[sexenteen]

拉取/合并请求描述：(PR description)

[

为什么提交这份PR (why to submit this PR)

Fixes #7813.

echo xxx /dev/uart0 makes the console stop responding afterwards.

The issue attributes this to rt_serial_open() overwriting dev->open_flag, but on current
master that is no longer the triggering path:

• rt_device_open() (components/drivers/core/device.c) already skips the driver open()
  when the OFLAG_MASK bits match, so for this second open rt_serial_open() is not called
  at all and open_flag is not clobbered.
• The actual cause is serial_fops_close(): it unconditionally clears rx_indicate while the
  device is still held by the console (ref_count only goes 3 -> 2, so rt_device_close()
  does not close the driver). rx_indicate is what wakes readers
  (serial_fops_rx_ind() -> rt_wqueue_wakeup(POLLIN)), so the console never receives input
  again.

Runtime trace taken with temporary rt_kprintf (removed before this commit), on
bsp/qemu-vexpress-a9:

fops_open  ENTER: ref_count=2 open_flag=0x014b
fops_open  EXIT : ret=0 open_flag=0x014b ref_count=3   <- rt_serial_open NOT called
fops_close ENTER: ref_count=3 rx_indicate=0x6005afa0
fops_close EXIT : ref_count=2 rx_indicate=0x00000000   <- callback dropped

This is also why #7814 (dev->open_flag |= oflag & 0xff;) did not fix the problem: the
overwrite it targets does not happen in this scenario.

你的解决方案是什么 (what is your solution)

Drop the rx indication callback only when the device is really released, mirroring the rule
the device layer itself already uses for device_close():

rt_device_close(device);
if (device->ref_count == 0)
{
    rt_device_set_rx_indicate(device, RT_NULL);
}

Only serial_fops_close() is touched (+9/-1). rt_serial_open() is intentionally left alone:
its dev->open_flag = oflag & 0xff; can still drop flag bits in other configuration
combinations, but that is the separate topic discussed in #7814 and is kept out of this PR.

请提供验证的bsp和config (provide the config and bsp)

• BSP: bsp/qemu-vexpress-a9
• .config: default configuration (RT_USING_SERIAL_V1, console on uart0)
• action: https://github.com/sexenteen/rt-thread/actions/runs/40216938843

Verification (the commands were sent one by one with a delay, so the RX FIFO is not overflowed;
sending them all at once produces misleading truncation):

before the change:

msh />echo hello /dev/uart0
hellomsh />free
(no output for `free` or `version` afterwards -- the console is dead)

after the change:

msh />echo hello /dev/uart0
hellomsh />free
total    : 66358504
used     : 29912
maximum  : 46448
available: 66328592
msh />version
(normal output)

Robustness: two consecutive echo ... /dev/uart0 calls followed by free and ps both keep
working.

Also checked:

• scons -j4 on bsp/qemu-vexpress-a9 passes
• tools/ci/clang_format_check.py reports "clang-format check success" for the changed lines

Not covered: real hardware, and other processes that hold the same port concurrently (they
should benefit from the same fix, but were not tested individually).

]

当前拉取/合并请求的状态 Intent for your PR

必须选择一项 Choose one (Mandatory):

• 本拉取/合并请求是一个草稿版本 This PR is for a code-review and is intended to get feedback
• 本拉取/合并请求是一个成熟版本 This PR is mature, and ready to be integrated into the repo

代码质量 Code Quality：

我在这个拉取/合并请求中已经考虑了 As part of this pull request, I've considered the following:

• 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
• 代码风格正确，包括缩进空格，命名及其他风格 Style guide is adhered to, including spacing, naming and other styles
• 没有垃圾代码，代码尽量精简，不包含#if 0代码，不包含已经被注释了的代码 All redundant code is removed and cleaned up
• 所有变更均有原因及合理的，并且不会影响到其他软件组件代码或BSP All modifications are justified and not affect other components or BSP
• 对难懂代码均提供对应的注释 I've commented appropriately where code is tricky
• 代码是高质量的 Code in this PR is of high quality
• 已经使用clang-format 源码格式化工具确保格式符合RT-Thread代码规范 This PR has been formatted with clang-format and complies with RT-Thread code specification
• 如果是新增bsp, 已经添加ci检查到.github/ALL_BSP_COMPILE.json 详细请参考链接BSP自查

[github-actions]

👋 感谢您对 RT-Thread 的贡献！Thank you for your contribution to RT-Thread!

为确保代码符合 RT-Thread 的编码规范，请在你的仓库中执行以下步骤运行代码格式化工作流（如果格式化CI运行失败）。
To ensure your code complies with RT-Thread's coding style, please run the code formatting workflow by following the steps below (If the formatting of CI fails to run).

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完成后，提交将自动更新至 fix/issue-7813-serial-fops-rx-indicate 分支，关联的 Pull Request 也会同步更新。
Once completed, commits will be pushed to the fix/issue-7813-serial-fops-rx-indicate branch automatically, and the related Pull Request will be updated.

如有问题欢迎联系我们，再次感谢您的贡献！💐
If you have any questions, feel free to reach out. Thanks again for your contribution!

[github-actions]

📌 Code Review Assignment

🏷️ Tag: components

Reviewers: @Maihuanyi

Changed Files (Click to expand)

• components/drivers/serial/dev_serial.c

---

📊 Current Review Status (Last Updated: 2026-10-26 01:32 CST)

• ⌛ @Maihuanyi Pending Review

---

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   Comment LGTM/lgtm after confirming approval

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[CYFS3]

LGTM