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Date: Sun, 14 Sep 2025 11:47:17 +0800
From: Tzung-Bi Shih <tzungbi@kernel.org>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Benson Leung <bleung@chromium.org>
Cc: linux-input@vger.kernel.org, chrome-platform@lists.linux.dev
Subject: Re: [PATCH 0/5] platform/chrome: Fix a race when probing drivers
Message-ID: <aMY6xeh-RSiaWDc5@tzungbi-laptop>
References: <20250828083601.856083-1-tzungbi@kernel.org>
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In-Reply-To: <20250828083601.856083-1-tzungbi@kernel.org>

On Thu, Aug 28, 2025 at 08:35:56AM +0000, Tzung-Bi Shih wrote:
> A race is observed when cros_ec_lpc and cros-ec-keyb are all built as
> modules.  cros_ec_lpc is cros-ec-keyb's parent.  However, they can be
> probed at the same time.
> 
> Example:
> 
> + -----------------------------------------------------------------+
> | Some init process (e.g. udevd) | deferred_probe_work_func worker |
> + -----------------------------------------------------------------+
> | Probe cros-ec-keyb.            |                                 |
> | - Decide to defer[1].          |                                 |
> |                                | A device bound to a driver[2].  |
> | Probe cros_ec_lpc.             |                                 |
> | - Init the struct[3].          |                                 |
> |                                | Retry cros-ec-keyb from the     |
> |                                | deferred list[4].               |
> |                                | - Won't defer again as [3].     |
> |                                | - Access uninitialized data in  |
> |                                |   the struct.                   |
> | - Register the device.         |                                 |
> + -----------------------------------------------------------------+

> [...]

Applied to

    https://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux.git for-next

[1/5] platform/chrome: Centralize cros_ec_device allocation
      commit: 918856986014142271a70a334d300994b9c41720
[2/5] platform/chrome: Centralize common cros_ec_device initialization
      commit: e19ceeb1c0f63e3e15b197c5f34797134b51ba0e
[3/5] platform/chrome: cros_ec: Separate initialization from cros_ec_register()
      commit: 7a79b0bfd8b3995a39d25bffcf57273635c0e542
[4/5] platform/chrome: cros_ec: Add a flag to track registration state
      commit: 56cb557279d70397cefb497e0f06bdd6fd685f8e
[5/5] Input: cros_ec_keyb - Defer probe until parent EC device is registered
      commit: 48633acccf38d706d7b368400647bb9db9caf1ae

Thanks!