[PATCH v2 2/2] platform/chrome: cros_ec_typec: Add lock per-port

[Radu Vele <raduvele@google.com>]

Add a lock associated to each port to protect port data against
concurrent access. Concurrency may result from sysfs commands
and ec events.

Signed-off-by: Radu Vele <raduvele@google.com>

---
  Changes in v2:
    - Followed Tzung-Bi's suggestion to use the guard mechanism for
      managing mutexes. This also removes the declaration of `ret`
      in the middle of the function that Benson pointed out.
---
 drivers/platform/chrome/cros_ec_typec.c | 10 ++++++++++
 drivers/platform/chrome/cros_ec_typec.h |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
index e689bfaf95dc..f6a3d73a967f 100644
--- a/drivers/platform/chrome/cros_ec_typec.c
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -7,7 +7,9 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/cleanup.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/platform_data/cros_ec_commands.h>
 #include <linux/platform_data/cros_usbpd_notify.h>
@@ -54,6 +56,7 @@ static int cros_typec_enter_usb_mode(struct typec_port *tc_port, enum usb_mode m
 		.mode_to_enter = CROS_EC_ALTMODE_USB4
 	};
 
+	guard(mutex)(&port->lock);
 	return cros_ec_cmd(port->typec_data->ec, 0, EC_CMD_TYPEC_CONTROL,
 			  &req, sizeof(req), NULL, 0);
 }
@@ -70,6 +73,8 @@ static int cros_typec_perform_role_swap(struct typec_port *tc_port, int target_r
 	if (!data->pd_ctrl_ver)
 		return -EOPNOTSUPP;
 
+	guard(mutex)(&port->lock);
+
 	/* First query the state */
 	req.port = port->port_num;
 	req.role = USB_PD_CTRL_ROLE_NO_CHANGE;
@@ -378,6 +383,7 @@ static void cros_unregister_ports(struct cros_typec_data *typec)
 		if (!typec->ports[i])
 			continue;
 
+		mutex_lock(&typec->ports[i]->lock);
 		cros_typec_remove_partner(typec, i);
 		cros_typec_remove_cable(typec, i);
 
@@ -386,6 +392,8 @@ static void cros_unregister_ports(struct cros_typec_data *typec)
 		typec_mux_put(typec->ports[i]->mux);
 		cros_typec_unregister_port_altmodes(typec->ports[i]);
 		typec_unregister_port(typec->ports[i]->port);
+		mutex_unlock(&typec->ports[i]->lock);
+		mutex_destroy(&typec->ports[i]->lock);
 	}
 }
 
@@ -480,6 +488,7 @@ static int cros_typec_init_ports(struct cros_typec_data *typec)
 			goto unregister_ports;
 		}
 
+		mutex_init(&cros_port->lock);
 		cros_port->port_num = port_num;
 		cros_port->typec_data = typec;
 		typec->ports[port_num] = cros_port;
@@ -1240,6 +1249,7 @@ static int cros_typec_port_update(struct cros_typec_data *typec, int port_num)
 		return -EINVAL;
 	}
 
+	guard(mutex)(&typec->ports[port_num]->lock);
 	req.port = port_num;
 	req.role = USB_PD_CTRL_ROLE_NO_CHANGE;
 	req.mux = USB_PD_CTRL_MUX_NO_CHANGE;
diff --git a/drivers/platform/chrome/cros_ec_typec.h b/drivers/platform/chrome/cros_ec_typec.h
index f9c31f04c102..d0a8a12ec91a 100644
--- a/drivers/platform/chrome/cros_ec_typec.h
+++ b/drivers/platform/chrome/cros_ec_typec.h
@@ -82,6 +82,9 @@ struct cros_typec_port {
 	struct usb_power_delivery_capabilities *partner_sink_caps;
 
 	struct cros_typec_data *typec_data;
+
+	/* Mutex to protect port data against concurrent access */
+	struct mutex lock;
 };
 
 #endif /*  __CROS_EC_TYPEC__ */
-- 
2.50.0.727.gbf7dc18ff4-goog