[PATCH net-next] selftests: drv-net: update the README with variants

[PATCH net-next] selftests: drv-net: update the README with variants

[Jakub Kicinski]

Test authors need to know about variants, existing tests don't use
them because variants are relatively recent.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: joe@dama.to
CC: shuah@kernel.org
CC: linux-kselftest@vger.kernel.org
---
 .../testing/selftests/drivers/net/README.rst  | 33 +++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/tools/testing/selftests/drivers/net/README.rst b/tools/testing/selftests/drivers/net/README.rst
index c94992acf10b..b26b364be534 100644
--- a/tools/testing/selftests/drivers/net/README.rst
+++ b/tools/testing/selftests/drivers/net/README.rst
@@ -253,6 +253,39 @@ By default the tests are expected to be able to run on
 single-interface systems. All tests which may disconnect ``NETIF``
 must be annotated with ``@ksft_disruptive``.
 
+ksft_variants
+~~~~~~~~~~~~~
+
+Use the ``@ksft_variants`` decorator to run a test with multiple sets
+of inputs as separate test cases. This avoids duplicating test functions
+that only differ in parameters.
+
+Parameters can be a single value, a tuple, or a ``KsftNamedVariant``
+(which gives an explicit name to the sub-case). The argument to the
+decorator can be a list or a generator.
+
+Example::
+
+  @ksft_variants([
+      KsftNamedVariant("main", False),
+      KsftNamedVariant("ctx", True),
+  ])
+  def resize_periodic(cfg, create_context):
+      # test body receives (cfg, create_context) where create_context
+      # is False for the "main" variant and True for "ctx"
+      pass
+
+or::
+
+  def _gro_variants():
+      for mode in ["sw", "hw"]:
+          for protocol in ["tcp4", "tcp6"]:
+              yield (mode, protocol)
+
+  @ksft_variants(_gro_variants())
+  def test(cfg, mode, protocol):
+      pass
+
 Running tests CI-style
 ======================
 
-- 
2.53.0

Re: [PATCH net-next] selftests: drv-net: update the README with variants

[Joe Damato]

On Mon, Mar 30, 2026 at 05:19:30PM -0700, Jakub Kicinski wrote:
> Test authors need to know about variants, existing tests don't use
> them because variants are relatively recent.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> CC: joe@dama.to
> CC: shuah@kernel.org
> CC: linux-kselftest@vger.kernel.org
> ---
>  .../testing/selftests/drivers/net/README.rst  | 33 +++++++++++++++++++
>  1 file changed, 33 insertions(+)

Reviewed-by: Joe Damato <joe@dama.to>

Re: [PATCH net-next] selftests: drv-net: update the README with variants

[patchwork-bot+netdevbpf]

Hello:

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

On Mon, 30 Mar 2026 17:19:30 -0700 you wrote:
> Test authors need to know about variants, existing tests don't use
> them because variants are relatively recent.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> CC: joe@dama.to
> CC: shuah@kernel.org
> CC: linux-kselftest@vger.kernel.org
> 
> [...]

Here is the summary with links:
  - [net-next] selftests: drv-net: update the README with variants
    https://git.kernel.org/netdev/net-next/c/f843687c3027

You are awesome, thank you!
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