[PATCH v3 2/8] tools/hotplug/Linux: re-factor add_to_bridge() in xen-network-common.sh

[Paul Durrant <paul@xen.org>]

From: Paul Durrant <pdurrant@amazon.com>

Remove duplication of 'ip link set dev'. It is perfectly fine to call it
even if the device has already been added to the bridge.

NOTE: This patch also adds code to write a debug log entry if the device
      was already on the bridge.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Wei Liu <wl@xen.org>

v3:
 - Re-factored from "tools/hotplug: add remove_from_bridge() and improve
   debug output" in v2
---
 tools/hotplug/Linux/xen-network-common.sh | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/tools/hotplug/Linux/xen-network-common.sh b/tools/hotplug/Linux/xen-network-common.sh
index 8dd3a62068..ec3bd4ec4a 100644
--- a/tools/hotplug/Linux/xen-network-common.sh
+++ b/tools/hotplug/Linux/xen-network-common.sh
@@ -126,16 +126,18 @@ add_to_bridge () {
     local bridge=$1
     local dev=$2
 
-    # Don't add $dev to $bridge if it's already on a bridge.
-    if [ -e "/sys/class/net/${bridge}/brif/${dev}" ]; then
-	ip link set dev ${dev} up || true
-	return
-    fi
-    if which brctl >&/dev/null; then
-        brctl addif ${bridge} ${dev}
+    # Don't add $dev to $bridge if it's already on the bridge.
+    if [ ! -e "/sys/class/net/${bridge}/brif/${dev}" ]; then
+        log debug "adding $dev to bridge $bridge"
+        if which brctl >&/dev/null; then
+            brctl addif ${bridge} ${dev}
+        else
+            ip link set ${dev} master ${bridge}
+        fi
     else
-        ip link set ${dev} master ${bridge}
+        log debug "$dev already on bridge $bridge"
     fi
+
     ip link set dev ${dev} up
 }
 
-- 
2.20.1