From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751860AbdEBJZi (ORCPT ); Tue, 2 May 2017 05:25:38 -0400 Received: from mail-lf0-f65.google.com ([209.85.215.65]:35895 "EHLO mail-lf0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750936AbdEBJZe (ORCPT ); Tue, 2 May 2017 05:25:34 -0400 Date: Tue, 2 May 2017 11:25:27 +0200 From: Johan Hovold To: Rob Herring Cc: Greg Kroah-Hartman , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Andrey Smirnov Subject: Re: [PATCH] tty: serdev: fix serdev_device_write return value Message-ID: <20170502092527.GC2973@localhost> References: <20170502001714.11576-1-robh@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170502001714.11576-1-robh@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 01, 2017 at 07:17:14PM -0500, Rob Herring wrote: > Commit 6fe729c4bdae ("serdev: Add serdev_device_write subroutine") > provides a compatibility wrapper for the existing > serdev_device_write_buf, but it fails to return the number of bytes > written causing users to timeout. So this would also be fixed for serdev_device_write_buf() by Stefan Wahren's patch restoring that function implementation, but returning the amount written is perhaps desirable also for blocking writes for consistency reasons. > Fixes: 6fe729c4bdae ("serdev: Add serdev_device_write subroutine") > Cc: Andrey Smirnov > Cc: Greg Kroah-Hartman > Signed-off-by: Rob Herring > --- > drivers/tty/serdev/core.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c > index 433de5ea9b02..ccfe56355c4f 100644 > --- a/drivers/tty/serdev/core.c > +++ b/drivers/tty/serdev/core.c > @@ -127,7 +127,7 @@ int serdev_device_write(struct serdev_device *serdev, > unsigned long timeout) > { > struct serdev_controller *ctrl = serdev->ctrl; > - int ret; > + int ret, wr_cnt = 0; > > if (!ctrl || !ctrl->ops->write_buf || > (timeout && !serdev->ops->write_wakeup)) > @@ -143,12 +143,13 @@ int serdev_device_write(struct serdev_device *serdev, > > buf += ret; > count -= ret; > + wr_cnt += ret; > > } while (count && > (timeout = wait_for_completion_timeout(&serdev->write_comp, > timeout))); > > mutex_unlock(&serdev->write_lock); > - return ret < 0 ? ret : (count ? -ETIMEDOUT : 0); > + return ret < 0 ? ret : (count ? -ETIMEDOUT : wr_cnt); That's some nasty use of the ternary operator. Ditching it completely would be more readable. if (ret < 0) return ret; if (count) return -ETIMEDOUT; return wr_count; and here wr_count is the value of count passed to the function (and could just be stored on entry instead). > } > EXPORT_SYMBOL_GPL(serdev_device_write); Thanks, Johan