[RFC v5 085/126] Tracing: 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>
---
 trace/qmp.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/trace/qmp.c b/trace/qmp.c
index 38246e1aa6..05335f2da4 100644
--- a/trace/qmp.c
+++ b/trace/qmp.c
@@ -70,7 +70,7 @@ TraceEventInfoList *qmp_trace_event_get_state(const char 
*name,
                                               bool has_vcpu, int64_t vcpu,
                                               Error **errp)
 {
-    Error *err = NULL;
+    ERRP_AUTO_PROPAGATE();
     TraceEventInfoList *events = NULL;
     TraceEventIter iter;
     TraceEvent *ev;
@@ -78,9 +78,8 @@ TraceEventInfoList *qmp_trace_event_get_state(const char 
*name,
     CPUState *cpu;
 
     /* Check provided vcpu */
-    cpu = get_cpu(has_vcpu, vcpu, &err);
-    if (err) {
-        error_propagate(errp, err);
+    cpu = get_cpu(has_vcpu, vcpu, errp);
+    if (*errp) {
         return NULL;
     }
 
@@ -135,16 +134,15 @@ void qmp_trace_event_set_state(const char *name, bool 
enable,
                                bool has_vcpu, int64_t vcpu,
                                Error **errp)
 {
-    Error *err = NULL;
+    ERRP_AUTO_PROPAGATE();
     TraceEventIter iter;
     TraceEvent *ev;
     bool is_pattern = trace_event_is_pattern(name);
     CPUState *cpu;
 
     /* Check provided vcpu */
-    cpu = get_cpu(has_vcpu, vcpu, &err);
-    if (err) {
-        error_propagate(errp, err);
+    cpu = get_cpu(has_vcpu, vcpu, errp);
+    if (*errp) {
         return;
     }
 
-- 
2.21.0