netdev - [PATCH net-next 2/2] selftests: bpf: log direct file writes

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Date:   Tue,  5 Nov 2019 13:26:12 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, daniel@...earbox.net,
        oss-drivers@...ronome.com,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [PATCH net-next 2/2] selftests: bpf: log direct file writes

Recent changes to netdevsim moved creating and destroying
devices from netlink to sysfs. The sysfs writes have been
implemented as direct writes, without shelling out. This
is faster, but leaves no trace in the logs. Add explicit
logs to make debugging possible.

Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
---
 tools/testing/selftests/bpf/test_offload.py | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_offload.py b/tools/testing/selftests/bpf/test_offload.py
index 1afa22c88e42..8294ae3ffb3c 100755
--- a/tools/testing/selftests/bpf/test_offload.py
+++ b/tools/testing/selftests/bpf/test_offload.py
@@ -335,13 +335,22 @@ def bpftool_prog_load(sample, file_name, maps=[], prog_type="xdp", dev=None,
     """
     Class for netdevsim bus device and its attributes.
     """
+    @staticmethod
+    def ctrl_write(path, val):
+        fullpath = os.path.join("/sys/bus/netdevsim/", path)
+        try:
+            with open(fullpath, "w") as f:
+                f.write(val)
+        except OSError as e:
+            log("WRITE %s: %r" % (fullpath, val), -e.errno)
+            raise e
+        log("WRITE %s: %r" % (fullpath, val), 0)
 
     def __init__(self, port_count=1):
         addr = 0
         while True:
             try:
-                with open("/sys/bus/netdevsim/new_device", "w") as f:
-                    f.write("%u %u" % (addr, port_count))
+                self.ctrl_write("new_device", "%u %u" % (addr, port_count))
             except OSError as e:
                 if e.errno == errno.ENOSPC:
                     addr += 1
@@ -403,14 +412,13 @@ def bpftool_prog_load(sample, file_name, maps=[], prog_type="xdp", dev=None,
         return progs
 
     def remove(self):
-        with open("/sys/bus/netdevsim/del_device", "w") as f:
-            f.write("%u" % self.addr)
+        self.ctrl_write("del_device", "%u" % (self.addr, ))
         devs.remove(self)
 
     def remove_nsim(self, nsim):
         self.nsims.remove(nsim)
-        with open("/sys/bus/netdevsim/devices/netdevsim%u/del_port" % self.addr ,"w") as f:
-            f.write("%u" % nsim.port_index)
+        self.ctrl_write("devices/netdevsim%u/del_port" % (self.addr, ),
+                        "%u" % (nsim.port_index, ))
 
 class NetdevSim:
     """
-- 
2.23.0