Bugfix issue 946

[uniqueni]

问题描述

当前的 getBestGidIndex() 函数会选择第一个符合条件的 GID（IPv4-mapped + RoCE v2 或 IB 类型）。但在有多个符合条件的 GID 时，可能会选到不属于本机网络接口的 GID。

实际场景：

GID[3]: ::ffff:26.208.8.250, RoCE v2 (不是本机 IP)
GID[7]: ::ffff:26.208.8.252, RoCE v2 (本机 eth1 的 IP)
当前逻辑会选择 GID[3] 并立即返回，但实际应该选择 GID[7]。

###解决方案
我考虑了两种修复方式：
方式一：从 sysfs 读取网络设备信息（已采用）

• 读取 /sys/class/infiniband/{dev}/ports/{port}/gid_attrs/ndevs/{index}
• 选择有关联网络设备的 GID（如 "eth1"）
• 参考了 show_gids.sh https://gist.github.com/aagontuk/6aaee1ef908a0c3341ee0cac7c540fcc 脚本的实现
• 更加通用

方式二：匹配本机 IP 地址

• 提取 GID 中的 IPv4 地址
• 通过 getifaddrs() 获取本机所有 IP
• 选择 IP 匹配的 GID
• 更直接但需要额外系统调用

为什么选择方式一

• 与内核子系统对齐，使用与标准工具相同的数据源
• 更通用，不受 IP 配置变化影响
• 实现简单，改动最小
• 性能更好，只需一次文件读取

请求 Review
请帮忙看看这个方案是否有问题，或者有更好的解决方式？

[gemini-code-assist]

Summary of Changes

Hello @uniqueni, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

此拉取请求旨在修复一个错误（issue 946），通过改进 RDMA 上下文中最佳 GID 索引的选择机制来提高系统的鲁棒性。核心改动是引入了一种从系统文件读取网络设备信息的方法，以确保所选的 GID 索引与一个活跃且可用的网络接口相关联，从而避免潜在的连接问题。

Highlights

• 新增辅助函数 readGidNdev: 引入了一个新的静态辅助函数 readGidNdev，用于从 /sys/class/infiniband 文件系统路径读取与给定 GID 索引关联的网络设备名称。
• 优化 getBestGidIndex 逻辑: 修改了 RdmaContext::getBestGidIndex 函数，使其在选择最佳 GID 索引时，优先选择那些具有实际网络设备关联的 GID。如果找到符合类型要求且关联了网络设备的 GID，则立即返回；否则，将符合类型要求但无网络设备关联的 GID 作为备选，并继续查找。

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[gemini-code-assist]

Code Review

你好，这个 PR 通过读取 sysfs 来检查 GID 是否关联了网络设备，从而改进了 getBestGidIndex 的逻辑，优先选择有网络接口的 GID。这是一个合理的修复方向。我发现一个小问题，即在没有 GID 关联网络设备时的回退逻辑发生了变化，可能会从选择“第一个”符合条件的 GID 变为“最后一个”。我在代码中留下了具体的建议，希望能帮助你完善这个修复。

[Copilot]

Pull Request Overview

This PR fixes a bug in getBestGidIndex() where the function would select the first matching GID (IPv4-mapped + RoCE v2 or IB type) without verifying if it belongs to a local network interface. The fix ensures that GIDs associated with actual network devices are preferred.

Key changes:

• Added readGidNdev() helper function to read network device information from sysfs
• Modified getBestGidIndex() to prioritize GIDs with associated network devices
• Implemented fallback logic to retain original behavior when no network device is found

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[alogfans]

Looks good, will merge after fixing building problems

[uniqueni]

Looks good, will merge after fixing building problems

thank you！ It's fixed

[ShangmingCai]

@uniqueni please fix format, thank you.