From bed97b30968ba354035a020989df0623e52b5536 Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede@redhat.com>
Date: Sun, 9 Aug 2020 16:19:04 +0200
Subject: [PATCH] usb: typec: ucsi: Hold con->lock for the entire duration of
 ucsi_register_port()
Git-commit: bed97b30968ba354035a020989df0623e52b5536
References: git-fixes
Patch-mainline: v5.9-rc3

Commit 081da1325d35 ("usb: typec: ucsi: displayport: Fix a potential race
during registration") made the ucsi code hold con->lock in
ucsi_register_displayport(). But we really don't want any interactions
with the connector to run before the port-registration process is fully
complete.

This commit moves the taking of con->lock from ucsi_register_displayport()
into ucsi_register_port() to achieve this.

Cc: stable@vger.kernel.org
Fixes: 081da1325d35 ("usb: typec: ucsi: displayport: Fix a potential race during registration")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200809141904.4317-5-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/usb/typec/ucsi/displayport.c |    9 +--------
 drivers/usb/typec/ucsi/ucsi.c        |   29 +++++++++++++++++++++--------
 2 files changed, 22 insertions(+), 16 deletions(-)

--- a/drivers/usb/typec/ucsi/displayport.c
+++ b/drivers/usb/typec/ucsi/displayport.c
@@ -290,8 +290,6 @@ struct typec_altmode *ucsi_register_disp
 	struct typec_altmode *alt;
 	struct ucsi_dp *dp;
 
-	mutex_lock(&con->lock);
-
 	/* We can't rely on the firmware with the capabilities. */
 	desc->vdo |= DP_CAP_DP_SIGNALING | DP_CAP_RECEPTACLE;
 
@@ -300,15 +298,12 @@ struct typec_altmode *ucsi_register_disp
 	desc->vdo |= all_assignments << 16;
 
 	alt = typec_port_register_altmode(con->port, desc);
-	if (IS_ERR(alt)) {
-		mutex_unlock(&con->lock);
+	if (IS_ERR(alt))
 		return alt;
-	}
 
 	dp = devm_kzalloc(&alt->dev, sizeof(*dp), GFP_KERNEL);
 	if (!dp) {
 		typec_unregister_altmode(alt);
-		mutex_unlock(&con->lock);
 		return ERR_PTR(-ENOMEM);
 	}
 
@@ -321,7 +316,5 @@ struct typec_altmode *ucsi_register_disp
 	alt->ops = &ucsi_displayport_ops;
 	typec_altmode_set_drvdata(alt, dp);
 
-	mutex_unlock(&con->lock);
-
 	return alt;
 }
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -813,11 +813,14 @@ static int ucsi_register_port(struct ucs
 	con->num = index + 1;
 	con->ucsi = ucsi;
 
+	/* Delay other interactions with the con until registration is complete */
+	mutex_lock(&con->lock);
+
 	/* Get connector capability */
 	UCSI_CMD_GET_CONNECTOR_CAPABILITY(ctrl, con->num);
 	ret = ucsi_run_command(ucsi, &ctrl, &con->cap, sizeof(con->cap));
 	if (ret < 0)
-		return ret;
+		goto out;
 
 	if (con->cap.op_mode & UCSI_CONCAP_OPMODE_DRP)
 		cap->data = TYPEC_PORT_DRD;
@@ -848,22 +851,28 @@ static int ucsi_register_port(struct ucs
 
 	/* Register the connector */
 	con->port = typec_register_port(ucsi->dev, cap);
-	if (IS_ERR(con->port))
-		return PTR_ERR(con->port);
+	if (IS_ERR(con->port)) {
+		ret = PTR_ERR(con->port);
+		goto out;
+	}
 
 	/* Alternate modes */
 	ret = ucsi_register_altmodes(con, UCSI_RECIPIENT_CON);
-	if (ret)
+	if (ret) {
 		dev_err(ucsi->dev, "con%d: failed to register alt modes\n",
 			con->num);
+		goto out;
+	}
 
 	/* Get the status */
 	UCSI_CMD_GET_CONNECTOR_STATUS(ctrl, con->num);
 	ret = ucsi_run_command(ucsi, &ctrl, &con->status, sizeof(con->status));
 	if (ret < 0) {
 		dev_err(ucsi->dev, "con%d: failed to get status\n", con->num);
-		return 0;
+		ret = 0;
+		goto out;
 	}
+	ret = 0; /* ucsi_send_command() returns length on success */
 
 	ucsi_pwr_opmode_change(con);
 	typec_set_pwr_role(con->port, con->status.pwr_dir);
@@ -885,17 +894,21 @@ static int ucsi_register_port(struct ucs
 
 	if (con->partner) {
 		ret = ucsi_register_altmodes(con, UCSI_RECIPIENT_SOP);
-		if (ret)
+		if (ret) {
 			dev_err(ucsi->dev,
 				"con%d: failed to register alternate modes\n",
 				con->num);
-		else
+			ret = 0;
+		} else {
 			ucsi_altmode_update_active(con);
+		}
 	}
 
 	trace_ucsi_register_port(con->num, &con->status);
 
-	return 0;
+out:
+	mutex_unlock(&con->lock);
+	return ret;
 }
 
 static void ucsi_init(struct work_struct *work)