From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754536AbaIWHuZ (ORCPT ); Tue, 23 Sep 2014 03:50:25 -0400 Received: from mail-lb0-f174.google.com ([209.85.217.174]:37961 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753705AbaIWHuX (ORCPT ); Tue, 23 Sep 2014 03:50:23 -0400 X-Google-Original-Sender: Date: Tue, 23 Sep 2014 09:47:49 +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: <20140923074749.GO5237@localhost> References: <1411414759-7056-1-git-send-email-octavian.purdila@intel.com> <1411414759-7056-2-git-send-email-octavian.purdila@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1411414759-7056-2-git-send-email-octavian.purdila@intel.com> 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 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 Reviewed-by: Johan Hovold > --- > 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; > + } > + > mutex_init(&vb->lock); > > vb->usb_dev = usb_get_dev(interface_to_usbdev(interface)); > @@ -105,6 +111,7 @@ static int vprbrd_probe(struct usb_interface *interface, > error: > if (vb) { > usb_put_dev(vb->usb_dev); > + kfree(vb->buf); > kfree(vb); > } > > @@ -118,6 +125,7 @@ static void vprbrd_disconnect(struct usb_interface *interface) > mfd_remove_devices(&interface->dev); > usb_set_intfdata(interface, NULL); > usb_put_dev(vb->usb_dev); > + kfree(vb->buf); > kfree(vb); > > dev_dbg(&interface->dev, "disconnected\n"); > diff --git a/include/linux/mfd/viperboard.h b/include/linux/mfd/viperboard.h > index 1934528..af928d0 100644 > --- a/include/linux/mfd/viperboard.h > +++ b/include/linux/mfd/viperboard.h > @@ -103,7 +103,7 @@ struct vprbrd_i2c_addr_msg { > struct vprbrd { > struct usb_device *usb_dev; /* the usb device for this device */ > struct mutex lock; > - u8 buf[sizeof(struct vprbrd_i2c_write_msg)]; > + u8 *buf; > struct platform_device pdev; > };