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[Qemu-devel] [PATCH 1/5] migration/vmstate: renames in (load|save)_state

From: Halil Pasic
Subject: [Qemu-devel] [PATCH 1/5] migration/vmstate: renames in (load|save)_state
Date: Thu, 16 Feb 2017 13:11:36 +0100

The vmstate_(load|save)_state start out with an a void *opaque pointing
to some struct, and manipulate one or more elements of one field within
that struct.

First the field within the struct is pinpointed as opaque + offset, then
if this is a pointer the pointer is dereferenced to obtain a pointer to
the first element of the vmstate field. Pointers to further elements if
any are calculated as first_element + i * element_size (where i is the
zero based index of the element in question).

Currently base_addr and addr is used as a variable name for the pointer
to the first element and the pointer to the current element being
processed. This is suboptimal because base_addr is somewhat
counter-intuitive (because obtained as base + offset) and both base_addr
and addr not very descriptive (that we have a pointer should be clear
from the fact that it is declared as a pointer).

Let make things easier to understand by renaming base_addr to first_elem
and addr to curr_elem. This has the additional benefit of harmonizing
with other names within the scope (n_elems, vmstate_n_elems).

Signed-off-by: Halil Pasic <address@hidden>
Reviewed-by: Dr. David Alan Gilbert <address@hidden>

This patch roots in the difficulties I faced when trying to figure out
the code in question. In the meanwhile I'm quite fine with the current
names because I have it already figured out (after a couple of months
not looking on this code however, who knows). Thus my main motivation
is making things easier for the next new guy, but if the old guys say
not worth it I can very well accept that too.
 migration/vmstate.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/migration/vmstate.c b/migration/vmstate.c
index b4d8ae9..36efa80 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -116,21 +116,21 @@ int vmstate_load_state(QEMUFile *f, const 
VMStateDescription *vmsd,
              field->field_exists(opaque, version_id)) ||
             (!field->field_exists &&
              field->version_id <= version_id)) {
-            void *base_addr = vmstate_base_addr(opaque, field, true);
+            void *first_elem = vmstate_base_addr(opaque, field, true);
             int i, n_elems = vmstate_n_elems(opaque, field);
             int size = vmstate_size(opaque, field);
             for (i = 0; i < n_elems; i++) {
-                void *addr = base_addr + size * i;
+                void *curr_elem = first_elem + size * i;
                 if (field->flags & VMS_ARRAY_OF_POINTER) {
-                    addr = *(void **)addr;
+                    curr_elem = *(void **)curr_elem;
                 if (field->flags & VMS_STRUCT) {
-                    ret = vmstate_load_state(f, field->vmsd, addr,
+                    ret = vmstate_load_state(f, field->vmsd, curr_elem,
                 } else {
-                   ret = field->info->get(f, addr, size, field);
+                    ret = field->info->get(f, curr_elem, size, field);
                 if (ret >= 0) {
                     ret = qemu_file_get_error(f);
@@ -321,7 +321,7 @@ void vmstate_save_state(QEMUFile *f, const 
VMStateDescription *vmsd,
     while (field->name) {
         if (!field->field_exists ||
             field->field_exists(opaque, vmsd->version_id)) {
-            void *base_addr = vmstate_base_addr(opaque, field, false);
+            void *first_elem = vmstate_base_addr(opaque, field, false);
             int i, n_elems = vmstate_n_elems(opaque, field);
             int size = vmstate_size(opaque, field);
             int64_t old_offset, written_bytes;
@@ -329,18 +329,18 @@ void vmstate_save_state(QEMUFile *f, const 
VMStateDescription *vmsd,
             trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems);
             for (i = 0; i < n_elems; i++) {
-                void *addr = base_addr + size * i;
+                void *curr_elem = first_elem + size * i;
                 vmsd_desc_field_start(vmsd, vmdesc_loop, field, i, n_elems);
                 old_offset = qemu_ftell_fast(f);
                 if (field->flags & VMS_ARRAY_OF_POINTER) {
-                    addr = *(void **)addr;
+                    assert(curr_elem);
+                    curr_elem = *(void **)curr_elem;
                 if (field->flags & VMS_STRUCT) {
-                    vmstate_save_state(f, field->vmsd, addr, vmdesc_loop);
+                    vmstate_save_state(f, field->vmsd, curr_elem, vmdesc_loop);
                 } else {
-                    field->info->put(f, addr, size, field, vmdesc_loop);
+                    field->info->put(f, curr_elem, size, field, vmdesc_loop);
                 written_bytes = qemu_ftell_fast(f) - old_offset;

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