Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964953AbbDPJqG (ORCPT ); Thu, 16 Apr 2015 05:46:06 -0400 Received: from gloria.sntech.de ([95.129.55.99]:55835 "EHLO gloria.sntech.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753443AbbDPJpz (ORCPT ); Thu, 16 Apr 2015 05:45:55 -0400 From: Heiko =?ISO-8859-1?Q?St=FCbner?= To: Javier Martinez Canillas Cc: Olof Johansson , Lee Jones , Doug Anderson , Bill Richardson , Simon Glass , Gwendal Grignou , Stephen Barber , Filipe Brandenburger , Todd Broch , linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RESEND PATCH 4/8] mfd: cros_ec: Use a zero-length array for command data Date: Thu, 16 Apr 2015 11:45:42 +0200 Message-ID: <3714344.xf4aIv3C10@diego> User-Agent: KMail/4.14.1 (Linux/3.16.0-4-amd64; KDE/4.14.2; x86_64; ; ) In-Reply-To: <1428336906-14906-5-git-send-email-javier.martinez@collabora.co.uk> References: <1428336906-14906-1-git-send-email-javier.martinez@collabora.co.uk> <1428336906-14906-5-git-send-email-javier.martinez@collabora.co.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1908 Lines: 46 Am Montag, 6. April 2015, 18:15:02 schrieb Javier Martinez Canillas: > Commit 1b84f2a4cd4a ("mfd: cros_ec: Use fixed size arrays to transfer > data with the EC") modified the struct cros_ec_command fields to not > use pointers for the input and output buffers and use fixed length > arrays instead. > > This change was made because the cros_ec ioctl API uses that struct > cros_ec_command to allow user-space to send commands to the EC and > to get data from the EC. So using pointers made the API not 64-bit > safe. Unfortunately this approach was not flexible enough for all > the use-cases since there may be a need to send larger commands > on newer versions of the EC command protocol. > > So to avoid to choose a constant length that it may be too big for > most commands and thus wasting memory and CPU cycles on copy from > and to user-space or having a size that is too small for some big > commands, use a zero-length array that is both 64-bit safe and > flexible. The same buffer is used for both output and input data > so the maximum of these values should be used to allocate it. > > Suggested-by: Gwendal Grignou > Signed-off-by: Javier Martinez Canillas > --- [...] > /* Module initialization */ > @@ -269,3 +301,4 @@ void ec_dev_sysfs_remove(struct cros_ec_device *ec) > { > sysfs_remove_group(&ec->vdev->kobj, &ec_attr_group); > } > + .git/rebase-apply/patch:893: new blank line at EOF. > diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h > index 14cf522123dd..7eee38abd02a 100644 > --- a/include/linux/mfd/cros_ec.h > +++ b/include/linux/mfd/cros_ec.h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/