From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754546Ab2COGKm (ORCPT ); Thu, 15 Mar 2012 02:10:42 -0400 Received: from mail1-relais-roc.national.inria.fr ([192.134.164.82]:49273 "EHLO mail1-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753171Ab2COGKj (ORCPT ); Thu, 15 Mar 2012 02:10:39 -0400 X-IronPort-AV: E=Sophos;i="4.73,588,1325458800"; d="scan'208";a="149470320" Date: Thu, 15 Mar 2012 07:10:36 +0100 (CET) From: Julia Lawall X-X-Sender: jll@localhost6.localdomain6 To: Guan Xuetao cc: Julia Lawall , Dan Carpenter , kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 7/7] arch/unicore32/kernel/dma.c: ensure arguments to request_irq and free_irq are compatible In-Reply-To: <1331773284.2389.61.camel@epip-laptop> Message-ID: References: <1331494587-12196-1-git-send-email-Julia.Lawall@lip6.fr> <1331494587-12196-8-git-send-email-Julia.Lawall@lip6.fr> <1331513926.2048.58.camel@epip-laptop> <1331622633.2048.87.camel@epip-laptop> <1331712444.2389.36.camel@epip-laptop> <20120314081910.GC3163@mwanda> <1331714575.2389.47.camel@epip-laptop> <1331773284.2389.61.camel@epip-laptop> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 15 Mar 2012, Guan Xuetao wrote: > On Wed, 2012-03-14 at 10:23 +0100, Julia Lawall wrote: >> >> On Wed, 14 Mar 2012, Guan Xuetao wrote: >> >>> On Wed, 2012-03-14 at 11:19 +0300, Dan Carpenter wrote: >>>> On Wed, Mar 14, 2012 at 04:07:24PM +0800, Guan Xuetao wrote: >>>>> puv3_init_dma() is called ONCE when initializing. >>>>> In logical, if request_irq(IRQ_DMAERR, *) failed, free_irq(IRQ_DMA, *) >>>>> is unnecessary, and dma device/driver can keep on working. >>>>> The patch could be: >>>>> ret = request_irq(IRQ_DMAERR, dma_err_handler, 0, "DMAERR", NULL); >>>>> if (ret) { >>>>> printk(KERN_CRIT "Can't register IRQ for DMAERR\n"); >>>>> - free_irq(IRQ_DMA, "DMA"); >>>>> return ret; >>>>> } >>>> >>>> It seems like you should remove the error return as well? >>>> >>>> regards, >>>> dan carpenter >>>> >>> The error return value will only generate an extra warning message, and >>> have no side-effect. >> >> The whole thing seems a little strange. I guess your point is that the >> call site never looks at the return value? Wouldn't it be better to make >> there be no return value in that case? If there is a return value, some >> calling context in the future might take that into account and then the >> lack of a free_irq would be a memory leak. Also if the first request_irq >> can never fail, perhaps that should be made explicit by not testing the >> return value? >> >> julia > This function is an init_call, not a probe function, and it is only > called ONCE. > The dma device here has two interrupts, one IRQ_DMA, another IRQ_DMAERR. > And the device could work without IRQ_DMAERR. > The return value should indicate whether there is something wrong during > initialization, so the function needs return errno when any request_irq > is failed. > For the first request_irq, some code has prepared its resources before > this call, so I suppose it successful. However, the return value must be > tested. OK, thank you for the explanation. I will change the patch. julia