Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932589Ab0KRVeI (ORCPT ); Thu, 18 Nov 2010 16:34:08 -0500 Received: from swampdragon.chaosbits.net ([90.184.90.115]:12407 "EHLO swampdragon.chaosbits.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757165Ab0KRVeH (ORCPT ); Thu, 18 Nov 2010 16:34:07 -0500 Date: Thu, 18 Nov 2010 22:21:24 +0100 (CET) From: Jesper Juhl To: Linus Torvalds cc: linux-scsi@vger.kernel.org, "James E.J. Bottomley" , linux-kernel@vger.kernel.org, Eric Youngdale , "David S. Miller" , Mike Anderson , Russell King , Andrew Morton Subject: Re: [PATCH][resend][SCSI] Reduce number of sequential pointer derefs in scsi_error.c and reduce size as well In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 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: 2242 Lines: 54 On Thu, 18 Nov 2010, Linus Torvalds wrote: > On Thu, Nov 18, 2010 at 12:49 PM, Jesper Juhl wrote: > > > > Fair enough. Seeing your version of this and looking a second time at mine > > I have to agree completely. > > You are absolutely right in stating that the compiler will handle this > > just fine, so it's only a readabillity issue and your version is a *lot* > > more readable than what I came up with. > > Btw, one thing to look out for is all those function calls: it really > looks like many of them would be better off not having to dereference > the thing inside each helper function, but just have it dereferenced > in the caller. > > You might trying passing in "struct Scsi_Host *host" to a lot of those > helper functions in addition to the 'scmd' part. There's a lot of > "scmd->device->host" going on, and even if you remove some of them > _within_ a function, if you really want to get rid of them you should > probably do one of them in the caller. > > That's why the queuecommand() function was changed to take > > struct Scsi_Host *h, struct scsi_cmnd * > > as its arguments, because that host is used so commonly. And passing > two arguments is usually free (ie almost all architectures pass it in > registers), and that host variable almost always already exists in the > caller because the caller already needed it. > > So if you changed the functions that only take "scsi_cmnd *" as an > argument to match the new queuecommand() interface, I bet you'd get > more cleanups. And the interfaces would match. > That's a good point. I don't have time to look at that tonight, but I'll (hopefully) get around to it over the weekend. I'll submit a new patch (or at least email) during the weekend (or early next week) when I've had some time to look into that. Thanks. -- Jesper Juhl http://www.chaosbits.net/ Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html Plain text mails only, please. -- 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/