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>

1 files changed, 72 insertions, 0 deletions

diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index 9802c5930c10..e825f013e54e 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -586,6 +586,77 @@ out:
 }
 
 /**
+ * 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
  *
  * @fd: file descriptor
@@ -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
 };