From: Jakub Kicinski <jakub.kicinski@netronome.com>
Date: Tue, 5 Nov 2019 13:26:12 -0800
Subject: selftests: bpf: log direct file writes
Patch-mainline: v5.5-rc1
Git-commit: acceca8d2416bf866c5826240f9907cc91273f95
References: bsc#1177028

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@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Gary Lin <glin@suse.com>
---
 tools/testing/selftests/bpf/test_offload.py |   20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

--- a/tools/testing/selftests/bpf/test_offload.py
+++ b/tools/testing/selftests/bpf/test_offload.py
@@ -335,13 +335,22 @@ class NetdevSimDev:
     """
     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 @@ class NetdevSimDev:
         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:
     """