[networking] brctl command is run when bridge kernel module is loaded only

Previously, bridge information were collected even if bridge kernel module were not loaded.
brctl command requires and loads bridge and related kernel modules to accomplish its purporse.
This behaviour causes unexpected and unnecessary kernel module loading.

sosreport should not change the system configuration.

This patch will change this behaviour to run brctl command only if bridge module is loaded.

Closes #616

Signed-off-by: Keigo Noha <knoha@redhat.com>
Signed-off-by: Adam Stokes <adam.stokes@ubuntu.com>

2 files changed, 19 insertions, 7 deletions

diff --git a/sos/plugins/__init__.py b/sos/plugins/__init__.py
index 6731b285..b34c3bbc 100644
--- a/sos/plugins/__init__.py
+++ b/sos/plugins/__init__.py
@@ -662,6 +662,13 @@ class Plugin(object):
 
         return os.path.join(self.archive.get_archive_path(), outfn)
 
+    def is_module_loaded(self, module_name):
+        """Return whether specified moudle as module_name is loaded or not"""
+        if len(grep("^" + module_name + " ", "/proc/modules")) == 0:
+            return None
+        else:
+            return True
+
     # For adding output
     def add_alert(self, alertstring):
         """Add an alert to the collection of alerts for this plugin. These
diff --git a/sos/plugins/networking.py b/sos/plugins/networking.py
index f39f126b..c7ee76b5 100644
--- a/sos/plugins/networking.py
+++ b/sos/plugins/networking.py
@@ -191,13 +191,18 @@ class Networking(Plugin):
                     "ethtool -g "+eth
                 ])
 
-        brctl_file = self.get_cmd_output_now("brctl show")
-        if brctl_file:
-            for br_name in self.get_bridge_name(brctl_file):
-                self.add_cmd_output([
-                    "brctl showstp "+br_name,
-                    "brctl showmacs "+br_name
-                ])
+        # brctl command will load bridge and related kernel modules
+        # if those modules are not loaded at the time of brctl command running
+        # This behaviour causes an unexpected configuration change for system.
+        # sosreport should aovid such situation.
+        if self.is_module_loaded("bridge"):
+            brctl_file = self.get_cmd_output_now("brctl show")
+            if brctl_file:
+                for br_name in self.get_bridge_name(brctl_file):
+                    self.add_cmd_output([
+                            "brctl showstp "+br_name,
+                            "brctl showmacs "+br_name
+                    ])
 
         if self.get_option("traceroute"):
             self.add_cmd_output("/bin/traceroute -n %s" % self.trace_host)