[Qemu-devel] [RFC PATCH 1/3] vmstate: error hint for failed equal checks

[Halil Pasic]

In some cases a failing VMSTATE_*_EQUAL does not mean we detected a bug
(it's actually the best we can do). Especially in these cases a verbose
error message is required.

Let's introduce infrastructure for specifying a error hint to be used if
equal check fails.

Signed-off-by: Halil Pasic <address@hidden>
---
Macros come in part 2. Once we are happy with the macros
this two patches should be squashed into one. 
---
 include/migration/vmstate.h |  1 +
 migration/vmstate-types.c   | 36 +++++++++++++++++++++++++++++++-----
 2 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 66895623da..d90d9b12ca 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -200,6 +200,7 @@ typedef enum {
 
 struct VMStateField {
     const char *name;
+    const char *err_hint;
     size_t offset;
     size_t size;
     size_t start;
diff --git a/migration/vmstate-types.c b/migration/vmstate-types.c
index 7287c6baa6..84d0545a38 100644
--- a/migration/vmstate-types.c
+++ b/migration/vmstate-types.c
@@ -19,6 +19,7 @@
 #include "qemu/error-report.h"
 #include "qemu/queue.h"
 #include "trace.h"
+#include "qapi/error.h"
 
 /* bool */
 
@@ -118,6 +119,7 @@ const VMStateInfo vmstate_info_int32 = {
 static int get_int32_equal(QEMUFile *f, void *pv, size_t size,
                            VMStateField *field)
 {
+    Error *err = NULL;
     int32_t *v = pv;
     int32_t v2;
     qemu_get_sbe32s(f, &v2);
@@ -125,7 +127,11 @@ static int get_int32_equal(QEMUFile *f, void *pv, size_t 
size,
     if (*v == v2) {
         return 0;
     }
-    error_report("%" PRIx32 " != %" PRIx32, *v, v2);
+    error_setg(&err, "%" PRIx32 " != %" PRIx32, *v, v2);
+    if (field->err_hint) {
+        error_append_hint(&err, "%s\n", field->err_hint);
+    }
+    error_report_err(err);
     return -EINVAL;
 }
 
@@ -259,6 +265,7 @@ const VMStateInfo vmstate_info_uint32 = {
 static int get_uint32_equal(QEMUFile *f, void *pv, size_t size,
                             VMStateField *field)
 {
+    Error *err = NULL;
     uint32_t *v = pv;
     uint32_t v2;
     qemu_get_be32s(f, &v2);
@@ -266,7 +273,11 @@ static int get_uint32_equal(QEMUFile *f, void *pv, size_t 
size,
     if (*v == v2) {
         return 0;
     }
-    error_report("%" PRIx32 " != %" PRIx32, *v, v2);
+    error_setg(&err, "%" PRIx32 " != %" PRIx32, *v, v2);
+    if (field->err_hint) {
+        error_append_hint(&err, "%s\n", field->err_hint);
+    }
+    error_report_err(err);
     return -EINVAL;
 }
 
@@ -333,6 +344,7 @@ const VMStateInfo vmstate_info_nullptr = {
 static int get_uint64_equal(QEMUFile *f, void *pv, size_t size,
                             VMStateField *field)
 {
+    Error *err = NULL;
     uint64_t *v = pv;
     uint64_t v2;
     qemu_get_be64s(f, &v2);
@@ -340,7 +352,11 @@ static int get_uint64_equal(QEMUFile *f, void *pv, size_t 
size,
     if (*v == v2) {
         return 0;
     }
-    error_report("%" PRIx64 " != %" PRIx64, *v, v2);
+    error_setg(&err, "%" PRIx64 " != %" PRIx64, *v, v2);
+    if (field->err_hint) {
+        error_append_hint(&err, "%s\n", field->err_hint);
+    }
+    error_report_err(err);
     return -EINVAL;
 }
 
@@ -356,6 +372,7 @@ const VMStateInfo vmstate_info_uint64_equal = {
 static int get_uint8_equal(QEMUFile *f, void *pv, size_t size,
                            VMStateField *field)
 {
+    Error *err = NULL;
     uint8_t *v = pv;
     uint8_t v2;
     qemu_get_8s(f, &v2);
@@ -363,7 +380,11 @@ static int get_uint8_equal(QEMUFile *f, void *pv, size_t 
size,
     if (*v == v2) {
         return 0;
     }
-    error_report("%x != %x", *v, v2);
+    error_setg(&err, "%x != %x", *v, v2);
+    if (field->err_hint) {
+        error_append_hint(&err, "%s\n", field->err_hint);
+    }
+    error_report_err(err);
     return -EINVAL;
 }
 
@@ -379,6 +400,7 @@ const VMStateInfo vmstate_info_uint8_equal = {
 static int get_uint16_equal(QEMUFile *f, void *pv, size_t size,
                             VMStateField *field)
 {
+    Error *err = NULL;
     uint16_t *v = pv;
     uint16_t v2;
     qemu_get_be16s(f, &v2);
@@ -386,7 +408,11 @@ static int get_uint16_equal(QEMUFile *f, void *pv, size_t 
size,
     if (*v == v2) {
         return 0;
     }
-    error_report("%x != %x", *v, v2);
+    error_setg(&err, "%x != %x", *v, v2);
+    if (field->err_hint) {
+        error_append_hint(&err, "%s\n", field->err_hint);
+    }
+    error_report_err(err);
     return -EINVAL;
 }
 
-- 
2.11.2