util: Don't check if entries under /sys/fs/resctrl/(info/) are directories

We are skipping non-directories under /sys/fs/resctrl/(info/) since those are not
interesting for us.  However in tests it can sometimes happen that ent->d_type
is 0 instead of 4 (DT_DIR) for directories.

I've seen it fail on two machines.  Different machines, different systems, I
cannot reproduce it even using the same setup.  So one of the ways how to work
around this is call stat() on it.  The other one is not checking if it is a
directory since we'll find out eventually when we want to read some files
underneath it.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

src/util/virresctrl.c

@@ -410,10 +410,6 @@ virResctrlGetInfo(virResctrlInfoPtr resctrl)
 
     while ((rv = virDirRead(dirp, &ent, SYSFS_RESCTRL_PATH "/info")) > 0) {
         VIR_DEBUG("Parsing info type '%s'", ent->d_name);
-
-        if (ent->d_type != DT_DIR)
-            continue;
-
         if (ent->d_name[0] != 'L')
             continue;
 
@@ -436,19 +432,29 @@ virResctrlGetInfo(virResctrlInfoPtr resctrl)
         rv = virFileReadValueUint(&i_type->control.max_allocation,
                                   SYSFS_RESCTRL_PATH "/info/%s/num_closids",
                                   ent->d_name);
-        if (rv == -2)
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                           _("Cannot get num_closids from resctrl cache info"));
-        if (rv < 0)
+        if (rv == -2) {
+            /* The file doesn't exist, so it's unusable for us,
+             *  but we can scan further */
+            VIR_WARN("The path '" SYSFS_RESCTRL_PATH "/info/%s/num_closids' "
+                     "does not exist",
+                     ent->d_name);
+        } else if (rv < 0) {
+            /* Other failures are fatal, so just quit */
             goto cleanup;
+        }
 
         rv = virFileReadValueString(&i_type->cbm_mask,
                                     SYSFS_RESCTRL_PATH
                                     "/info/%s/cbm_mask",
                                     ent->d_name);
-        if (rv == -2)
+        if (rv == -2) {
+            /* If the previous file exists, so should this one.  Hence -2 is
+             * fatal in this case as well (errors out in next condition) - the
+             * kernel interface might've changed too much or something else is
+             * wrong. */
             virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                            _("Cannot get cbm_mask from resctrl cache info"));
+        }
         if (rv < 0)
             goto cleanup;
 
@@ -1169,9 +1175,6 @@ virResctrlAllocGetUnused(virResctrlInfoPtr resctrl)
         goto error;
 
     while ((rv = virDirRead(dirp, &ent, SYSFS_RESCTRL_PATH)) > 0) {
-        if (ent->d_type != DT_DIR)
-            continue;
-
         if (STREQ(ent->d_name, "info"))
             continue;