greybus: connection: make connection enable/disable thread safe

Add connection mutex to protect connection enabling and disabling.

This is needed to eventually allow drivers to manage the state of their
connections during operation (i.e. post probe and pre disconnect).

Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/connection.c b/drivers/staging/greybus/connection.c
index 0159fbd..56588f3 100644 (file)
--- a/drivers/staging/greybus/connection.c
+++ b/drivers/staging/greybus/connection.c
@@ -170,6 +170,7 @@ gb_connection_create(struct gb_host_device *hd, int hd_cport_id,
        connection->state = GB_CONNECTION_STATE_DISABLED;
 
        atomic_set(&connection->op_cycle, 0);
+       mutex_init(&connection->mutex);
        spin_lock_init(&connection->lock);
        INIT_LIST_HEAD(&connection->operations);
 
@@ -390,9 +391,14 @@ int gb_connection_enable(struct gb_connection *connection,
 {
        int ret;
 
+       mutex_lock(&connection->mutex);
+
+       if (connection->state == GB_CONNECTION_STATE_ENABLED)
+               goto out_unlock;
+
        ret = gb_connection_hd_cport_enable(connection);
        if (ret)
-               return ret;
+               goto err_unlock;
 
        ret = gb_connection_svc_connection_create(connection);
        if (ret)
@@ -407,6 +413,9 @@ int gb_connection_enable(struct gb_connection *connection,
        if (ret)
                goto err_svc_destroy;
 
+out_unlock:
+       mutex_unlock(&connection->mutex);
+
        return 0;
 
 err_svc_destroy:
@@ -418,6 +427,8 @@ err_svc_destroy:
        gb_connection_svc_connection_destroy(connection);
 err_hd_cport_disable:
        gb_connection_hd_cport_disable(connection);
+err_unlock:
+       mutex_unlock(&connection->mutex);
 
        return ret;
 }
@@ -425,8 +436,10 @@ EXPORT_SYMBOL_GPL(gb_connection_enable);
 
 void gb_connection_disable(struct gb_connection *connection)
 {
+       mutex_lock(&connection->mutex);
+
        if (connection->state == GB_CONNECTION_STATE_DISABLED)
-               return;
+               goto out_unlock;
 
        gb_connection_control_disconnected(connection);
 
@@ -437,6 +450,9 @@ void gb_connection_disable(struct gb_connection *connection)
 
        gb_connection_svc_connection_destroy(connection);
        gb_connection_hd_cport_disable(connection);
+
+out_unlock:
+       mutex_unlock(&connection->mutex);
 }
 EXPORT_SYMBOL_GPL(gb_connection_disable);
 

diff --git a/drivers/staging/greybus/connection.h b/drivers/staging/greybus/connection.h
index b774b9c..e7c6feb 100644 (file)
--- a/drivers/staging/greybus/connection.h
+++ b/drivers/staging/greybus/connection.h
@@ -43,6 +43,7 @@ struct gb_connection {
        u8                              module_major;
        u8                              module_minor;
 
+       struct mutex                    mutex;
        spinlock_t                      lock;
        enum gb_connection_state        state;
        struct list_head                operations;