (qemu, qemu-img, qemu-nbd).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH 5/5] trace: enable tracing in qemu-img

[Denis V. Lunev]

On 06/03/2016 05:55 PM, Eric Blake wrote:
> On 06/02/2016 12:35 PM, Denis V. Lunev wrote:
>> The command will work this way:
>>      qemu-img --trace qcow2* create -f qcow2 1.img 64G
>>
>> Signed-off-by: Denis V. Lunev <den@openvz.org>
>> Suggested by: Daniel P. Berrange <berrange@redhat.com>
>> CC: Eric Blake <eblake@redhat.com>
>> CC: Paolo Bonzini <pbonzini@redhat.com>
>> CC: Stefan Hajnoczi <stefanha@redhat.com>
>> CC: Kevin Wolf <kwolf@redhat.com>
>> ---
>>   qemu-img.c    | 24 +++++++++++++++++++++---
>>   qemu-img.texi | 34 +++++++++++++++++++++++++++++++++-
>>   2 files changed, 54 insertions(+), 4 deletions(-)
>>
>> @@ -87,7 +89,7 @@ static void QEMU_NORETURN help(void)
>>   {
>>       const char *help_msg =
>>              QEMU_IMG_VERSION
>> -           "usage: qemu-img command [command options]\n"
>> +           "usage: qemu-img [common options] command [command options]\n"
>>              "QEMU disk image utility\n"
> This hunk belongs in the previous patch
>
>>              "\n"
>>              "Command syntax:\n"
>> @@ -156,10 +158,14 @@ static void QEMU_NORETURN help(void)
>>              "  '-f' first image format\n"
>>              "  '-F' second image format\n"
>>              "  '-s' run in Strict mode - fail on different image size or sector allocation\n";
>> +    const char *help_msg2 =
>> +           "Common options:\n"
>> +           "  '-T', --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
>> +           "       specify tracing options\n";
> Part of this hunk belongs in the previous patch, along with mention of
> -h/--help as a common option moved up to this area, and adding mention
> of -v/--version (once you fix -v to actually work).
>
>
>> +++ b/qemu-img.texi
>> @@ -1,6 +1,6 @@
>>   @example
>>   @c man begin SYNOPSIS
>> -@command{qemu-img} @var{command} [@var{command} @var{options}]
>> +@command{qemu-img} [@var{common} @var{options}] @var{command} [@var{command} @var{options}]
> Again, this hunk belongs in the previous commit.
>
>>   @c man end
>>   @end example
>>   
>> @@ -16,6 +16,38 @@ inconsistent state.
>>   
>>   @c man begin OPTIONS
>>   
>> +Common options:
>> +@table @option
>> +@item -T, --trace [events=@var{file}][,file=@var{file}]
> As in patch 3, why does this synopsis vary from the --help output?
same mistake, have tossed these bits several times. Will fix.

> Rather than duplicating the same text in multiple .texi files, should we
> put the text in a single sub-file then use inclusion to pull it in? That
> way, if we ever tweak the common option parsing for --trace, updating
> the one sub-file will update all 3 man pages (qemu, qemu-img, qemu-nbd).
>
thanks a lot for a review!