[Xen-devel] [PATCH v2] libxenstat: handle renamed VIFs

[Jacek Konieczny <jajcus@xxxxxxxxxx>]

Before trying to parse network interface name as 'vif*.*'
try to get the domid and network number from sysfs.

Fixes xentop output for domains with VIF renamed through the
'vifname' xl option.

Signed-off-by: Jacek Konieczny <jajcus@xxxxxxxxxx>

---
Changed since v1:
  * get_iface_domid_network() return value comment fixed
---
 tools/xenstat/libxenstat/src/xenstat_linux.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/tools/xenstat/libxenstat/src/xenstat_linux.c 
b/tools/xenstat/libxenstat/src/xenstat_linux.c
index 24335e1..7fdf70a 100644
--- a/tools/xenstat/libxenstat/src/xenstat_linux.c
+++ b/tools/xenstat/libxenstat/src/xenstat_linux.c
@@ -233,6 +233,29 @@ int parseNetDevLine(char *line, char *iface, unsigned long 
long *rxBytes, unsign
        return 0;
 }
 
+/* Find out the domid and network number given an interface name.
+ * Return 0 if the iface cannot be recognized as a Xen VIF. */
+static int get_iface_domid_network(const char *iface, unsigned int *domid_p, 
unsigned int *netid_p)
+{
+       char nodename_path[48];
+       FILE * nodename_file;
+       int ret;
+
+       snprintf(nodename_path, 48, "/sys/class/net/%s/device/nodename", iface);
+       nodename_file = fopen(nodename_path, "r");
+       if (nodename_file != NULL) {
+               ret = fscanf(nodename_file, "backend/vif/%u/%u", domid_p, 
netid_p);
+               fclose(nodename_file);
+               if (ret == 2)
+                       return 1;
+       }
+
+       if (sscanf(iface, "vif%u.%u", domid_p, netid_p) == 2)
+               return 1;
+
+       return 0;
+}
+
 /* Collect information about networks */
 int xenstat_collect_networks(xenstat_node * node)
 {
@@ -309,8 +332,7 @@ int xenstat_collect_networks(xenstat_node * node)
                        }
                }
                else /* Otherwise we need to preserve old behaviour */
-               if (strstr(iface, "vif") != NULL) {
-                       sscanf(iface, "vif%u.%u", &domid, &net.id);
+               if (get_iface_domid_network(iface, &domid, &net.id)) {
 
                        net.tbytes = txBytes;
                        net.tpackets = txPackets;
-- 
1.9.0


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