Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964891AbdCWP1f (ORCPT ); Thu, 23 Mar 2017 11:27:35 -0400 Received: from mail-oi0-f65.google.com ([209.85.218.65]:36186 "EHLO mail-oi0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755909AbdCWP1d (ORCPT ); Thu, 23 Mar 2017 11:27:33 -0400 MIME-Version: 1.0 In-Reply-To: <20170323152247.14733-3-svaidy@linux.vnet.ibm.com> References: <20170323152247.14733-1-svaidy@linux.vnet.ibm.com> <20170323152247.14733-3-svaidy@linux.vnet.ibm.com> From: "Rafael J. Wysocki" Date: Thu, 23 Mar 2017 16:27:31 +0100 X-Google-Sender-Auth: oG5gO7rRfWGsXpYVP5YpbpgyBDU Message-ID: Subject: Re: [PATCH v2 2/2] cpuidle: Validate cpu_dev in cpuidle_add_sysfs To: Vaidyanathan Srinivasan Cc: Michael Neuling , Michael Ellerman , "Rafael J . Wysocki" , Daniel Lezcano , linuxppc-dev , Linux Kernel Mailing List , Linux PM Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3185 Lines: 76 On Thu, Mar 23, 2017 at 4:22 PM, Vaidyanathan Srinivasan wrote: > If a given cpu is not in cpu_present and cpu hotplug > is disabled, arch can skip setting up the cpu_dev. > > Arch cpuidle driver should pass correct cpu mask > for registration, but failing to do so by the driver > causes error to propagate and crash like this: > > [ 30.076045] Unable to handle kernel paging request for > data at address 0x00000048 > [ 30.076100] Faulting instruction address: 0xc0000000007b2f30 > cpu 0x4d: Vector: 300 (Data Access) at [c000003feb18b670] > pc: c0000000007b2f30: kobject_get+0x20/0x70 > lr: c0000000007b3c94: kobject_add_internal+0x54/0x3f0 > sp: c000003feb18b8f0 > msr: 9000000000009033 > dar: 48 > dsisr: 40000000 > current = 0xc000003fd2ed8300 > paca = 0xc00000000fbab500 softe: 0 irq_happened: 0x01 > pid = 1, comm = swapper/0 > Linux version 4.11.0-rc2-svaidy+ (sv@sagarika) (gcc version 6.2.0 > 20161005 (Ubuntu 6.2.0-5ubuntu12) ) #10 SMP Sun Mar 19 00:08:09 IST 2017 > enter ? for help > [c000003feb18b960] c0000000007b3c94 kobject_add_internal+0x54/0x3f0 > [c000003feb18b9f0] c0000000007b43a4 kobject_init_and_add+0x64/0xa0 > [c000003feb18ba70] c000000000e284f4 cpuidle_add_sysfs+0xb4/0x130 > [c000003feb18baf0] c000000000e26038 cpuidle_register_device+0x118/0x1c0 > [c000003feb18bb30] c000000000e26c48 cpuidle_register+0x78/0x120 > [c000003feb18bbc0] c00000000168fd9c powernv_processor_idle_init+0x110/0x1c4 > [c000003feb18bc40] c00000000000cff8 do_one_initcall+0x68/0x1d0 > [c000003feb18bd00] c0000000016242f4 kernel_init_freeable+0x280/0x360 > [c000003feb18bdc0] c00000000000d864 kernel_init+0x24/0x160 > [c000003feb18be30] c00000000000b4e8 ret_from_kernel_thread+0x5c/0x74 > > Validating cpu_dev fixes the crash and reports correct error message like: > > [ 30.163506] Failed to register cpuidle device for cpu136 > [ 30.173329] Registration of powernv driver failed. > > Signed-off-by: Vaidyanathan Srinivasan The previous version is in linux-next already and I'm going to push it for merging shortly. > --- > drivers/cpuidle/sysfs.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c > index c5adc8c..f2c3bce 100644 > --- a/drivers/cpuidle/sysfs.c > +++ b/drivers/cpuidle/sysfs.c > @@ -615,6 +615,18 @@ int cpuidle_add_sysfs(struct cpuidle_device *dev) > struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu); > int error; > > + /* > + * Return error if cpu_device is not setup for this cpu. This > + * could happen if arch did not setup cpu_device since this > + * cpu is not in cpu_present mask and the driver did not send > + * correct cpu mask at registration. Without this check we > + * would end up passing bogus value for &cpu_dev->kobj in > + * kobject_init_and_add(). > + */ > + > + if (!cpu_dev) > + return -ENODEV; > + > kdev = kzalloc(sizeof(*kdev), GFP_KERNEL); > if (!kdev) > return -ENOMEM; > -- > 2.9.3 >