From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754124AbaIWHlP (ORCPT ); Tue, 23 Sep 2014 03:41:15 -0400 Received: from mail-lb0-f169.google.com ([209.85.217.169]:48258 "EHLO mail-lb0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751559AbaIWHlO (ORCPT ); Tue, 23 Sep 2014 03:41:14 -0400 X-Google-Original-Sender: Date: Tue, 23 Sep 2014 09:38:40 +0200 From: Johan Hovold To: Octavian Purdila Cc: sameo@linux.intel.com, lee.jones@linaro.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, johan@kernel.org Subject: Re: [PATCH v2 1/2] mfd: viperboard: allocate I/O buffer separately Message-ID: <20140923073840.GN5237@localhost> References: <1411414759-7056-1-git-send-email-octavian.purdila@intel.com> <1411414759-7056-2-git-send-email-octavian.purdila@intel.com> <20140923073541.GM5237@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140923073541.GM5237@localhost> User-Agent: Mutt/1.5.22 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 23, 2014 at 09:35:41AM +0200, Johan Hovold wrote: > On Mon, Sep 22, 2014 at 10:39:18PM +0300, Octavian Purdila wrote: > > Currently the I/O buffer is allocated part of the device status > > structure, potentially sharing the same cache line with other members > > in this structure. > > > > Allocate the buffer separately, to avoid the I/O operations corrupting > > the device status structure due to cache line sharing. > > > > Compiled tested only as I don't have access to hardware. > > > > Signed-off-by: Octavian Purdila > > --- > > drivers/mfd/viperboard.c | 8 ++++++++ > > include/linux/mfd/viperboard.h | 2 +- > > 2 files changed, 9 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c > > index e00f534..5f62f4e 100644 > > --- a/drivers/mfd/viperboard.c > > +++ b/drivers/mfd/viperboard.c > > @@ -64,6 +64,12 @@ static int vprbrd_probe(struct usb_interface *interface, > > return -ENOMEM; > > } > > > > + vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL); > > + if (vb->buf == NULL) { > > + ret = -ENOMEM; > > + goto error; > > This will cause a kref imbalance as you have a usb_put_dev in error, > but haven't done the get yet. Nevermind. This isn't problem as the usb device is null. Haven't had my morning coffee yet. ;) Johan