[PATCH] net: dsa: loop: release netdev reference on registration failure

[PATCH] net: dsa: loop: release netdev reference on registration failure

[Wentao Liang]

dsa_loop_drv_probe() takes a reference on the CPU net_device with
dev_get_by_name() before calling dsa_register_switch(). The matching
dev_put() is only done in dsa_loop_drv_remove(), which the driver core
does not call after a failed probe, so every failed registration leaks
the reference.

Drop the reference when dsa_register_switch() fails.

Fixes: 98cd1552ea27 ("net: dsa: Mock-up driver")
Cc: stable@vger.kernel.org
Assisted-by: DeepSeek-V4.1-Flash and OpenAI Codex
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 drivers/net/dsa/dsa_loop.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/dsa/dsa_loop.c b/drivers/net/dsa/dsa_loop.c
index 0e35e9841b9b..fd02327b5a56 100644
--- a/drivers/net/dsa/dsa_loop.c
+++ b/drivers/net/dsa/dsa_loop.c
@@ -390,6 +390,8 @@ static int dsa_loop_drv_probe(struct mdio_device *mdiodev)
 	if (!ret)
 		dev_info(&mdiodev->dev, "%s: 0x%0x\n",
 			 pdata->name, pdata->enabled_ports);
+	else
+		dev_put(ps->netdev);
 
 	return ret;
 }
-- 
2.34.1

Re: [PATCH] net: dsa: loop: release netdev reference on registration failure

[netdev-bot+sinfo]

Hi!

This is an automated message. This series looks like a fix, but its
commit messages seem to be missing some information:

 - How the issue was discovered, e.g. hit in production, hit during
   development, syzbot report, manual code inspection, LLM or static
   analysis tool scan.

 - Whether the issue was actually triggered, or is only theoretical
   (e.g. found by code inspection). If it was triggered please include
   the symptoms, like the stack trace or error messages.

Please do not repost the series just to address the above. Instead,
reply to this email with the missing information, so that reviewers
can take it into account. If the series needs another revision for
other reasons, please include the information in the commit messages
then.

The evaluation is done by an LLM so it may be wrong, if you think
that is the case please reply and explain.

Re: [PATCH] net: dsa: loop: release netdev reference on registration failure

[Krzysztof Kozlowski]

On Tue, 03 Nov 2026 10:05:29 +0000, Wentao Liang wrote:
> dsa_loop_drv_probe() takes a reference on the CPU net_device with
> dev_get_by_name() before calling dsa_register_switch(). The matching
> dev_put() is only done in dsa_loop_drv_remove(), which the driver core
> does not call after a failed probe, so every failed registration leaks
> the reference.
> 
> Drop the reference when dsa_register_switch() fails.
> 
> Fixes: 98cd1552ea27 ("net: dsa: Mock-up driver")
> Cc: stable@vger.kernel.org
> Assisted-by: DeepSeek-V4.1-Flash and OpenAI Codex
> Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
> ---
>  drivers/net/dsa/dsa_loop.c | 2 ++
>  1 file changed, 2 insertions(+)
> 



Multiple things here:
1. Your team ignored completely previous feedback. Multiple times.

2. You use multiple identities with this email address, thus I doubt that we
   speak with an actual person.

3. Your bot does not even bother running checkpatch, right?

4. Nothing of this was reproduced nor tested.

5. Finally, the same feedback:
You sent multiple independent patches, to multiple independent
subsystems. The amount of these patches clearly suggest this was
AI generated and most likely not tested.

More importantly, you sent all this work without properly organizing
relevant patches into patchsets. This makes reviewing difficult
and might cause multiple reviewers to address the same issue.
Replying to the entire set is impossible and requires handling each
patch independently, instead of applying or discarding the set.
Maintainers also won't see the bigger picture of your work. Quite
worrying.

This is on the verge of hostile patch: bomb us with so many
contributions, we won't be able to handle them in efficient manner,
like responding ONCE to ask you to slow down.  Considering all this
is untested and LLM generated, I have even more doubts whether this
should be considered for review.

Please read kernel documentation BEFORE posting more work. It will
explain you how to identify subsystems, how to organize your work per
subsystem (so a patchset grouping multiple patches with a short cover
letter), how to document the issue discovery method and what was
or was not tested.

Best regards,
Krzysztof

Re: [PATCH] net: dsa: loop: release netdev reference on registration failure

[Andrew Lunn]

On Tue, Nov 03, 2026 at 10:05:29AM +0000, Wentao Liang wrote:
> dsa_loop_drv_probe() takes a reference on the CPU net_device with
> dev_get_by_name() before calling dsa_register_switch(). The matching
> dev_put() is only done in dsa_loop_drv_remove(), which the driver core
> does not call after a failed probe, so every failed registration leaks
> the reference.

Please read:

https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html

You must indicate which tree this is for.

And please think carefully about which tree you pick. Does the issue
actually bother anybody?

    Andrew

---
pw-bot: cr