virtio-9p: 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).  Fix such a case in
v9fs_device_realize_common().

This commit is generated by command

    sed -n '/^virtio-9p$/,/^$/{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>
Acked-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200707165037.1026246-7-armbru@redhat.com>
[ERRP_AUTO_PROPAGATE() renamed to ERRP_GUARD(), and
auto-propagated-errp.cocci to errp-guard.cocci.  Commit message
tweaked again.]

2 files changed, 6 insertions, 7 deletions

diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index 54e012e..3107637 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -1479,10 +1479,10 @@ static void error_append_security_model_hint(Error *const *errp)
 
 static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse, Error **errp)
 {
+    ERRP_GUARD();
     const char *sec_model = qemu_opt_get(opts, "security_model");
     const char *path = qemu_opt_get(opts, "path");
     const char *multidevs = qemu_opt_get(opts, "multidevs");
-    Error *local_err = NULL;
 
     if (!sec_model) {
         error_setg(errp, "security_model property not set");
@@ -1516,11 +1516,10 @@ static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse, Error **errp)
             fse->export_flags &= ~V9FS_FORBID_MULTIDEVS;
             fse->export_flags &= ~V9FS_REMAP_INODES;
         } else {
-            error_setg(&local_err, "invalid multidevs property '%s'",
+            error_setg(errp, "invalid multidevs property '%s'",
                        multidevs);
-            error_append_hint(&local_err, "Valid options are: multidevs="
+            error_append_hint(errp, "Valid options are: multidevs="
                               "[remap|forbid|warn]\n");
-            error_propagate(errp, local_err);
             return -1;
         }
     }
@@ -1530,9 +1529,8 @@ static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse, Error **errp)
         return -1;
     }
 
-    if (fsdev_throttle_parse_opts(opts, &fse->fst, &local_err)) {
-        error_propagate_prepend(errp, local_err,
-                                "invalid throttle configuration: ");
+    if (fsdev_throttle_parse_opts(opts, &fse->fst, errp)) {
+        error_prepend(errp, "invalid throttle configuration: ");
         return -1;
     }
 
diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index 9755fba..2ffd96a 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -4011,6 +4011,7 @@ void pdu_submit(V9fsPDU *pdu, P9MsgHeader *hdr)
 int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t,
                                Error **errp)
 {
+    ERRP_GUARD();
     int i, len;
     struct stat stat;
     FsDriverEntry *fse;