[RFC v5 083/126] QMP: introduce ERRP_AUTO_PROPAGATE

[Vladimir Sementsov-Ogievskiy]

If we want to add some info to errp (by error_prepend() or
error_append_hint()), we must use the ERRP_AUTO_PROPAGATE macro.
Otherwise, this info will not be added when errp == &fatal_err
(the program will exit prior to the error_append_hint() or
error_prepend() call).  Fix such cases.

If we want to check error after errp-function call, we need to
introduce local_err and than propagate it to errp. Instead, use
ERRP_AUTO_PROPAGATE macro, benefits are:
1. No need of explicit error_propagate call
2. No need of explicit local_err variable: use errp directly
3. ERRP_AUTO_PROPAGATE leaves errp as is if it's not NULL or
   &error_fatel, this means that we don't break error_abort
   (we'll abort on error_set, not on error_propagate)

This commit (together with its neighbors) was generated by

for f in $(git grep -l errp \*.[ch]); do \
    spatch --sp-file scripts/coccinelle/auto-propagated-errp.cocci \
    --macro-file scripts/cocci-macro-file.h --in-place --no-show-diff $f; \
done;

then fix a bit of compilation problems: coccinelle for some reason
leaves several
f() {
    ...
    goto out;
    ...
    out:
}
patterns, with "out:" at function end.

then
./python/commit-per-subsystem.py MAINTAINERS "$(< auto-msg)"

(auto-msg was a file with this commit message)

Still, for backporting it may be more comfortable to use only the first
command and then do one huge commit.

Reported-by: Kevin Wolf <address@hidden>
Reported-by: Greg Kurz <address@hidden>
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 monitor/qmp-cmds.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
index c6faa3eaf0..2db3199a2e 100644
--- a/monitor/qmp-cmds.c
+++ b/monitor/qmp-cmds.c
@@ -126,9 +126,9 @@ void qmp_x_exit_preconfig(Error **errp)
 
 void qmp_cont(Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     BlockBackend *blk;
     BlockJob *job;
-    Error *local_err = NULL;
 
     /* if there is a dump in background, we should wait until the dump
      * finished */
@@ -161,9 +161,8 @@ void qmp_cont(Error **errp)
      * If there are no inactive block nodes (e.g. because the VM was just
      * paused rather than completing a migration), bdrv_inactivate_all() simply
      * doesn't do anything. */
-    bdrv_invalidate_cache_all(&local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    bdrv_invalidate_cache_all(errp);
+    if (*errp) {
         return;
     }
 
-- 
2.21.0