xen: Use ERRP_GUARD()

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

If we want to add some info to errp (by error_prepend() or
error_append_hint()), we must use the ERRP_GUARD() macro.
Otherwise, this info will not be added when errp == &error_fatal
(the program will exit prior to the error_append_hint() or
error_prepend() call).  No such cases are being fixed here.

This commit is generated by command

    sed -n '/^X86 Xen CPUs$/,/^$/{s/^F: //p}' MAINTAINERS | \
    xargs git ls-files | grep '\.[hc]$' | \
    xargs spatch \
        --sp-file scripts/coccinelle/errp-guard.cocci \
        --macro-file scripts/cocci-macro-file.h \
        --in-place --no-show-diff --max-width 80

Reported-by: Kevin Wolf <kwolf@redhat.com>
Reported-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200707165037.1026246-9-armbru@redhat.com>
[ERRP_AUTO_PROPAGATE() renamed to ERRP_GUARD(), and
auto-propagated-errp.cocci to errp-guard.cocci.  Commit message
tweaked again.]

1 files changed, 9 insertions, 8 deletions

diff --git a/hw/xen/xen_pt_config_init.c b/hw/xen/xen_pt_config_init.c
index d0d7c720a6..c8724cc7c8 100644
--- a/hw/xen/xen_pt_config_init.c
+++ b/hw/xen/xen_pt_config_init.c
@@ -2008,8 +2008,8 @@ static void xen_pt_config_reg_init(XenPCIPassthroughState *s,
 
 void xen_pt_config_init(XenPCIPassthroughState *s, Error **errp)
 {
+    ERRP_GUARD();
     int i, rc;
-    Error *err = NULL;
 
     QLIST_INIT(&s->reg_grps);
 
@@ -2067,13 +2067,14 @@ void xen_pt_config_init(XenPCIPassthroughState *s, Error **errp)
 
                 /* initialize capability register */
                 for (j = 0; regs->size != 0; j++, regs++) {
-                    xen_pt_config_reg_init(s, reg_grp_entry, regs, &err);
-                    if (err) {
-                        error_append_hint(&err, "Failed to init register %d"
-                                " offsets 0x%x in grp_type = 0x%x (%d/%zu)", j,
-                                regs->offset, xen_pt_emu_reg_grps[i].grp_type,
-                                i, ARRAY_SIZE(xen_pt_emu_reg_grps));
-                        error_propagate(errp, err);
+                    xen_pt_config_reg_init(s, reg_grp_entry, regs, errp);
+                    if (*errp) {
+                        error_append_hint(errp, "Failed to init register %d"
+                                          " offsets 0x%x in grp_type = 0x%x (%d/%zu)",
+                                          j,
+                                          regs->offset,
+                                          xen_pt_emu_reg_grps[i].grp_type,
+                                          i, ARRAY_SIZE(xen_pt_emu_reg_grps));
                         xen_pt_config_delete(s);
                         return;
                     }