[PATCH net-next] selftests: net: prevent Python from buffering the output

[PATCH net-next] selftests: net: prevent Python from buffering the output

[Jakub Kicinski]

Make sure Python doesn't buffer the output, otherwise for some
tests we may see false positive timeouts in NIPA. NIPA thinks that
a machine has hung if the test doesn't print anything for 3min.
This is also nice to heave for running the tests manually,
especially in vng.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: shuah@kernel.org
CC: petrm@nvidia.com
CC: sdf@fomichev.me
---
 tools/testing/selftests/net/lib/py/ksft.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/net/lib/py/ksft.py b/tools/testing/selftests/net/lib/py/ksft.py
index 61287c203b6e..8e35ed12ed9e 100644
--- a/tools/testing/selftests/net/lib/py/ksft.py
+++ b/tools/testing/selftests/net/lib/py/ksft.py
@@ -32,6 +32,7 @@ KSFT_DISRUPTIVE = True
 
 
 def ksft_pr(*objs, **kwargs):
+    kwargs["flush"] = True
     print("#", *objs, **kwargs)
 
 
@@ -139,7 +140,7 @@ KSFT_DISRUPTIVE = True
         res += "." + str(case.__name__)
     if comment:
         res += " # " + comment
-    print(res)
+    print(res, flush=True)
 
 
 def ksft_flush_defer():
@@ -227,8 +228,8 @@ KSFT_DISRUPTIVE = True
 
     totals = {"pass": 0, "fail": 0, "skip": 0, "xfail": 0}
 
-    print("TAP version 13")
-    print("1.." + str(len(cases)))
+    print("TAP version 13", flush=True)
+    print("1.." + str(len(cases)), flush=True)
 
     global KSFT_RESULT
     cnt = 0
-- 
2.50.1

Re: [PATCH net-next] selftests: net: prevent Python from buffering the output

[Petr Machata]

Jakub Kicinski <kuba@kernel.org> writes:

> Make sure Python doesn't buffer the output, otherwise for some
> tests we may see false positive timeouts in NIPA. NIPA thinks that
> a machine has hung if the test doesn't print anything for 3min.
> This is also nice to heave for running the tests manually,
> especially in vng.
>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The flush keyword was introduced in 3.3, now out of support, so this
should be safe.

Reviewed-by: Petr Machata <petrm@nvidia.com>

Re: [PATCH net-next] selftests: net: prevent Python from buffering the output

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 16 Jul 2025 13:57:12 -0700 you wrote:
> Make sure Python doesn't buffer the output, otherwise for some
> tests we may see false positive timeouts in NIPA. NIPA thinks that
> a machine has hung if the test doesn't print anything for 3min.
> This is also nice to heave for running the tests manually,
> especially in vng.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> 
> [...]

Here is the summary with links:
  - [net-next] selftests: net: prevent Python from buffering the output
    https://git.kernel.org/netdev/net-next/c/797f080c463d

You are awesome, thank you!
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