[PATCH 5.4 14/16] usb: typec: ucsi: displayport: Fix potential deadlock

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

5.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Heikki Krogerus <heikki.krogerus@linux.intel.com>

commit b791a67f68121d69108640d4a3e591d210ffe850 upstream.

The function ucsi_displayport_work() does not access the
connector, so it also must not acquire the connector lock.

This fixes a potential deadlock scenario:

ucsi_displayport_work() -> lock(&con->lock)
typec_altmode_vdm()
dp_altmode_vdm()
dp_altmode_work()
typec_altmode_enter()
ucsi_displayport_enter() -> lock(&con->lock)

Reported-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Fixes: af8622f6a585 ("usb: typec: ucsi: Support for DisplayPort alt mode")
Cc: stable@vger.kernel.org
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20240507134316.161999-1-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/typec/ucsi/displayport.c |    4 ----
 1 file changed, 4 deletions(-)

--- a/drivers/usb/typec/ucsi/displayport.c
+++ b/drivers/usb/typec/ucsi/displayport.c
@@ -251,8 +251,6 @@ static void ucsi_displayport_work(struct
 	struct ucsi_dp *dp = container_of(work, struct ucsi_dp, work);
 	int ret;
 
-	mutex_lock(&dp->con->lock);
-
 	ret = typec_altmode_vdm(dp->alt, dp->header,
 				dp->vdo_data, dp->vdo_size);
 	if (ret)
@@ -261,8 +259,6 @@ static void ucsi_displayport_work(struct
 	dp->vdo_data = NULL;
 	dp->vdo_size = 0;
 	dp->header = 0;
-
-	mutex_unlock(&dp->con->lock);
 }
 
 void ucsi_displayport_remove_partner(struct typec_altmode *alt)