struct fw_cdev_queue_iso request;
        struct fw_cdev_iso_packet __user *p, *end, *next;
        struct fw_iso_context *ctx = client->iso_context;
-       unsigned long payload, payload_end, header_length;
+       unsigned long payload, buffer_end, header_length;
        int count;
        struct {
                struct fw_iso_packet packet;
         * and the request.data pointer is ignored.*/
 
        payload = (unsigned long)request.data - client->vm_start;
-       payload_end = payload + (client->buffer.page_count << PAGE_SHIFT);
+       buffer_end = client->buffer.page_count << PAGE_SHIFT;
        if (request.data == 0 || client->buffer.pages == NULL ||
-           payload >= payload_end) {
+           payload >= buffer_end) {
                payload = 0;
-               payload_end = 0;
+               buffer_end = 0;
        }
 
        if (!access_ok(VERIFY_READ, request.packets, request.size))
                if (u.packet.skip && ctx->type == FW_ISO_CONTEXT_TRANSMIT &&
                    u.packet.header_length + u.packet.payload_length > 0)
                        return -EINVAL;
-               if (payload + u.packet.payload_length > payload_end)
+               if (payload + u.packet.payload_length > buffer_end)
                        return -EINVAL;
 
                if (fw_iso_context_queue(ctx, &u.packet,