Use small lock to protect resources related to ethernet.

[wangzhi-art]

Note: Please adhere to Contributing Guidelines.

Summary

Use small lock to protect resources related to ethernet.

Impact

The underlying implementation of Ethernet.

Testing

CI

[nuttxpr]

[Experimental Bot, please feedback here]

No, this PR does not fully meet the NuttX requirements as described. While it provides some information, it's severely lacking in detail and completeness.

Here's a breakdown of what's missing:

• Summary: "Use small lock to protect resources related to ethernet" is insufficient. It doesn't explain why this lock is necessary (bug fix? performance improvement? new feature enabling something else?), which resources are being protected, or how the locking mechanism is implemented.

• Impact: "The underlying implementation of Ethernet" is vague. It must address all the specific impact points listed in the template (user impact, build impact, hardware impact, documentation, security, compatibility). Simply saying "implementation change" doesn't convey any useful information for reviewers. For almost all changes, several of these will be "NO" - but that still needs to be explicitly stated.

• Testing: "CI" is not acceptable. Local testing is required before submitting a PR. The template specifically requests logs before and after the change to demonstrate the issue being fixed or the new functionality working. Relying solely on CI pushes the testing burden onto the project maintainers and delays the review process.

Example of a better Summary:

"Currently, access to the ethernet transmit buffer and descriptor list is not thread-safe, leading to data corruption under heavy load (see issue #123). This PR introduces a small mutex lock to protect these critical sections, ensuring exclusive access and preventing race conditions. The lock is acquired before any modifications to the buffer or descriptor list and released immediately afterwards. This change is also relevant to the nx_netdev application (see nuttx-apps PR #456)."

Example of a better Impact:

• Impact on user: NO
• Impact on build: NO
• Impact on hardware: Specific to ethernet controllers. Tested on the STM32F429I-DISC1 board.
• Impact on documentation: YES. Updated the networking documentation to describe the locking mechanism and its implications for driver developers.
• Impact on security: Potentially YES. By preventing data corruption, this fix mitigates a possible denial-of-service vulnerability.
• Impact on compatibility: NO.
• Anything else to consider: Performance impact of the lock needs to be monitored.

Example of better Testing:

• Build Host(s): Linux (Ubuntu 20.04), x86_64, GCC 9.4.0
• Target(s): sim:nsh

Testing logs before change:

[logs showing data corruption/errors in ethernet transmission]

Testing logs after change:

[logs showing correct ethernet operation under the same load]