From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753950Ab3BXRuA (ORCPT ); Sun, 24 Feb 2013 12:50:00 -0500 Received: from gloria.sntech.de ([95.129.55.99]:37328 "EHLO gloria.sntech.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751015Ab3BXRt6 (ORCPT ); Sun, 24 Feb 2013 12:49:58 -0500 From: Heiko =?iso-8859-15?q?St=FCbner?= To: Julia Lawall Subject: Re: question about arch/arm/mach-s3c24xx/irq.c Date: Sun, 24 Feb 2013 18:49:41 +0100 User-Agent: KMail/1.13.7 (Linux/3.2.0-3-686-pae; KDE/4.8.4; i686; ; ) Cc: "Russell King - ARM Linux" , ben-linux@fluff.org, kgene.kim@samsung.com, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org References: <201302241611.13028.heiko@sntech.de> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 8bit Message-Id: <201302241849.41638.heiko@sntech.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Sonntag, 24. Februar 2013, 16:45:18 schrieb Julia Lawall: > On Sun, 24 Feb 2013, Heiko Stübner wrote: > > Am Sonntag, 24. Februar 2013, 14:39:45 schrieb Julia Lawall: > > > [Adding the person who introduced the code] > > > > > > On Sun, 24 Feb 2013, Russell King - ARM Linux wrote: > > > > On Sun, Feb 24, 2013 at 12:45:11PM +0100, Julia Lawall wrote: > > > > > The function s3c24xx_irq_map in arch/arm/mach-s3c24xx/irq.c > > > > > contains the > > > > > > > > > > code: > > > > > parent_irq_data = > > > > > &parent_intc->irqs[irq_data->parent_irq]; > > > > > > > > > > if (!irq_data) { > > > > > > > > > > pr_err("irq-s3c24xx: no irq data found for > > > > > hwirq %lu\n", > > > > > > > > > > hw); > > > > > > > > > > goto err; > > > > > > > > > > } > > > > > > > > > > At this point irq_data has already been tested, so the null test on > > > > > irq_data does not look correct. But I wonder if parent_irq_data > > > > > could ever be null here? > > > > > > > > That would be really obscure - because that would require parent_intc > > > > to be a "negative" pointer (to counter-act the indexing by > > > > irq_data->parent_irq). So it looks to me like the above is > > > > redundant. > > > > > > Even at its original definition irq_data seems unlikely to be NULL: > > > struct s3c_irq_intc *intc = h->host_data; > > > > > > struct s3c_irq_data *irq_data = &intc->irqs[hw]; > > > ... > > > if (!irq_data) { > > > > > > pr_err("irq-s3c24xx: no irq data found for hwirq > > > %lu\n", > > > > > > hw); return -EINVAL; > > > > > > } > > > > > > That is, it could be an invalid value, but whether it actually hits 0 > > > would seem to depend on the value hw? > > > > > > Heiko, is NULL really a possibility? > > > > The test you quoted is of course wrong ... it would need to test > > parent_irq_data. But you're also right that the test is not necessary at > > all. > > > > All the s3c_irq_data arrays used always contain 32 entries to reach all > > bits of the register (which is used differently on each SoC). So if we > > have found the parent_intc at all, it should contain a 32 entries array > > of irq_data structs, so no need to test for the existence of the > > individual array element. > > > > > > And now that I look at it, I also see another glitch. The code tests for > > parent_irq != 0, which of course won't work if the parent_irq is the > > 0-hwirq of the parent controller. > > The only SoC using such a mapping is the s3c2412 [0], which explains why > > I haven't been bitten by this myself. > > Do you want to make all the fixes? Yep, I just need to find out what the best fix for my parent_irq mess up would be :-) The easiest way would of course be to use a value outside the valid range to indicate no parent-irq, so either < 0 (would need a type change) or > 32 . But I might be overlooking something here.