mei: fix ssize_t to int assignment in read and write ops.

Use ssize_t for rets variables in mei_write(), mei_read(), and
mei_cl_write() as well as change the return type of mei_cl_write()
to ssize_t, to prevent assignment of possible 64bit size_t
to int 32 bit variable.

As by product also eliminate warning
drivers/misc/mei/client.c:1702:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/client.c

@@ -1644,13 +1644,13 @@ int mei_cl_irq_write(struct mei_cl *cl, struct mei_cl_cb *cb,
  *
  * Return: number of bytes sent on success, <0 on failure.
  */
-int mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb)
+ssize_t mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb)
 {
 	struct mei_device *dev;
 	struct mei_msg_data *buf;
 	struct mei_msg_hdr mei_hdr;
-	int size;
-	int rets;
+	size_t len;
+	ssize_t rets;
 	bool blocking;
 
 	if (WARN_ON(!cl || !cl->dev))
@@ -1662,15 +1662,15 @@ int mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb)
 	dev = cl->dev;
 
 	buf = &cb->buf;
-	size = buf->size;
+	len = buf->size;
 	blocking = cb->blocking;
 
-	cl_dbg(dev, cl, "size=%d\n", size);
+	cl_dbg(dev, cl, "len=%zd\n", len);
 
 	rets = pm_runtime_get(dev->dev);
 	if (rets < 0 && rets != -EINPROGRESS) {
 		pm_runtime_put_noidle(dev->dev);
-		cl_err(dev, cl, "rpm: get failed %d\n", rets);
+		cl_err(dev, cl, "rpm: get failed %zd\n", rets);
 		goto free;
 	}
 
@@ -1689,21 +1689,21 @@ int mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb)
 
 	if (rets == 0) {
 		cl_dbg(dev, cl, "No flow control credentials: not sending.\n");
-		rets = size;
+		rets = len;
 		goto out;
 	}
 	if (!mei_hbuf_acquire(dev)) {
 		cl_dbg(dev, cl, "Cannot acquire the host buffer: not sending.\n");
-		rets = size;
+		rets = len;
 		goto out;
 	}
 
 	/* Check for a maximum length */
-	if (size > mei_hbuf_max_len(dev)) {
+	if (len > mei_hbuf_max_len(dev)) {
 		mei_hdr.length = mei_hbuf_max_len(dev);
 		mei_hdr.msg_complete = 0;
 	} else {
-		mei_hdr.length = size;
+		mei_hdr.length = len;
 		mei_hdr.msg_complete = 1;
 	}
 
@@ -1745,7 +1745,7 @@ int mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb)
 		}
 	}
 
-	rets = size;
+	rets = len;
 err:
 	cl_dbg(dev, cl, "rpm: autosuspend\n");
 	pm_runtime_mark_last_busy(dev->dev);

drivers/misc/mei/client.h

@@ -202,7 +202,7 @@ int mei_cl_connect(struct mei_cl *cl, struct mei_me_client *me_cl,
 int mei_cl_irq_connect(struct mei_cl *cl, struct mei_cl_cb *cb,
 		       struct list_head *cmpl_list);
 int mei_cl_read_start(struct mei_cl *cl, size_t length, const struct file *fp);
-int mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb);
+ssize_t mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb);
 int mei_cl_irq_write(struct mei_cl *cl, struct mei_cl_cb *cb,
 		     struct list_head *cmpl_list);
 

drivers/misc/mei/main.c

@@ -137,7 +137,7 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
 	struct mei_device *dev;
 	struct mei_cl_cb *cb = NULL;
 	bool nonblock = !!(file->f_flags & O_NONBLOCK);
-	int rets;
+	ssize_t rets;
 
 	if (WARN_ON(!cl || !cl->dev))
 		return -ENODEV;
@@ -170,7 +170,7 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
 
 	rets = mei_cl_read_start(cl, length, file);
 	if (rets && rets != -EBUSY) {
-		cl_dbg(dev, cl, "mei start read failure status = %d\n", rets);
+		cl_dbg(dev, cl, "mei start read failure status = %zd\n", rets);
 		goto out;
 	}
 
@@ -204,7 +204,7 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
 	/* now copy the data to user space */
 	if (cb->status) {
 		rets = cb->status;
-		cl_dbg(dev, cl, "read operation failed %d\n", rets);
+		cl_dbg(dev, cl, "read operation failed %zd\n", rets);
 		goto free;
 	}
 
@@ -236,7 +236,7 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
 	*offset = 0;
 
 out:
-	cl_dbg(dev, cl, "end mei read rets = %d\n", rets);
+	cl_dbg(dev, cl, "end mei read rets = %zd\n", rets);
 	mutex_unlock(&dev->device_lock);
 	return rets;
 }
@@ -256,7 +256,7 @@ static ssize_t mei_write(struct file *file, const char __user *ubuf,
 	struct mei_cl *cl = file->private_data;
 	struct mei_cl_cb *cb;
 	struct mei_device *dev;
-	int rets;
+	ssize_t rets;
 
 	if (WARN_ON(!cl || !cl->dev))
 		return -ENODEV;