linux-kernel - [PATCH net-next v7 1/3] selftests: drv-net: add helper/wrapper for bpftrace

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Message-Id: <20250714-netpoll_test-v7-1-c0220cfaa63e@debian.org>
Date: Mon, 14 Jul 2025 02:56:48 -0700
From: Breno Leitao <leitao@...ian.org>
To: Andrew Lunn <andrew+netdev@...n.ch>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Shuah Khan <shuah@...nel.org>, Simon Horman <horms@...nel.org>
Cc: linux-kernel@...r.kernel.org, netdev@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, 
 Willem de Bruijn <willemdebruijn.kernel@...il.com>, bpf@...r.kernel.org, 
 kernel-team@...a.com, Breno Leitao <leitao@...ian.org>
Subject: [PATCH net-next v7 1/3] selftests: drv-net: add helper/wrapper for
 bpftrace

From: Jakub Kicinski <kuba@...nel.org>

bpftrace is very useful for low level driver testing. perf or trace-cmd
would also do for collecting data from tracepoints, but they require
much more post-processing.

Add a wrapper for running bpftrace and sanitizing its output.
bpftrace has JSON output, which is great, but it prints loose objects
and in a slightly inconvenient format. We have to read the objects
line by line, and while at it return them indexed by the map name.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Reviewed-by: Breno Leitao <leitao@...ian.org>
Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 .../selftests/drivers/net/lib/py/__init__.py       |  4 +--
 tools/testing/selftests/net/lib/py/utils.py        | 33 ++++++++++++++++++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/lib/py/__init__.py b/tools/testing/selftests/drivers/net/lib/py/__init__.py
index 39968bc3df43e..8711c67ad658a 100644
--- a/tools/testing/selftests/drivers/net/lib/py/__init__.py
+++ b/tools/testing/selftests/drivers/net/lib/py/__init__.py
@@ -14,8 +14,8 @@ try:
     from net.lib.py import EthtoolFamily, NetdevFamily, NetshaperFamily, \
         NlError, RtnlFamily, DevlinkFamily
     from net.lib.py import CmdExitFailure
-    from net.lib.py import bkg, cmd, defer, ethtool, fd_read_timeout, ip, \
-        rand_port, tool, wait_port_listen, bpftool
+    from net.lib.py import bkg, cmd, bpftool, bpftrace, defer, ethtool, \
+        fd_read_timeout, ip, rand_port, tool, wait_port_listen
     from net.lib.py import fd_read_timeout
     from net.lib.py import KsftSkipEx, KsftFailEx, KsftXfailEx
     from net.lib.py import ksft_disruptive, ksft_exit, ksft_pr, ksft_run, \
diff --git a/tools/testing/selftests/net/lib/py/utils.py b/tools/testing/selftests/net/lib/py/utils.py
index acf0e2c386144..5950a643a5336 100644
--- a/tools/testing/selftests/net/lib/py/utils.py
+++ b/tools/testing/selftests/net/lib/py/utils.py
@@ -189,6 +189,39 @@ def ethtool(args, json=None, ns=None, host=None):
     return tool('ethtool', args, json=json, ns=ns, host=host)
 
 
+def bpftrace(expr, json=None, ns=None, host=None, timeout=None):
+    """
+    Run bpftrace and return map data (if json=True).
+    The output of bpftrace is inconvenient, so the helper converts
+    to a dict indexed by map name, e.g.:
+     {
+       "@":     { ... },
+       "@map2": { ... },
+     }
+    """
+    cmd_arr = ['bpftrace']
+    # Throw in --quiet if json, otherwise the output has two objects
+    if json:
+        cmd_arr += ['-f', 'json', '-q']
+    if timeout:
+        expr += ' interval:s:' + str(timeout) + ' { exit(); }'
+    cmd_arr += ['-e', expr]
+    cmd_obj = cmd(cmd_arr, ns=ns, host=host, shell=False)
+    if json:
+        # bpftrace prints objects as lines
+        ret = {}
+        for l in cmd_obj.stdout.split('\n'):
+            if not l.strip():
+                continue
+            one = _json.loads(l)
+            if one.get('type') != 'map':
+                continue
+            for k, v in one["data"].items():
+                ret[k] = v
+        return ret
+    return cmd_obj
+
+
 def rand_port(type=socket.SOCK_STREAM):
     """
     Get a random unprivileged port.

-- 
2.47.1