[libvirt] [PATCH] virNumaSetPagePoolSize: Produce friendlier error message

[Martin Kletzander]

On Mon, Jun 08, 2015 at 02:41:05PM +0200, Michal Privoznik wrote:
>https://bugzilla.redhat.com/show_bug.cgi?id=1224587
>
>The function takes two important arguments (among many others): @node
>and @page_size. From these two a path under /sys is constructed. The
>path is then used to read and write the desired size of huge pages
>pool. However, if the path does not exists due to either @node or
>@page_size having nonexistent value (e.g. there's no such NUMA node or
>no page size like -2), an cryptic error message is produced:
>
>  virsh # allocpages --pagesize 2049 --pagecount 8 --cellno -2
>  error: Failed to open file '/sys/devices/system/node/node-2/hugepages/hugepages-2049kB/nr_hugepages': No such file or directory
>
>Add two more checks to catch this and therefore produce much more
>friendlier error messages.
>
>Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>---
> src/util/virnuma.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
>diff --git a/src/util/virnuma.c b/src/util/virnuma.c
>index 669192a..5807d8f 100644
>--- a/src/util/virnuma.c
>+++ b/src/util/virnuma.c
>@@ -849,9 +849,27 @@ virNumaSetPagePoolSize(int node,
>         goto cleanup;
>     }
>
>+    if (node != -1 && !virNumaNodeIsAvailable(node)) {
>+        virReportError(VIR_ERR_OPERATION_FAILED,
>+                       _("NUMA node %d is not available"),
>+                       node);
>+        goto cleanup;
>+    }
>+
>     if (virNumaGetHugePageInfoPath(&nr_path, node, page_size, "nr_hugepages") < 0)
>         goto cleanup;
>
>+    if (!virFileExists(nr_path)) {
>+        /* Strictly speaking, @nr_path contains both NUMA node and page size.
>+         * So if it doesn't exist it can be due to any of those two is wrong.
>+         * However, the existence of the node was checked a few lines above, so
>+         * it can be only page size here. */

Über-strictly speaking, unless you compile with both WITH_NUMACTL &&
HAVE_NUMA_BITMASK_ISBITSET then virNumaNodeIsAvailable() can pass for
invalid node in case of non-contiguous NUMA node numbers.

>+        virReportError(VIR_ERR_OPERATION_FAILED,
>+                       _("page size %u not available"),
>+                       page_size);
>+        goto cleanup;
>+    }
>+
>     /* Firstly check, if there's anything for us to do */
>     if (virFileReadAll(nr_path, 1024, &nr_buf) < 0)
>         goto cleanup;
>--
>2.3.6
>
>--
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