mei: implement fsync

When write() returns successfully, it is only assumed that a message
was successfully queued. Add fsync syscall implementation to help
user-space ensure that all data is written.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index 9802c5930c101ae7be2f851da6343f98d942cfcd..e825f013e54e42ff171f1c93e776770fbfb3b1d1 100644 (file)
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -585,6 +585,77 @@ static unsigned int mei_poll(struct file *file, poll_table *wait)
        return mask;
 }
 
+/**
+ * mei_cl_is_write_queued - check if the client has pending writes.
+ *
+ * @cl: writing host client
+ *
+ * Return: true if client is writing, false otherwise.
+ */
+static bool mei_cl_is_write_queued(struct mei_cl *cl)
+{
+       struct mei_device *dev = cl->dev;
+       struct mei_cl_cb *cb;
+
+       list_for_each_entry(cb, &dev->write_list, list)
+               if (cb->cl == cl)
+                       return true;
+       list_for_each_entry(cb, &dev->write_waiting_list, list)
+               if (cb->cl == cl)
+                       return true;
+       return false;
+}
+
+/**
+ * mei_fsync - the fsync handler
+ *
+ * @fp:       pointer to file structure
+ * @start:    unused
+ * @end:      unused
+ * @datasync: unused
+ *
+ * Return: 0 on success, -ENODEV if client is not connected
+ */
+static int mei_fsync(struct file *fp, loff_t start, loff_t end, int datasync)
+{
+       struct mei_cl *cl = fp->private_data;
+       struct mei_device *dev;
+       int rets;
+
+       if (WARN_ON(!cl || !cl->dev))
+               return -ENODEV;
+
+       dev = cl->dev;
+
+       mutex_lock(&dev->device_lock);
+
+       if (dev->dev_state != MEI_DEV_ENABLED || !mei_cl_is_connected(cl)) {
+               rets = -ENODEV;
+               goto out;
+       }
+
+       while (mei_cl_is_write_queued(cl)) {
+               mutex_unlock(&dev->device_lock);
+               rets = wait_event_interruptible(cl->tx_wait,
+                               cl->writing_state == MEI_WRITE_COMPLETE ||
+                               !mei_cl_is_connected(cl));
+               mutex_lock(&dev->device_lock);
+               if (rets) {
+                       if (signal_pending(current))
+                               rets = -EINTR;
+                       goto out;
+               }
+               if (!mei_cl_is_connected(cl)) {
+                       rets = -ENODEV;
+                       goto out;
+               }
+       }
+       rets = 0;
+out:
+       mutex_unlock(&dev->device_lock);
+       return rets;
+}
+
 /**
  * mei_fasync - asynchronous io support
  *
@@ -700,6 +771,7 @@ static const struct file_operations mei_fops = {
        .release = mei_release,
        .write = mei_write,
        .poll = mei_poll,
+       .fsync = mei_fsync,
        .fasync = mei_fasync,
        .llseek = no_llseek
 };