Commit 364618c8 authored by Andrei Kuchynski's avatar Andrei Kuchynski Committed by Greg Kroah-Hartman
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usb: typec: ucsi: displayport: Fix deadlock 



This patch introduces the ucsi_con_mutex_lock / ucsi_con_mutex_unlock
functions to the UCSI driver. ucsi_con_mutex_lock ensures the connector
mutex is only locked if a connection is established and the partner pointer
is valid. This resolves a deadlock scenario where
ucsi_displayport_remove_partner holds con->mutex waiting for
dp_altmode_work to complete while dp_altmode_work attempts to acquire it.

Cc: stable <stable@kernel.org>
Fixes: af8622f6 ("usb: typec: ucsi: Support for DisplayPort alt mode")
Signed-off-by: default avatarAndrei Kuchynski <akuchynski@chromium.org>
Reviewed-by: default avatarHeikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20250424084429.3220757-2-akuchynski@chromium.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9f657a92

drivers/usb/typec/ucsi/displayport.c

+11 −8
Original line number Diff line number Diff line
@@ -54,7 +54,8 @@ static int ucsi_displayport_enter(struct typec_altmode *alt, u32 *vdo) 
	u8 cur = 0;

	int ret;



	mutex_lock(&dp->con->lock);

	if (!ucsi_con_mutex_lock(dp->con))

		return -ENOTCONN;



	if (!dp->override && dp->initialized) {

		const struct typec_altmode *p = typec_altmode_get_partner(alt);
@@ -100,7 +101,7 @@ static int ucsi_displayport_enter(struct typec_altmode *alt, u32 *vdo) 
	schedule_work(&dp->work);

	ret = 0;

err_unlock:

	mutex_unlock(&dp->con->lock);

	ucsi_con_mutex_unlock(dp->con);



	return ret;

}
@@ -112,7 +113,8 @@ static int ucsi_displayport_exit(struct typec_altmode *alt) 
	u64 command;

	int ret = 0;



	mutex_lock(&dp->con->lock);

	if (!ucsi_con_mutex_lock(dp->con))

		return -ENOTCONN;



	if (!dp->override) {

		const struct typec_altmode *p = typec_altmode_get_partner(alt);
@@ -144,7 +146,7 @@ static int ucsi_displayport_exit(struct typec_altmode *alt) 
	schedule_work(&dp->work);



out_unlock:

	mutex_unlock(&dp->con->lock);

	ucsi_con_mutex_unlock(dp->con);



	return ret;

}
@@ -202,20 +204,21 @@ static int ucsi_displayport_vdm(struct typec_altmode *alt, 
	int cmd = PD_VDO_CMD(header);

	int svdm_version;



	mutex_lock(&dp->con->lock);

	if (!ucsi_con_mutex_lock(dp->con))

		return -ENOTCONN;



	if (!dp->override && dp->initialized) {

		const struct typec_altmode *p = typec_altmode_get_partner(alt);



		dev_warn(&p->dev,

			 "firmware doesn't support alternate mode overriding\n");

		mutex_unlock(&dp->con->lock);

		ucsi_con_mutex_unlock(dp->con);

		return -EOPNOTSUPP;

	}



	svdm_version = typec_altmode_get_svdm_version(alt);

	if (svdm_version < 0) {

		mutex_unlock(&dp->con->lock);

		ucsi_con_mutex_unlock(dp->con);

		return svdm_version;

	}
@@ -259,7 +262,7 @@ static int ucsi_displayport_vdm(struct typec_altmode *alt, 
		break;

	}



	mutex_unlock(&dp->con->lock);

	ucsi_con_mutex_unlock(dp->con);



	return 0;

}

drivers/usb/typec/ucsi/ucsi.c

+34 −0
Original line number Diff line number Diff line
@@ -1922,6 +1922,40 @@ void ucsi_set_drvdata(struct ucsi *ucsi, void *data) 
}

EXPORT_SYMBOL_GPL(ucsi_set_drvdata);



/**

 * ucsi_con_mutex_lock - Acquire the connector mutex

 * @con: The connector interface to lock

 *

 * Returns true on success, false if the connector is disconnected

 */

bool ucsi_con_mutex_lock(struct ucsi_connector *con)

{

	bool mutex_locked = false;

	bool connected = true;



	while (connected && !mutex_locked) {

		mutex_locked = mutex_trylock(&con->lock) != 0;

		connected = UCSI_CONSTAT(con, CONNECTED);

		if (connected && !mutex_locked)

			msleep(20);

	}



	connected = connected && con->partner;

	if (!connected && mutex_locked)

		mutex_unlock(&con->lock);



	return connected;

}



/**

 * ucsi_con_mutex_unlock - Release the connector mutex

 * @con: The connector interface to unlock

 */

void ucsi_con_mutex_unlock(struct ucsi_connector *con)

{

	mutex_unlock(&con->lock);

}



/**

 * ucsi_create - Allocate UCSI instance

 * @dev: Device interface to the PPM (Platform Policy Manager)

drivers/usb/typec/ucsi/ucsi.h

+2 −0
Original line number Diff line number Diff line
@@ -94,6 +94,8 @@ int ucsi_register(struct ucsi *ucsi); 
void ucsi_unregister(struct ucsi *ucsi);

void *ucsi_get_drvdata(struct ucsi *ucsi);

void ucsi_set_drvdata(struct ucsi *ucsi, void *data);

bool ucsi_con_mutex_lock(struct ucsi_connector *con);

void ucsi_con_mutex_unlock(struct ucsi_connector *con);



void ucsi_connector_change(struct ucsi *ucsi, u8 num);