[PATCH v3 05/12] Devices.Device: add pause frames properties and methods

[Jan Tluka]

The Device class now provides following properties:
rx_pause_frames
tx_pause_frames

The property value is True if the pause frame setting is on or False
if it is turned off. The same applies when setting the property value.

The configuration of the pause frames is automatically restored to the
state before running a recipe.

Version 2:

Ethtool returns non-zero error code when the pause frames have the same
values as the values to be configured. To handle this I added a return
code check for this specific case.

Signed-off-by: Jan Tluka <jtluka(a)redhat.com&gt;
---
 lnst/Devices/Device.py | 109 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 108 insertions(+), 1 deletion(-)

diff --git a/lnst/Devices/Device.py b/lnst/Devices/Device.py
index 112a9276..30b82f06 100644
--- a/lnst/Devices/Device.py
+++ b/lnst/Devices/Device.py
@@ -16,11 +16,12 @@ import ethtool
 import pyroute2
 import logging
 import pprint
+import time
 from abc import ABCMeta
 from pyroute2.netlink.rtnl import ifinfmsg
 from lnst.Common.Logs import log_exc_traceback
 from lnst.Common.NetUtils import normalize_hwaddr
-from lnst.Common.ExecCmd import exec_cmd
+from lnst.Common.ExecCmd import exec_cmd, ExecCmdFail
 from lnst.Common.DeviceError import DeviceError, DeviceDeleted, DeviceDisabled
 from lnst.Common.DeviceError import DeviceConfigError, DeviceConfigValueError
 from lnst.Common.DeviceError import DeviceFeatureNotSupported
@@ -242,6 +243,13 @@ class Device(object, metaclass=DeviceMeta):
         if_data["adaptive_rx_coalescing"] = ad_rx_coal
         if_data["adaptive_tx_coalescing"] = ad_tx_coal
 
+        try:
+            rx_pause, tx_pause = self._read_pause_frames()
+        except DeviceError:
+            rx_pause, tx_pause = None, None
+        if_data["rx_pause"] = rx_pause
+        if_data["tx_pause"] = tx_pause
+
         return if_data
 
     def _vars(self):
@@ -289,6 +297,16 @@ class Device(object, metaclass=DeviceMeta):
         self._cleanup_data["adaptive_rx_coalescing"] = ad_rx_coal
         self._cleanup_data["adaptive_tx_coalescing"] = ad_tx_coal
 
+        try:
+            rx_pause, tx_pause = self._read_pause_frames()
+        except DeviceError:
+            rx_pause, tx_pause = None, None
+        self._cleanup_data.update(
+                {
+                    "rx_pause": rx_pause,
+                    "tx_pause": tx_pause
+                })
+
     def restore_original_data(self):
         """Restores initial configuration from stored
values"""
         if not self._cleanup_data:
@@ -309,6 +327,11 @@ class Device(object, metaclass=DeviceMeta):
         except DeviceError:
             pass
 
+        # the device needs to be up to configure the pause frame settings
+        self.up()
+        self.restore_pause_frames()
+        self.down()
+
         self._cleanup_data = None
 
     def _create(self):
@@ -654,6 +677,90 @@ class Device(object, metaclass=DeviceMeta):
         if (rx_val, tx_val) != (None, None):
             self._write_adaptive_coalescing(rx_val, tx_val)
 
+    @property
+    def rx_pause_frames(self):
+        return self._read_pause_frames()[0]
+
+    @rx_pause_frames.setter
+    def rx_pause_frames(self, value):
+        self._write_pause_frames(value, None)
+
+    @property
+    def tx_pause_frames(self):
+        return self._read_pause_frames()[1]
+
+    @tx_pause_frames.setter
+    def tx_pause_frames(self, value):
+        self._write_pause_frames(None, value)
+
+    def _read_pause_frames(self):
+        try:
+            res, _ = exec_cmd("ethtool -a %s" % self.name)
+        except:
+            raise DeviceFeatureNotSupported(
+                "No values for pause frames of %s." % self.name
+                )
+
+        # TODO: add autonegotiate
+        pause_settings = []
+        regex = "(RX|TX):.*(on|off)"
+
+        for line in res.split('\n'):
+            m = re.search(regex, line)
+            if m:
+                setting = True if m.group(2) == 'on' else False
+                pause_settings.append(setting)
+
+        if len(pause_settings) != 2:
+            raise Exception("Could not fetch pause frame settings. %s" % res)
+
+        return pause_settings
+
+    def _write_pause_frames(self, rx_val, tx_val):
+        ethtool_cmd = "ethtool -A {}".format(self.name)
+        ethtool_opts = ""
+
+        for feature, value in [('rx', rx_val), ('tx', tx_val)]:
+            if value is None:
+                continue
+
+            ethtool_opts += " {} {}".format(feature, 'on' if value else
'off')
+
+        if len(ethtool_opts) == 0:
+            return
+
+        try:
+            exec_cmd(ethtool_cmd + ethtool_opts)
+        except ExecCmdFail as e:
+            if e.get_retval() == 79:
+                raise DeviceConfigError(
+                    "Could not modify pause settings for %s." % self.name
+                )
+
+        timeout=5
+        while timeout > 0:
+            if self._pause_frames_match(rx_val, tx_val):
+                break
+            time.sleep(1)
+            timeout -= 1
+
+        if timeout == 0:
+            raise DeviceError("Pause frames not set!")
+
+    def _pause_frames_match(self, rx_expected, tx_expected):
+        rx_value, tx_value = self._read_pause_frames()
+        if ((rx_expected is not None and rx_expected != rx_value) or
+                (tx_expected is not None and tx_expected != tx_value)):
+            return False
+
+        return True
+
+    def restore_pause_frames(self):
+        rx_val = self._cleanup_data["rx_pause"]
+        tx_val = self._cleanup_data["tx_pause"]
+        if (rx_val, tx_val) != (None, None):
+            self._write_pause_frames(rx_val, tx_val)
+
     #TODO implement proper Route objects
     #consider the same as with tc?
     # def route_add(self, dest):
-- 
2.21.1