linux-kernel - [PATCH] usb: typec: ucsi: Fix workqueue destruction race during connector cleanup

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Message-ID: <20251002013026.4095030-1-acelan.kao@canonical.com>
Date: Thu,  2 Oct 2025 09:30:26 +0800
From: "Chia-Lin Kao (AceLan)" <acelan.kao@...onical.com>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
	Andrei Kuchynski <akuchynski@...omium.org>,
	Łukasz Bartosik <ukaszb@...omium.org>,
	Venkat Jayaraman <venkat.jayaraman@...el.com>,
	"Chia-Lin Kao (AceLan)" <acelan.kao@...onical.com>,
	linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] usb: typec: ucsi: Fix workqueue destruction race during connector cleanup

During UCSI initialization and operation, there is a race condition where
delayed work items can be scheduled but attempt to queue work after the
workqueue has been destroyed. This occurs in multiple code paths.

The race occurs when:
1. ucsi_partner_task() or ucsi_poll_worker() schedule delayed work
2. Connector cleanup paths call destroy_workqueue()
3. Previously scheduled delayed work timers fire after destruction
4. This triggers warnings and crashes in __queue_work()

The issue is timing-sensitive and typically manifests when:
- Port registration fails due to PPM timing issues
- System shutdown/cleanup occurs with pending delayed work
- Module removal races with active delayed work

Fix this by:
1. Creating ucsi_destroy_connector_wq() helper function that safely
   cancels all pending delayed work before destroying workqueues
2. Applying the safe cleanup to all three workqueue destruction paths:
   - ucsi_register_port() error path
   - ucsi_init() error path
   - ucsi_unregister() cleanup path

This prevents both the initial queueing on destroyed workqueues and
retry attempts from running workers, eliminating the timer races.

Fixes: b9aa02ca39a4 ("usb: typec: ucsi: Add polling mechanism for partner tasks like alt mode checking")
Cc: stable@...r.kernel.org
Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao@...onical.com>
---
 drivers/usb/typec/ucsi/ucsi.c | 50 ++++++++++++++++++++++-------------
 1 file changed, 31 insertions(+), 19 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index 5ba3a6c81964..1f71c9983163 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -283,6 +283,33 @@ static void ucsi_poll_worker(struct work_struct *work)
 	mutex_unlock(&con->lock);
 }
 
+/**
+ * ucsi_destroy_connector_wq - Safely destroy connector workqueue
+ * @con: UCSI connector
+ *
+ * Cancel all pending delayed work and destroy the workqueue to prevent
+ * timer races where delayed work tries to queue on destroyed workqueue.
+ */
+static void ucsi_destroy_connector_wq(struct ucsi_connector *con)
+{
+	struct ucsi_work *uwork, *tmp;
+
+	if (!con->wq)
+		return;
+
+	/* Cancel any pending delayed work before destroying workqueue */
+	mutex_lock(&con->lock);
+	list_for_each_entry_safe(uwork, tmp, &con->partner_tasks, node) {
+		cancel_delayed_work_sync(&uwork->work);
+		list_del(&uwork->node);
+		kfree(uwork);
+	}
+	mutex_unlock(&con->lock);
+
+	destroy_workqueue(con->wq);
+	con->wq = NULL;
+}
+
 static int ucsi_partner_task(struct ucsi_connector *con,
 			     int (*cb)(struct ucsi_connector *),
 			     int retries, unsigned long delay)
@@ -1798,10 +1825,8 @@ static int ucsi_register_port(struct ucsi *ucsi, struct ucsi_connector *con)
 out_unlock:
 	mutex_unlock(&con->lock);
 
-	if (ret && con->wq) {
-		destroy_workqueue(con->wq);
-		con->wq = NULL;
-	}
+	if (ret)
+		ucsi_destroy_connector_wq(con);
 
 	return ret;
 }
@@ -1921,8 +1946,7 @@ static int ucsi_init(struct ucsi *ucsi)
 
 err_unregister:
 	for (con = connector; con->port; con++) {
-		if (con->wq)
-			destroy_workqueue(con->wq);
+		ucsi_destroy_connector_wq(con);
 		ucsi_unregister_partner(con);
 		ucsi_unregister_altmodes(con, UCSI_RECIPIENT_CON);
 		ucsi_unregister_port_psy(con);
@@ -2144,19 +2168,7 @@ void ucsi_unregister(struct ucsi *ucsi)
 	for (i = 0; i < ucsi->cap.num_connectors; i++) {
 		cancel_work_sync(&ucsi->connector[i].work);
 
-		if (ucsi->connector[i].wq) {
-			struct ucsi_work *uwork;
-
-			mutex_lock(&ucsi->connector[i].lock);
-			/*
-			 * queue delayed items immediately so they can execute
-			 * and free themselves before the wq is destroyed
-			 */
-			list_for_each_entry(uwork, &ucsi->connector[i].partner_tasks, node)
-				mod_delayed_work(ucsi->connector[i].wq, &uwork->work, 0);
-			mutex_unlock(&ucsi->connector[i].lock);
-			destroy_workqueue(ucsi->connector[i].wq);
-		}
+		ucsi_destroy_connector_wq(&ucsi->connector[i]);
 
 		ucsi_unregister_partner(&ucsi->connector[i]);
 		ucsi_unregister_altmodes(&ucsi->connector[i],
-- 
2.43.0