[Qemu-devel] [PATCH for-2.8 v1 08/60] trace: provide mechanism for registering trace events

["Daniel P. Berrange" <berrange@redhat.com>]

Remove the notion of there being a single global array
of trace events, by introducing a method for registering
groups of events. The ID values will only be required to
be unique within the scope of a group of events.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 include/qemu/module.h                |  2 ++
 qemu-img.c                           |  1 +
 qemu-io.c                            |  1 +
 qemu-nbd.c                           |  1 +
 scripts/tracetool/format/events_c.py |  6 ++++++
 scripts/tracetool/format/events_h.py |  1 +
 trace/control-internal.h             |  5 ++++-
 trace/control.c                      | 38 +++++++++++++++++++++++++++++++-----
 trace/control.h                      |  1 +
 vl.c                                 |  2 ++
 10 files changed, 52 insertions(+), 6 deletions(-)

diff --git a/include/qemu/module.h b/include/qemu/module.h
index 2370708..c700961 100644
--- a/include/qemu/module.h
+++ b/include/qemu/module.h
@@ -44,6 +44,7 @@ typedef enum {
     MODULE_INIT_OPTS,
     MODULE_INIT_QAPI,
     MODULE_INIT_QOM,
+    MODULE_INIT_TRACE,
     MODULE_INIT_MAX
 } module_init_type;
 
@@ -51,6 +52,7 @@ typedef enum {
 #define opts_init(function) module_init(function, MODULE_INIT_OPTS)
 #define qapi_init(function) module_init(function, MODULE_INIT_QAPI)
 #define type_init(function) module_init(function, MODULE_INIT_QOM)
+#define trace_init(function) module_init(function, MODULE_INIT_TRACE)
 
 void register_module_init(void (*fn)(void), module_init_type type);
 void register_dso_module_init(void (*fn)(void), module_init_type type);
diff --git a/qemu-img.c b/qemu-img.c
index d2865a5..db97195 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -3822,6 +3822,7 @@ int main(int argc, char **argv)
     signal(SIGPIPE, SIG_IGN);
 #endif
 
+    module_call_init(MODULE_INIT_TRACE);
     error_set_progname(argv[0]);
     qemu_init_exec_dir(argv[0]);
 
diff --git a/qemu-io.c b/qemu-io.c
index db129ea..23a229f 100644
--- a/qemu-io.c
+++ b/qemu-io.c
@@ -467,6 +467,7 @@ int main(int argc, char **argv)
     signal(SIGPIPE, SIG_IGN);
 #endif
 
+    module_call_init(MODULE_INIT_TRACE);
     progname = basename(argv[0]);
     qemu_init_exec_dir(argv[0]);
 
diff --git a/qemu-nbd.c b/qemu-nbd.c
index e3571c2..ea1beed 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -533,6 +533,7 @@ int main(int argc, char **argv)
     sa_sigterm.sa_handler = termsig_handler;
     sigaction(SIGTERM, &sa_sigterm, NULL);
 
+    module_call_init(MODULE_INIT_TRACE);
     qcrypto_init(&error_fatal);
 
     module_call_init(MODULE_INIT_QOM);
diff --git a/scripts/tracetool/format/events_c.py b/scripts/tracetool/format/events_c.py
index 4012063..9203377 100644
--- a/scripts/tracetool/format/events_c.py
+++ b/scripts/tracetool/format/events_c.py
@@ -42,3 +42,9 @@ def generate(events, backend):
 
     out('};',
         '')
+
+    out('void trace_register_events(void)',
+        '{',
+        '    trace_event_register_group(trace_events, TRACE_EVENT_COUNT);',
+        '}',
+        'trace_init(trace_register_events)')
diff --git a/scripts/tracetool/format/events_h.py b/scripts/tracetool/format/events_h.py
index a9da60b..291c183 100644
--- a/scripts/tracetool/format/events_h.py
+++ b/scripts/tracetool/format/events_h.py
@@ -56,5 +56,6 @@ def generate(events, backend):
         out('#define TRACE_%s_ENABLED %d' % (e.name.upper(), enabled))
 
     out('#include "trace/event-internal.h"',
+        'void trace_register_events(void);',
         '',
         '#endif  /* TRACE__GENERATED_EVENTS_H */')
diff --git a/trace/control-internal.h b/trace/control-internal.h
index 7f31e39..e95b031 100644
--- a/trace/control-internal.h
+++ b/trace/control-internal.h
@@ -15,7 +15,6 @@
 #include "qom/cpu.h"
 
 
-extern TraceEvent trace_events[];
 extern uint16_t trace_events_dstate[];
 extern int trace_events_enabled_count;
 
@@ -88,4 +87,8 @@ static inline bool trace_event_get_vcpu_state_dynamic(CPUState *vcpu,
     return trace_event_get_vcpu_state_dynamic_by_vcpu_id(vcpu, id);
 }
 
+
+void trace_event_register_group(TraceEvent *events,
+                                size_t nevents);
+
 #endif /* TRACE__CONTROL_INTERNAL_H */
diff --git a/trace/control.c b/trace/control.c
index 7ba171b..4847a51 100644
--- a/trace/control.c
+++ b/trace/control.c
@@ -25,6 +25,15 @@
 #include "monitor/monitor.h"
 
 int trace_events_enabled_count;
+
+typedef struct TraceEventGroup {
+    TraceEvent *events;
+    size_t nevents;
+} TraceEventGroup;
+
+static TraceEventGroup *event_groups;
+static size_t nevent_groups;
+
 /*
  * Interpretation depends on wether the event has the 'vcpu' property:
  * - false: Boolean value indicating whether the event is active.
@@ -55,6 +64,16 @@ QemuOptsList qemu_trace_opts = {
 };
 
 
+void trace_event_register_group(TraceEvent *events,
+                                size_t nevents)
+{
+    event_groups = g_renew(TraceEventGroup, event_groups, nevent_groups + 1);
+    event_groups[nevent_groups].events = events;
+    event_groups[nevent_groups].nevents = nevents;
+    nevent_groups++;
+}
+
+
 TraceEvent *trace_event_name(const char *name)
 {
     assert(name != NULL);
@@ -105,6 +124,7 @@ static bool pattern_glob(const char *pat, const char *ev)
 void trace_event_iter_init(TraceEventIter *iter, const char *pattern)
 {
     iter->event = 0;
+    iter->group = 0;
     iter->pattern = pattern;
 }
 
@@ -112,18 +132,26 @@ TraceEvent *trace_event_iter_next(TraceEventIter *iter)
 {
     TraceEvent *ev;
 
-    if (iter->event >= TRACE_EVENT_COUNT) {
+    if (iter->group >= nevent_groups ||
+        iter->event >= event_groups[iter->group].nevents) {
         return NULL;
     }
 
-    ev = &(trace_events[iter->event]);
+    ev = &(event_groups[iter->group].events[iter->event]);
 
     do {
         iter->event++;
-    } while (iter->event < TRACE_EVENT_COUNT &&
+        if (iter->event >= event_groups[iter->group].nevents) {
+            iter->event = 0;
+            iter->group++;
+        }
+    } while (iter->group < nevent_groups &&
+             iter->event < event_groups[iter->group].nevents &&
              iter->pattern &&
-             !pattern_glob(iter->pattern,
-                           trace_event_get_name(&(trace_events[iter->event]))));
+             !pattern_glob(
+                 iter->pattern,
+                 trace_event_get_name(
+                     &(event_groups[iter->group].events[iter->event]))));
 
     return ev;
 }
diff --git a/trace/control.h b/trace/control.h
index 3f00adc..81471ad 100644
--- a/trace/control.h
+++ b/trace/control.h
@@ -15,6 +15,7 @@
 
 typedef struct TraceEventIter {
     size_t event;
+    size_t group;
     const char *pattern;
 } TraceEventIter;
 
diff --git a/vl.c b/vl.c
index c4eeaff..f65deca 100644
--- a/vl.c
+++ b/vl.c
@@ -2964,6 +2964,8 @@ int main(int argc, char **argv, char **envp)
     Error *err = NULL;
     bool list_data_dirs = false;
 
+    module_call_init(MODULE_INIT_TRACE);
+
     qemu_init_cpu_loop();
     qemu_mutex_lock_iothread();
 
-- 
2.7.4