[libvirt] [PATCH v2 4.5/4 variant 1] util: Don't check if entries under /sys/fs/resctrl/info/ are directories

[Ján Tomko]

On Mon, Jan 29, 2018 at 05:45:44PM +0100, Martin Kletzander wrote:
>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: Martin Kletzander <mkletzan at redhat.com>
>---
> src/util/virresctrl.c | 26 ++++++++++++++------------
> 1 file changed, 14 insertions(+), 12 deletions(-)
>
>diff --git a/src/util/virresctrl.c b/src/util/virresctrl.c
>index 684cb22fd8a2..ad4294c26b1e 100644
>--- a/src/util/virresctrl.c
>+++ b/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 +432,28 @@ 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 - the kernel interface might've

non-fatal, I assume

>+             * 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;
>

ACK

Jan
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