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Tue, 29 Sep 2026 06:46:42 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-885e24eb8e4sm959867b3a.50.2026.09.29.06.46.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Sep 2026 06:46:41 -0700 (PDT) Sender: Guenter Roeck From: Guenter Roeck To: linux-watchdog@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Guenter Roeck Subject: [PATCH 3/8] watchdog: core: Prevent ping worker from re-arming timer on suspend Date: Tue, 29 Sep 2026 06:46:30 -0700 Message-ID: <20260929134635.2567137-4-linux@roeck-us.net> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20260929134635.2567137-1-linux@roeck-us.net> References: <20260929134635.2567137-1-linux@roeck-us.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- drivers/watchdog/watchdog_core.h | 1 + drivers/watchdog/watchdog_dev.c | 15 +++++++++++---- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/watchdog/watchdog_core.h b/drivers/watchdog/watchdog_core.h index ab825d9f9248..c6df5a584357 100644 --- a/drivers/watchdog/watchdog_core.h +++ b/drivers/watchdog/watchdog_core.h @@ -60,6 +60,7 @@ struct watchdog_core_data { #define _WDOG_DEV_OPEN 0 /* Opened ? */ #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */ #define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */ +#define _WDOG_SUSPENDED 3 /* Suspended ? */ }; /* diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index 50224877ff49..e38f1ef8e683 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -81,6 +81,9 @@ static inline bool watchdog_need_worker(struct watchdog_device *wdd) unsigned int hm = wdd->max_hw_heartbeat_ms; unsigned int t = wdd->timeout * 1000; + if (test_bit(_WDOG_SUSPENDED, &wdd->wd_data->status)) + return false; + /* * A worker to generate heartbeat requests is needed if all of the * following conditions are true. @@ -154,9 +157,10 @@ static int __watchdog_ping(struct watchdog_device *wdd) now = ktime_get(); if (ktime_after(earliest_keepalive, now)) { - hrtimer_start(&wd_data->timer, - ktime_sub(earliest_keepalive, now), - HRTIMER_MODE_REL_HARD); + if (!test_bit(_WDOG_SUSPENDED, &wd_data->status)) + hrtimer_start(&wd_data->timer, + ktime_sub(earliest_keepalive, now), + HRTIMER_MODE_REL_HARD); return 0; } @@ -207,7 +211,7 @@ static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data) { struct watchdog_device *wdd = wd_data->wdd; - if (!wdd) + if (!wdd || test_bit(_WDOG_SUSPENDED, &wd_data->status)) return false; if (watchdog_active(wdd)) @@ -1318,6 +1322,8 @@ int watchdog_dev_suspend(struct watchdog_device *wdd) mutex_lock(&wd_data->lock); if (watchdog_worker_should_ping(wd_data)) ret = __watchdog_ping(wd_data->wdd); + if (!ret) + set_bit(_WDOG_SUSPENDED, &wd_data->status); mutex_unlock(&wd_data->lock); if (ret) @@ -1346,6 +1352,7 @@ int watchdog_dev_resume(struct watchdog_device *wdd) * ping worker if needed. */ mutex_lock(&wd_data->lock); + clear_bit(_WDOG_SUSPENDED, &wd_data->status); if (watchdog_worker_should_ping(wd_data)) ret = __watchdog_ping(wd_data->wdd); mutex_unlock(&wd_data->lock); -- 2.45.2