From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751243AbdAQKKb (ORCPT ); Tue, 17 Jan 2017 05:10:31 -0500 Received: from mail-pf0-f194.google.com ([209.85.192.194]:33634 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751129AbdAQKK2 (ORCPT ); Tue, 17 Jan 2017 05:10:28 -0500 Subject: Re: [PATCH v1] irqchip: irq-mips-gic:- Handle return NULL error from ioremap_nocache To: Marc Zyngier , tglx@linutronix.de, jason@lakedaemon.net, matt.redfearn@imgtec.com References: <1483949306-9712-1-git-send-email-arvind.yadav.cs@gmail.com> <120995f1-6cdb-9736-f6da-b85925f27451@arm.com> Cc: linux-kernel@vger.kernel.org From: Arvind Yadav Message-ID: <4b306a43-7b8f-e4c4-95f8-bb0cd52f4336@gmail.com> Date: Tue, 17 Jan 2017 15:40:02 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <120995f1-6cdb-9736-f6da-b85925f27451@arm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Matt, Please Acknowledge this. Regards Arvind Yadav On Monday 09 January 2017 02:30 PM, Marc Zyngier wrote: > On 09/01/17 08:08, Arvind Yadav wrote: >> Here, If ioremap_nocache will fail. It will return NULL. >> Kernel can run into a NULL-pointer dereference. >> This error check will avoid NULL pointer dereference. >> >> Signed-off-by: Arvind Yadav >> --- >> drivers/irqchip/irq-mips-gic.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c >> index c01c09e..eeea2e8 100644 >> --- a/drivers/irqchip/irq-mips-gic.c >> +++ b/drivers/irqchip/irq-mips-gic.c >> @@ -979,6 +979,8 @@ static void __init __gic_init(unsigned long gic_base_addr, >> __gic_base_addr = gic_base_addr; >> >> gic_base = ioremap_nocache(gic_base_addr, gic_addrspace_size); >> + if (!gic_base) >> + panic("Failed to map GIC memory"); > So you're replacing a panic due to dereferencing a NULL pointer with > another panic -- not much progress here. I appreciate that the message > is a bit more explicit, but is there something slightly less drastic we > could do? Like returning an error code and see if the kernel otherwise > recovers (possibly with reduced functionality)? > >> >> gicconfig = gic_read(GIC_REG(SHARED, GIC_SH_CONFIG)); >> gic_shared_intrs = (gicconfig & GIC_SH_CONFIG_NUMINTRS_MSK) >> >> > Thanks, > > M.