greybus: fix uart request_operation()

This fixes a problem similar to what was found in the battery
protcool driver code.

There's no need to allocate a local buffer, that already set up
by gb_operation_create().  Just use that instead.

Change a few variable names to reflect that they hold response
messages, not request messages.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

diff --git a/drivers/staging/greybus/uart-gb.c b/drivers/staging/greybus/uart-gb.c
index a8c342eb09d3c9fc135f15256540c86ea9879b89..d01956acdedca2b20d0ae473b8e0e23c70de8ba0 100644 (file)
--- a/drivers/staging/greybus/uart-gb.c
+++ b/drivers/staging/greybus/uart-gb.c
@@ -144,19 +144,12 @@ static int request_operation(struct gb_connection *connection, int type,
                             void *response, int response_size)
 {
        struct gb_operation *operation;
-       struct gb_uart_simple_response *fake_request;
-       u8 *local_response;
+       struct gb_uart_simple_response *fake_response;
        int ret;
 
-       local_response = kmalloc(response_size, GFP_KERNEL);
-       if (!local_response)
-               return -ENOMEM;
-
        operation = gb_operation_create(connection, type, 0, response_size);
-       if (!operation) {
-               kfree(local_response);
+       if (!operation)
                return -ENOMEM;
-       }
 
        /* Synchronous operation--no callback */
        ret = gb_operation_request_send(operation, NULL);
@@ -170,19 +163,18 @@ static int request_operation(struct gb_connection *connection, int type,
         * layout for where the status is, so cast this to a random request so
         * we can see the status easier.
         */
-       fake_request = (struct gb_uart_simple_response *)local_response;
-       if (fake_request->status) {
+       fake_response = operation->response.payload;
+       if (fake_response->status) {
                gb_connection_err(connection, "response %hhu",
-                       fake_request->status);
+                       fake_response->status);
                ret = -EIO;
        } else {
                /* Good request, so copy to the caller's buffer */
                if (response_size && response)
-                       memcpy(response, local_response, response_size);
+                       memcpy(response, fake_response, response_size);
        }
 out:
        gb_operation_destroy(operation);
-       kfree(local_response);
 
        return ret;
 }
@@ -193,23 +185,23 @@ out:
  */
 static int get_version(struct gb_tty *tty)
 {
-       struct gb_uart_proto_version_response version_request;
+       struct gb_uart_proto_version_response version_response;
        int retval;
 
        retval = request_operation(tty->connection,
                                   GB_UART_REQ_PROTOCOL_VERSION,
-                                  &version_request, sizeof(version_request));
+                                  &version_response, sizeof(version_response));
        if (retval)
                return retval;
 
-       if (version_request.major > GB_UART_VERSION_MAJOR) {
+       if (version_response.major > GB_UART_VERSION_MAJOR) {
                pr_err("unsupported major version (%hhu > %hhu)\n",
-                       version_request.major, GB_UART_VERSION_MAJOR);
+                       version_response.major, GB_UART_VERSION_MAJOR);
                return -ENOTSUPP;
        }
 
-       tty->version_major = version_request.major;
-       tty->version_minor = version_request.minor;
+       tty->version_major = version_response.major;
+       tty->version_minor = version_response.minor;
        return 0;
 }