usb: typec: ucsi: Rework ppm_lock handling

The ppm_lock really only needs to be hold during 2 functions:
ucsi_reset_ppm() and ucsi_run_command().

Push the taking of the lock down into these 2 functions, renaming
ucsi_run_command() to ucsi_send_command() which was an existing
wrapper already taking the lock for its callers.

This simplifies things for the callers and removes the difference
between ucsi_send_command() and ucsi_run_command() which has led
to various locking bugs in the past.

Cc: stable@vger.kernel.org
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/20200809141904.4317-4-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index 3b208ea59a5032cdd57645e7521e2c84b3273f13..8a35144211e5f638a3f98c9715bb4772b80fb3f5 100644 (file)
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -146,42 +146,33 @@ static int ucsi_exec_command(struct ucsi *ucsi, u64 cmd)
        return UCSI_CCI_LENGTH(cci);
 }
 
-static int ucsi_run_command(struct ucsi *ucsi, u64 command,
-                           void *data, size_t size)
+int ucsi_send_command(struct ucsi *ucsi, u64 command,
+                     void *data, size_t size)
 {
        u8 length;
        int ret;
 
-       WARN_ON(!mutex_is_locked(&ucsi->ppm_lock));
+       mutex_lock(&ucsi->ppm_lock);
 
        ret = ucsi_exec_command(ucsi, command);
        if (ret < 0)
-               return ret;
+               goto out;
 
        length = ret;
 
        if (data) {
                ret = ucsi->ops->read(ucsi, UCSI_MESSAGE_IN, data, size);
                if (ret)
-                       return ret;
+                       goto out;
        }
 
        ret = ucsi_acknowledge_command(ucsi);
        if (ret)
-               return ret;
-
-       return length;
-}
+               goto out;
 
-int ucsi_send_command(struct ucsi *ucsi, u64 command,
-                     void *retval, size_t size)
-{
-       int ret;
-
-       mutex_lock(&ucsi->ppm_lock);
-       ret = ucsi_run_command(ucsi, command, retval, size);
+       ret = length;
+out:
        mutex_unlock(&ucsi->ppm_lock);
-
        return ret;
 }
 EXPORT_SYMBOL_GPL(ucsi_send_command);
@@ -738,20 +729,24 @@ static int ucsi_reset_ppm(struct ucsi *ucsi)
        u32 cci;
        int ret;
 
+       mutex_lock(&ucsi->ppm_lock);
+
        ret = ucsi->ops->async_write(ucsi, UCSI_CONTROL, &command,
                                     sizeof(command));
        if (ret < 0)
-               return ret;
+               goto out;
 
        tmo = jiffies + msecs_to_jiffies(UCSI_TIMEOUT_MS);
 
        do {
-               if (time_is_before_jiffies(tmo))
-                       return -ETIMEDOUT;
+               if (time_is_before_jiffies(tmo)) {
+                       ret = -ETIMEDOUT;
+                       goto out;
+               }
 
                ret = ucsi->ops->read(ucsi, UCSI_CCI, &cci, sizeof(cci));
                if (ret)
-                       return ret;
+                       goto out;
 
                /* If the PPM is still doing something else, reset it again. */
                if (cci & ~UCSI_CCI_RESET_COMPLETE) {
@@ -759,13 +754,15 @@ static int ucsi_reset_ppm(struct ucsi *ucsi)
                                                     &command,
                                                     sizeof(command));
                        if (ret < 0)
-                               return ret;
+                               goto out;
                }
 
                msleep(20);
        } while (!(cci & UCSI_CCI_RESET_COMPLETE));
 
-       return 0;
+out:
+       mutex_unlock(&ucsi->ppm_lock);
+       return ret;
 }
 
 static int ucsi_role_cmd(struct ucsi_connector *con, u64 command)
@@ -777,9 +774,7 @@ static int ucsi_role_cmd(struct ucsi_connector *con, u64 command)
                u64 c;
 
                /* PPM most likely stopped responding. Resetting everything. */
-               mutex_lock(&con->ucsi->ppm_lock);
                ucsi_reset_ppm(con->ucsi);
-               mutex_unlock(&con->ucsi->ppm_lock);
 
                c = UCSI_SET_NOTIFICATION_ENABLE | con->ucsi->ntfy;
                ucsi_send_command(con->ucsi, c, NULL, 0);
@@ -1010,8 +1005,6 @@ static int ucsi_init(struct ucsi *ucsi)
        int ret;
        int i;
 
-       mutex_lock(&ucsi->ppm_lock);
-
        /* Reset the PPM */
        ret = ucsi_reset_ppm(ucsi);
        if (ret) {
@@ -1022,13 +1015,13 @@ static int ucsi_init(struct ucsi *ucsi)
        /* Enable basic notifications */
        ucsi->ntfy = UCSI_ENABLE_NTFY_CMD_COMPLETE | UCSI_ENABLE_NTFY_ERROR;
        command = UCSI_SET_NOTIFICATION_ENABLE | ucsi->ntfy;
-       ret = ucsi_run_command(ucsi, command, NULL, 0);
+       ret = ucsi_send_command(ucsi, command, NULL, 0);
        if (ret < 0)
                goto err_reset;
 
        /* Get PPM capabilities */
        command = UCSI_GET_CAPABILITY;
-       ret = ucsi_run_command(ucsi, command, &ucsi->cap, sizeof(ucsi->cap));
+       ret = ucsi_send_command(ucsi, command, &ucsi->cap, sizeof(ucsi->cap));
        if (ret < 0)
                goto err_reset;
 
@@ -1045,8 +1038,6 @@ static int ucsi_init(struct ucsi *ucsi)
                goto err_reset;
        }
 
-       mutex_unlock(&ucsi->ppm_lock);
-
        /* Register all connectors */
        for (i = 0; i < ucsi->cap.num_connectors; i++) {
                ret = ucsi_register_port(ucsi, i);
@@ -1072,12 +1063,9 @@ err_unregister:
                con->port = NULL;
        }
 
-       mutex_lock(&ucsi->ppm_lock);
 err_reset:
        ucsi_reset_ppm(ucsi);
 err:
-       mutex_unlock(&ucsi->ppm_lock);
-
        return ret;
 }