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

[Martin Kletzander]

On Mon, Jan 29, 2018 at 05:54:03PM +0100, Ján Tomko wrote:
>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
>

No, it really is fatal, it's just that it errors out in the next
condition, which looks ugly, I'll fix the comment at least, since
changing the code would need changes in later parts as well in order to
stay consistent.

Thanks for the review.

>>+             * 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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