From: Tzung-Bi Shih <tzungbi@kernel.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/8] watchdog: core: Prevent ping worker from re-arming timer on suspend
Date: Wed, 30 Sep 2026 19:53:49 +0800 [thread overview]
Message-ID: <arz4TZhOKTadhqx3@tzungbi-laptop> (raw)
In-Reply-To: <20260929134635.2567137-4-linux@roeck-us.net>
On Tue, Sep 29, 2026 at 06:46:30AM -0700, Guenter Roeck wrote:
> In watchdog_dev_suspend(), hrtimer_cancel() is called before
> kthread_cancel_work_sync(). If the timer expired just before
> hrtimer_cancel() and queued watchdog_ping_work(), the worker can run
> and acquire wd_data->lock while kthread_cancel_work_sync() waits for it
> to finish. Because no state flag indicates that the watchdog is
> suspended, watchdog_worker_should_ping() returns true and
> __watchdog_ping() re-arms wd_data->timer while the device is suspended.
>
> Add a _WDOG_SUSPENDED internal status bit to wd_data->status, set it
> under wd_data->lock in watchdog_dev_suspend(), clear it under
> wd_data->lock in watchdog_dev_resume(), and check it in
> watchdog_worker_should_ping(), watchdog_need_worker(), and
> __watchdog_ping() so the timer cannot be armed while suspended.
>
> Fixes: 60bcd91aafd2 ("watchdog: introduce watchdog_dev_suspend/resume")
> Assisted-by: LLM
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
next prev parent reply other threads:[~2026-09-30 11:53 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-29 13:46 [PATCH 0/8] watchdog: core: Fix locking, lifetime, suspend, and state management bugs Guenter Roeck
2026-09-29 13:46 ` [PATCH 1/8] watchdog: core: Clear wd_data pointer on errors Guenter Roeck
2026-09-30 11:53 ` Tzung-Bi Shih
2026-09-29 13:46 ` [PATCH 2/8] watchdog: core: Add missing locks Guenter Roeck
2026-09-30 11:53 ` Tzung-Bi Shih
2026-09-29 13:46 ` [PATCH 3/8] watchdog: core: Prevent ping worker from re-arming timer on suspend Guenter Roeck
2026-09-30 11:53 ` Tzung-Bi Shih [this message]
2026-09-29 13:46 ` [PATCH 4/8] watchdog: core: Stop pretimeout hrtimer " Guenter Roeck
2026-09-30 11:54 ` Tzung-Bi Shih
2026-09-29 13:46 ` [PATCH 5/8] watchdog: core: Restore WDOG_HW_RUNNING if stopping watchdog fails Guenter Roeck
2026-09-30 11:54 ` Tzung-Bi Shih
2026-09-30 12:37 ` Guenter Roeck
2026-09-29 13:46 ` [PATCH 6/8] watchdog: core: Cancel timer if cdev_device_add() fails Guenter Roeck
2026-09-30 11:54 ` Tzung-Bi Shih
2026-09-29 13:46 ` [PATCH 7/8] watchdog: core: Fix unbalanced module_put() in watchdog_open() Guenter Roeck
2026-09-30 11:54 ` Tzung-Bi Shih
2026-09-29 13:46 ` [PATCH 8/8] watchdog: core: Update last_keepalive in watchdog_start() Guenter Roeck
2026-09-30 11:54 ` Tzung-Bi Shih
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