* [PATCH] usb: typec: ucsi: split connector lock classes
@ 2026-05-15 6:00 Sergey Senozhatsky
2026-05-18 12:21 ` Heikki Krogerus
0 siblings, 1 reply; 2+ messages in thread
From: Sergey Senozhatsky @ 2026-05-15 6:00 UTC (permalink / raw)
To: Heikki Krogerus
Cc: Greg Kroah-Hartman, linux-usb, linux-kernel, Sergey Senozhatsky
Lockdep detects a possible recursive locking scenario during
ucsi init:
[ 5.418616] ============================================
[ 5.418634] WARNING: possible recursive locking detected
[ 5.418706] --------------------------------------------
[ 5.418725] kworker/4:1/82 is trying to acquire lock:
[ 5.418759] ffff888119a34648 (&con->lock){+.+.}-{3:3}, at: ucsi_init_work+0x1a78/0x2eb0 [typec_ucsi]
[ 5.418801]
but task is already holding lock:
[ 5.418835] ffff888119a34080 (&con->lock){+.+.}-{3:3}, at: ucsi_init_work+0x1a78/0x2eb0 [typec_ucsi]
[ 5.418884]
other info that might help us debug this:
[ 5.418904] Possible unsafe locking scenario:
[ 5.418937] CPU0
[ 5.418956] ----
[ 5.418991] lock(&con->lock);
[ 5.419013] lock(&con->lock);
[ 5.419033]
*** DEADLOCK ***
[ 5.419387] Call Trace:
[ 5.419406] <TASK>
[ 5.419425] dump_stack_lvl+0x61/0xa0
[ 5.419448] print_deadlock_bug+0x4a6/0x650
[ 5.419483] __lock_acquire+0x62b6/0x7f50
[ 5.419507] lock_acquire+0x11b/0x390
[ 5.419654] __mutex_lock+0xbc/0xcd0
[ 5.419741] ucsi_init_work+0x1a78/0x2eb0
[ 5.419785] ? worker_thread+0xf53/0x2bc0
[ 5.419819] worker_thread+0xff4/0x2bc0
[ 5.419842] kthread+0x2a7/0x330
[ 5.419863] ? __pfx_worker_thread+0x10/0x10
[ 5.419896] ? __pfx_kthread+0x10/0x10
[ 5.419916] ret_from_fork+0x38/0x70
[ 5.419936] ? __pfx_kthread+0x10/0x10
[ 5.419969] ret_from_fork_asm+0x1b/0x30
[ 5.419991] </TASK>
[ 5.420009] ---[ end trace 0000000000000000 ]---
The problem is that all connector locks belong to the same
lockdep lock class, so the following loop:
for (i = 0; i < ucsi->cap.num_connectors; i++)
ucsi_register_port(connector[i])
mutex_lock(&connector[i]->lock)
looks like a recursive acquire of the same mutex. Put each connector
lock into a dedicated lock class so that lockdep doesn't see it as a
possible recursion.
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
drivers/usb/typec/ucsi/ucsi.c | 8 ++++++++
drivers/usb/typec/ucsi/ucsi.h | 1 +
2 files changed, 9 insertions(+)
diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index 5b7ad9e99cb9..43da7512dea0 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -1642,6 +1642,7 @@ static int ucsi_register_port(struct ucsi *ucsi, struct ucsi_connector *con)
INIT_WORK(&con->work, ucsi_handle_connector_change);
init_completion(&con->complete);
mutex_init(&con->lock);
+ lockdep_set_class(&con->lock, &con->lock_key);
INIT_LIST_HEAD(&con->partner_tasks);
con->ucsi = ucsi;
@@ -1887,6 +1888,9 @@ static int ucsi_init(struct ucsi *ucsi)
goto err_reset;
}
+ for (i = 0; i < ucsi->cap.num_connectors; i++)
+ lockdep_register_key(&connector[i].lock_key);
+
/* Register all connectors */
for (i = 0; i < ucsi->cap.num_connectors; i++) {
connector[i].num = i + 1;
@@ -1916,6 +1920,9 @@ static int ucsi_init(struct ucsi *ucsi)
return 0;
err_unregister:
+ for (i = 0; i < ucsi->cap.num_connectors; i++)
+ lockdep_unregister_key(&connector[i].lock_key);
+
for (con = connector; con->port; con++) {
if (con->wq)
destroy_workqueue(con->wq);
@@ -2166,6 +2173,7 @@ void ucsi_unregister(struct ucsi *ucsi)
usb_power_delivery_unregister(ucsi->connector[i].pd);
ucsi->connector[i].pd = NULL;
typec_unregister_port(ucsi->connector[i].port);
+ lockdep_unregister_key(&ucsi->connector[i].lock_key);
}
kfree(ucsi->connector);
diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
index cff9ddc2ae21..51f6c3c0d365 100644
--- a/drivers/usb/typec/ucsi/ucsi.h
+++ b/drivers/usb/typec/ucsi/ucsi.h
@@ -517,6 +517,7 @@ struct ucsi_connector {
struct ucsi *ucsi;
struct mutex lock; /* port lock */
+ struct lock_class_key lock_key;
struct work_struct work;
struct completion complete;
struct workqueue_struct *wq;
--
2.54.0.563.g4f69b47b94-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] usb: typec: ucsi: split connector lock classes
2026-05-15 6:00 [PATCH] usb: typec: ucsi: split connector lock classes Sergey Senozhatsky
@ 2026-05-18 12:21 ` Heikki Krogerus
0 siblings, 0 replies; 2+ messages in thread
From: Heikki Krogerus @ 2026-05-18 12:21 UTC (permalink / raw)
To: Sergey Senozhatsky; +Cc: Greg Kroah-Hartman, linux-usb, linux-kernel
On Fri, May 15, 2026 at 03:00:30PM +0900, Sergey Senozhatsky wrote:
> Lockdep detects a possible recursive locking scenario during
> ucsi init:
>
> [ 5.418616] ============================================
> [ 5.418634] WARNING: possible recursive locking detected
> [ 5.418706] --------------------------------------------
> [ 5.418725] kworker/4:1/82 is trying to acquire lock:
> [ 5.418759] ffff888119a34648 (&con->lock){+.+.}-{3:3}, at: ucsi_init_work+0x1a78/0x2eb0 [typec_ucsi]
> [ 5.418801]
> but task is already holding lock:
> [ 5.418835] ffff888119a34080 (&con->lock){+.+.}-{3:3}, at: ucsi_init_work+0x1a78/0x2eb0 [typec_ucsi]
> [ 5.418884]
> other info that might help us debug this:
> [ 5.418904] Possible unsafe locking scenario:
>
> [ 5.418937] CPU0
> [ 5.418956] ----
> [ 5.418991] lock(&con->lock);
> [ 5.419013] lock(&con->lock);
> [ 5.419033]
> *** DEADLOCK ***
>
> [ 5.419387] Call Trace:
> [ 5.419406] <TASK>
> [ 5.419425] dump_stack_lvl+0x61/0xa0
> [ 5.419448] print_deadlock_bug+0x4a6/0x650
> [ 5.419483] __lock_acquire+0x62b6/0x7f50
> [ 5.419507] lock_acquire+0x11b/0x390
> [ 5.419654] __mutex_lock+0xbc/0xcd0
> [ 5.419741] ucsi_init_work+0x1a78/0x2eb0
> [ 5.419785] ? worker_thread+0xf53/0x2bc0
> [ 5.419819] worker_thread+0xff4/0x2bc0
> [ 5.419842] kthread+0x2a7/0x330
> [ 5.419863] ? __pfx_worker_thread+0x10/0x10
> [ 5.419896] ? __pfx_kthread+0x10/0x10
> [ 5.419916] ret_from_fork+0x38/0x70
> [ 5.419936] ? __pfx_kthread+0x10/0x10
> [ 5.419969] ret_from_fork_asm+0x1b/0x30
> [ 5.419991] </TASK>
> [ 5.420009] ---[ end trace 0000000000000000 ]---
>
> The problem is that all connector locks belong to the same
> lockdep lock class, so the following loop:
>
> for (i = 0; i < ucsi->cap.num_connectors; i++)
> ucsi_register_port(connector[i])
> mutex_lock(&connector[i]->lock)
>
> looks like a recursive acquire of the same mutex. Put each connector
> lock into a dedicated lock class so that lockdep doesn't see it as a
> possible recursion.
>
> Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> ---
> drivers/usb/typec/ucsi/ucsi.c | 8 ++++++++
> drivers/usb/typec/ucsi/ucsi.h | 1 +
> 2 files changed, 9 insertions(+)
>
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index 5b7ad9e99cb9..43da7512dea0 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -1642,6 +1642,7 @@ static int ucsi_register_port(struct ucsi *ucsi, struct ucsi_connector *con)
> INIT_WORK(&con->work, ucsi_handle_connector_change);
> init_completion(&con->complete);
> mutex_init(&con->lock);
> + lockdep_set_class(&con->lock, &con->lock_key);
> INIT_LIST_HEAD(&con->partner_tasks);
> con->ucsi = ucsi;
>
> @@ -1887,6 +1888,9 @@ static int ucsi_init(struct ucsi *ucsi)
> goto err_reset;
> }
>
> + for (i = 0; i < ucsi->cap.num_connectors; i++)
> + lockdep_register_key(&connector[i].lock_key);
> +
> /* Register all connectors */
> for (i = 0; i < ucsi->cap.num_connectors; i++) {
> connector[i].num = i + 1;
> @@ -1916,6 +1920,9 @@ static int ucsi_init(struct ucsi *ucsi)
> return 0;
>
> err_unregister:
> + for (i = 0; i < ucsi->cap.num_connectors; i++)
> + lockdep_unregister_key(&connector[i].lock_key);
> +
> for (con = connector; con->port; con++) {
> if (con->wq)
> destroy_workqueue(con->wq);
> @@ -2166,6 +2173,7 @@ void ucsi_unregister(struct ucsi *ucsi)
> usb_power_delivery_unregister(ucsi->connector[i].pd);
> ucsi->connector[i].pd = NULL;
> typec_unregister_port(ucsi->connector[i].port);
> + lockdep_unregister_key(&ucsi->connector[i].lock_key);
> }
>
> kfree(ucsi->connector);
> diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
> index cff9ddc2ae21..51f6c3c0d365 100644
> --- a/drivers/usb/typec/ucsi/ucsi.h
> +++ b/drivers/usb/typec/ucsi/ucsi.h
> @@ -517,6 +517,7 @@ struct ucsi_connector {
>
> struct ucsi *ucsi;
> struct mutex lock; /* port lock */
> + struct lock_class_key lock_key;
> struct work_struct work;
> struct completion complete;
> struct workqueue_struct *wq;
> --
> 2.54.0.563.g4f69b47b94-goog
--
heikki
^ permalink raw reply [flat|nested] 2+ messages in thread
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