From mboxrd@z Thu Jan 1 00:00:00 1970 From: Krzysztof Kozlowski Subject: Re: [PATCH v7 2/4] power: reset: add reboot mode driver Date: Wed, 06 Apr 2016 10:00:13 +0900 Message-ID: <57045F9D.1000502@samsung.com> References: <1459304304-9713-1-git-send-email-andy.yan@rock-chips.com> <1459304443-9811-1-git-send-email-andy.yan@rock-chips.com> <56FB49B3.2040505@samsung.com> <57045D6B.2080907@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:39351 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752206AbcDFBA2 (ORCPT ); Tue, 5 Apr 2016 21:00:28 -0400 In-reply-to: <57045D6B.2080907@rock-chips.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Andy Yan , robh+dt@kernel.org, sre@kernel.org, heiko@sntech.de, john.stultz@linaro.org, arnd@arndb.de Cc: mark.rutland@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, alexandre.belloni@free-electrons.com, f.fainelli@gmail.com, linux@arm.linux.org.uk, dbaryshkov@gmail.com, linux-pm@vger.kernel.org, linux-rockchip@lists.infradead.org, wxt@rock-chips.com, devicetree@vger.kernel.org, pawel.moll@arm.com, ijc+devicetree@hellion.org.uk, lorenzo.pieralisi@arm.com, matthias.bgg@gmail.com, linux-arm-kernel@lists.infradead.org, moritz.fischer@ettus.com, mbrugger@suse.com, linux-kernel@vger.kernel.org, galak@codeaurora.org, olof@lixom.net, jun.nie@linaro.org, dwmw2@infradead.org On 06.04.2016 09:50, Andy Yan wrote: (...) >>> + return -ENOMEM; >>> + >>> + info->mode = kstrdup_const(prop->name + len, GFP_KERNEL); >>> + if (of_property_read_u32(np, prop->name, &info->magic)) { >>> + dev_err(dev, "reboot mode %s without magic number\n", >>> + info->mode); >>> + devm_kfree(dev, info); >>> + continue; >>> + } >>> + list_add_tail(&info->list, &reboot->head); >>> + } >>> + of_node_put(np); >> If you of_node_put() here, there is no sense in getting it before. I >> mentioned of_node_get() only because I am not sure about life-cycle of >> nodes in case of DT overlays and you are storing the pointer to string >> from DT. >> >> The doubts I have are concerning only the case of freeing nodes from >> overlay. >> >> I don't know if of_node_get() is needed but of_node_get()+of_node_put() >> seems useless. > > > I am also not sure about it. Maybe just drop of_node_get/put ? OK, let's drop both get() and put(). (...) >>> + >>> +static const struct of_device_id syscon_reboot_mode_of_match[] = { >>> + { .compatible = "syscon-reboot-mode" }, >>> + {} >>> +}; >>> + >>> +static struct platform_driver syscon_reboot_mode_driver = { >>> + .probe = syscon_reboot_mode_probe, >> Cleanup needed. What will happen after device unbind? Memory will be >> released (devm-*()) but reboot notifier won't thus leading to OOPS on >> reboot. > > From the kernel_restart_prepare function, the reboot notifier will > be called before device_shutdown. Is there any other case the device > unbind before reboot notifier > called? This is a regular module platform driver so unbind can happen any time initiated by user, either by unbind command or by module removal. User can then re-bind device or not - probably does not matter. Anyway after such first unbind, the restart will kaboom instead of do a restart. Beside that, you always should clean up, regardless of restart or not. If you do not want unbind (thus no need of cleanup) then forbid it by making it a non-module with suppressed bind. Best regards, Krzysztof From mboxrd@z Thu Jan 1 00:00:00 1970 From: k.kozlowski@samsung.com (Krzysztof Kozlowski) Date: Wed, 06 Apr 2016 10:00:13 +0900 Subject: [PATCH v7 2/4] power: reset: add reboot mode driver In-Reply-To: <57045D6B.2080907@rock-chips.com> References: <1459304304-9713-1-git-send-email-andy.yan@rock-chips.com> <1459304443-9811-1-git-send-email-andy.yan@rock-chips.com> <56FB49B3.2040505@samsung.com> <57045D6B.2080907@rock-chips.com> Message-ID: <57045F9D.1000502@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 06.04.2016 09:50, Andy Yan wrote: (...) >>> + return -ENOMEM; >>> + >>> + info->mode = kstrdup_const(prop->name + len, GFP_KERNEL); >>> + if (of_property_read_u32(np, prop->name, &info->magic)) { >>> + dev_err(dev, "reboot mode %s without magic number\n", >>> + info->mode); >>> + devm_kfree(dev, info); >>> + continue; >>> + } >>> + list_add_tail(&info->list, &reboot->head); >>> + } >>> + of_node_put(np); >> If you of_node_put() here, there is no sense in getting it before. I >> mentioned of_node_get() only because I am not sure about life-cycle of >> nodes in case of DT overlays and you are storing the pointer to string >> from DT. >> >> The doubts I have are concerning only the case of freeing nodes from >> overlay. >> >> I don't know if of_node_get() is needed but of_node_get()+of_node_put() >> seems useless. > > > I am also not sure about it. Maybe just drop of_node_get/put ? OK, let's drop both get() and put(). (...) >>> + >>> +static const struct of_device_id syscon_reboot_mode_of_match[] = { >>> + { .compatible = "syscon-reboot-mode" }, >>> + {} >>> +}; >>> + >>> +static struct platform_driver syscon_reboot_mode_driver = { >>> + .probe = syscon_reboot_mode_probe, >> Cleanup needed. What will happen after device unbind? Memory will be >> released (devm-*()) but reboot notifier won't thus leading to OOPS on >> reboot. > > From the kernel_restart_prepare function, the reboot notifier will > be called before device_shutdown. Is there any other case the device > unbind before reboot notifier > called? This is a regular module platform driver so unbind can happen any time initiated by user, either by unbind command or by module removal. User can then re-bind device or not - probably does not matter. Anyway after such first unbind, the restart will kaboom instead of do a restart. Beside that, you always should clean up, regardless of restart or not. If you do not want unbind (thus no need of cleanup) then forbid it by making it a non-module with suppressed bind. Best regards, Krzysztof