Add timeout for write_serial_console_log function.

[Zhidong Peng (ZhidongPeng)]

In some Linux VM, our GPA VMExtension detects the GPA status are stale and our log from syslog indicates our GPA service may hang at write_serial_console_log.

Jul 30 19:53:11 4ld30d3vm azure-proxy-agent[1725592]: The log folder is not set, skip write to GPA managed file log.
Jul 30 19:53:12 4ld30d3vm azure-proxy-agent[1725592]: ============== GuestProxyAgent (1.0.48) is starting on Linux:Ubuntu-22.4.0(x86_64), elapsed: 498

Side changes to have reliable CI action results, pin the rust version for linux_lint and windows_lint. We will upgrade the rust version in a separate PR.

[Copilot]

Pull request overview

This PR hardens Linux startup/provision logging by making write_serial_console_log non-blocking with a bounded timeout to prevent hangs observed on some Linux VMs, and updates call sites accordingly. It also attempts to make CI results more reliable by pinning Rust for lint jobs and making cargo-audit installs deterministic.

Changes:

• Add a non-blocking serial console write helper with a 2s timeout and unit tests (proxy_agent/src/common/logger.rs).
• Update Linux-only call sites to the new write_serial_console_log(message, path_override) signature (service.rs, provision.rs, helpers.rs).
• Update CI lint jobs to use a pinned Rust toolchain and cargo install --locked for cargo-audit (.github/workflows/ci.yml).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
proxy_agent/src/service.rs	Updates Linux startup serial-console logging call to new signature.
proxy_agent/src/provision.rs	Updates provision-state serial-console logging calls to new signature.
proxy_agent/src/common/logger.rs	Implements non-blocking /dev/console writes with timeout + adds unit tests.
proxy_agent/src/common/helpers.rs	Updates startup event logging call to new signature.
.github/workflows/ci.yml	Attempts to pin Rust for lint jobs and adds --locked for cargo-audit installation.

Suppressed comments (1)

.github/workflows/ci.yml:44

• Same as linux_lint: dtolnay/rust-toolchain@1.95.0 is an action ref and does not pin the Rust compiler version. Use the action’s toolchain input to pin Rust, and keep the action itself on a stable tag (or SHA).

      - uses: dtolnay/rust-toolchain@1.95.0
        with:
          components: rustfmt clippy

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