From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [janitor] remove casts in drivers/net/arm/ Date: Tue, 02 Mar 2004 14:07:36 -0500 Sender: netdev-bounce@oss.sgi.com Message-ID: <4044DB78.7040309@pobox.com> References: <20040229142516.3d218ed0.rddunlap@osdl.org> <20040229143436.4bb884ee.rddunlap@osdl.org> <20040302121042.A9931@flint.arm.linux.org.uk> <4044D86C.70709@pobox.com> <20040302110237.0f580736.rddunlap@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: rmk@arm.linux.org.uk, netdev@oss.sgi.com Return-path: To: "Randy.Dunlap" In-Reply-To: <20040302110237.0f580736.rddunlap@osdl.org> Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Randy.Dunlap wrote: > On Tue, 02 Mar 2004 13:54:36 -0500 Jeff Garzik wrote: > > | Russell King wrote: > | > On Sun, Feb 29, 2004 at 02:34:36PM -0800, Randy.Dunlap wrote: > | > > | >> drivers/net/arm/am79c961a.c | 18 +++++++++--------- > | >> drivers/net/arm/ether1.c | 18 +++++++++--------- > | >> drivers/net/arm/ether3.c | 18 +++++++++--------- > | >> drivers/net/arm/etherh.c | 4 ++-- > | >> 4 files changed, 29 insertions(+), 29 deletions(-) > | > > | > > | > I think we should really consider using netdev_priv() in all these places > | > so the compiler knows that 'dev' and 'priv' are related. > | > | > | Good point. > > I respectfully disagree, but if the maintainter won't merge > them as is, so be it. > > I have trouble understanding why this: > return (char *)dev + ((sizeof(struct net_device) + 31) & ~31); > is better than using a structure->field, i.e., > dev->priv > > Can one of you enlighten me? One is an additional pointer load and dereference, and one is a constant offset from the beginning of the dev structure, calculated at compile time. netdev_priv() provides the same results as dev->priv but at less cost. Jeff