[Qemu-devel] [PATCH 2/3] Migration: Add lots of trace events

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Mostly on the load side, so that when we get a complaint about
a migration failure we can figure out what it didn't like.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/vmstate.c | 22 +++++++++++++++++++---
 savevm.c            | 10 +++++++---
 trace-events        | 11 ++++++++++-
 3 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/migration/vmstate.c b/migration/vmstate.c
index 2c0b135..7b8dc3f 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -75,14 +75,19 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
     VMStateField *field = vmsd->fields;
     int ret;
 
+    trace_vmstate_load_state(vmsd->name, version_id);
     if (version_id > vmsd->version_id) {
+        trace_vmstate_load_state_end(vmsd->name, "too new", -EINVAL);
         return -EINVAL;
     }
     if  (version_id < vmsd->minimum_version_id) {
         if (vmsd->load_state_old &&
             version_id >= vmsd->minimum_version_id_old) {
-            return vmsd->load_state_old(f, opaque, version_id);
+            ret = vmsd->load_state_old(f, opaque, version_id);
+            trace_vmstate_load_state_end(vmsd->name, "old path", ret);
+            return ret;
         }
+        trace_vmstate_load_state_end(vmsd->name, "too old", -EINVAL);
         return -EINVAL;
     }
     if (vmsd->pre_load) {
@@ -92,6 +97,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
         }
     }
     while (field->name) {
+        trace_vmstate_load_state_field(vmsd->name, field->name);
         if ((field->field_exists &&
              field->field_exists(opaque, version_id)) ||
             (!field->field_exists &&
@@ -134,9 +140,10 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
         return ret;
     }
     if (vmsd->post_load) {
-        return vmsd->post_load(opaque, version_id);
+        ret = vmsd->post_load(opaque, version_id);
     }
-    return 0;
+    trace_vmstate_load_state_end(vmsd->name, "end", ret);
+    return ret;
 }
 
 void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
@@ -193,6 +200,8 @@ static const VMStateDescription *
 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
                                    void *opaque)
 {
+    trace_vmstate_subsection_load(vmsd->name);
+
     while (qemu_peek_byte(f, 0) == QEMU_VM_SUBSECTION) {
         char idstr[256];
         int ret;
@@ -202,20 +211,24 @@ static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
         len = qemu_peek_byte(f, 1);
         if (len < strlen(vmsd->name) + 1) {
             /* subsection name has be be "section_name/a" */
+            trace_vmstate_subsection_load_bad(vmsd->name, "(short)");
             return 0;
         }
         size = qemu_peek_buffer(f, (uint8_t *)idstr, len, 2);
         if (size != len) {
+            trace_vmstate_subsection_load_bad(vmsd->name, "(peek fail)");
             return 0;
         }
         idstr[size] = 0;
 
         if (strncmp(vmsd->name, idstr, strlen(vmsd->name)) != 0) {
+            trace_vmstate_subsection_load_bad(vmsd->name, idstr);
             /* it don't have a valid subsection name */
             return 0;
         }
         sub_vmsd = vmstate_get_subsection(vmsd->subsections, idstr);
         if (sub_vmsd == NULL) {
+            trace_vmstate_subsection_load_bad(vmsd->name, "(lookup)");
             return -ENOENT;
         }
         qemu_file_skip(f, 1); /* subsection */
@@ -225,9 +238,12 @@ static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
 
         ret = vmstate_load_state(f, sub_vmsd, opaque, version_id);
         if (ret) {
+            trace_vmstate_subsection_load_bad(vmsd->name, "(child)");
             return ret;
         }
     }
+
+    trace_vmstate_subsection_load_good(vmsd->name);
     return 0;
 }
 
diff --git a/savevm.c b/savevm.c
index 48c2396..1cc0f02 100644
--- a/savevm.c
+++ b/savevm.c
@@ -674,7 +674,7 @@ int qemu_savevm_state_iterate(QEMUFile *f)
         qemu_put_be32(f, se->section_id);
 
         ret = se->ops->save_live_iterate(f, se->opaque);
-        trace_savevm_section_end(se->idstr, se->section_id);
+        trace_savevm_section_end(se->idstr, se->section_id, ret);
 
         if (ret < 0) {
             qemu_file_set_error(f, ret);
@@ -714,7 +714,7 @@ void qemu_savevm_state_complete(QEMUFile *f)
         qemu_put_be32(f, se->section_id);
 
         ret = se->ops->save_live_complete(f, se->opaque);
-        trace_savevm_section_end(se->idstr, se->section_id);
+        trace_savevm_section_end(se->idstr, se->section_id, ret);
         if (ret < 0) {
             qemu_file_set_error(f, ret);
             return;
@@ -741,7 +741,7 @@ void qemu_savevm_state_complete(QEMUFile *f)
         qemu_put_be32(f, se->version_id);
 
         vmstate_save(f, se);
-        trace_savevm_section_end(se->idstr, se->section_id);
+        trace_savevm_section_end(se->idstr, se->section_id, 0);
     }
 
     qemu_put_byte(f, QEMU_VM_EOF);
@@ -911,6 +911,7 @@ int qemu_loadvm_state(QEMUFile *f)
         char idstr[257];
         int len;
 
+        trace_qemu_loadvm_state_section(section_type);
         switch (section_type) {
         case QEMU_VM_SECTION_START:
         case QEMU_VM_SECTION_FULL:
@@ -922,6 +923,8 @@ int qemu_loadvm_state(QEMUFile *f)
             instance_id = qemu_get_be32(f);
             version_id = qemu_get_be32(f);
 
+            trace_qemu_loadvm_state_section_startfull(section_id, idstr,
+                                                      instance_id, version_id);
             /* Find savevm section */
             se = find_se(idstr, instance_id);
             if (se == NULL) {
@@ -958,6 +961,7 @@ int qemu_loadvm_state(QEMUFile *f)
         case QEMU_VM_SECTION_END:
             section_id = qemu_get_be32(f);
 
+            trace_qemu_loadvm_state_section_partend(section_id);
             QLIST_FOREACH(le, &loadvm_handlers, entry) {
                 if (le->section_id == section_id) {
                     break;
diff --git a/trace-events b/trace-events
index 8acbcce..1bf57b3 100644
--- a/trace-events
+++ b/trace-events
@@ -1133,8 +1133,11 @@ vmware_scratch_write(uint32_t index, uint32_t value) "index %d, value 0x%x"
 vmware_setmode(uint32_t w, uint32_t h, uint32_t bpp) "%dx%d @ %d bpp"
 
 # savevm.c
+qemu_loadvm_state_section(unsigned int section_type) "%d"
+qemu_loadvm_state_section_partend(uint32_t section_id) "%u"
+qemu_loadvm_state_section_startfull(uint32_t section_id, const char *idstr, uint32_t instance_id, uint32_t version_id) "%u(%s) %u %u"
 savevm_section_start(const char *id, unsigned int section_id) "%s, section_id %u"
-savevm_section_end(const char *id, unsigned int section_id) "%s, section_id %u"
+savevm_section_end(const char *id, unsigned int section_id, int ret) "%s, section_id %u -> %d"
 savevm_state_begin(void) ""
 savevm_state_iterate(void) ""
 savevm_state_complete(void) ""
@@ -1145,6 +1148,12 @@ qemu_announce_self_iter(const char *mac) "%s"
 
 # vmstate.c
 vmstate_load_field_error(const char *field, int ret) "field \"%s\" load failed, ret = %d"
+vmstate_load_state(const char *name, int version_id) "%s v%d"
+vmstate_load_state_end(const char *name, const char *reason, int val) "%s %s/%d"
+vmstate_load_state_field(const char *name, const char *field) "%s:%s"
+vmstate_subsection_load(const char *parent) "%s"
+vmstate_subsection_load_bad(const char *parent,  const char *sub) "%s: %s"
+vmstate_subsection_load_good(const char *parent) "%s"
 
 # qemu-file.c
 qemu_file_fclose(void) ""
-- 
2.1.0