From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5692DC004D3 for ; Wed, 24 Oct 2018 10:20:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1D8AE2075D for ; Wed, 24 Oct 2018 10:20:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="JDLQRPJO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1D8AE2075D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727156AbeJXSsF (ORCPT ); Wed, 24 Oct 2018 14:48:05 -0400 Received: from hqemgate15.nvidia.com ([216.228.121.64]:1165 "EHLO hqemgate15.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726676AbeJXSsE (ORCPT ); Wed, 24 Oct 2018 14:48:04 -0400 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate15.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Wed, 24 Oct 2018 03:20:24 -0700 Received: from HQMAIL101.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Wed, 24 Oct 2018 03:20:34 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Wed, 24 Oct 2018 03:20:34 -0700 Received: from [10.21.132.148] (172.20.13.39) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Wed, 24 Oct 2018 10:20:32 +0000 Subject: Re: [PATCH v1] soc/tegra: pmc: Drop locking from tegra_powergate_is_powered() To: Dmitry Osipenko , Thierry Reding CC: , References: <20181021183614.454-1-digetx@gmail.com> From: Jon Hunter Message-ID: <4c318e6b-4841-dd52-d61d-1106c5f8afbc@nvidia.com> Date: Wed, 24 Oct 2018 11:20:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181021183614.454-1-digetx@gmail.com> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL103.nvidia.com (172.20.187.11) To HQMAIL101.nvidia.com (172.20.187.10) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1540376425; bh=LE4wPlvTWOKwQHx9EFNZ3Y+bbhCweMHJhUFyRnB1sqU=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=JDLQRPJO4SawK3dysob57hI24VjGENnikP5o2HDOe/Z4V+NDqVNg932OZn0ViSvc5 xZM6swVerbjsfOUswmeRW/AO6110wRCzF0TAuJUt8LOt8KGw/OsOxKXM8L+oBQjkKv CAj2i/KH87YmulyRzOsHBDkXKoYzPEBRmouDcl1yKN5FfMyKVvEOtf36odP6z1jyoL 55lDVL92kmBHwphJfWGGBQYgM/tVbO1at03Pp+5hTQrWyG7phCNb5thXY5t53txnm3 w6LYE/EIgimL+fqn0fByJek9/uhRxznIQD3lcfzyvmguCgTSjs3XL03vlppCKkG+dH cVw0Fkuj6FGPQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/10/2018 19:36, Dmitry Osipenko wrote: > This fixes splats like the one below if CONFIG_DEBUG_ATOMIC_SLEEP=y > and machine (Tegra30) booted with SMP=n or all secondary CPU's are put > offline. Locking isn't needed because it protects atomic operation. > > # echo 0 | tee /sys/devices/system/cpu/cpu[1-3]/online > > BUG: sleeping function called from invalid context at kernel/locking/mutex.c:254 > in_atomic(): 1, irqs_disabled(): 128, pid: 0, name: swapper/0 > CPU: 0 PID: 0 Comm: swapper/0 Tainted: G C 4.18.0-next-20180821-00180-gc3ebb6544e44-dirty #823 > Hardware name: NVIDIA Tegra SoC (Flattened Device Tree) > [] (unwind_backtrace) from [] (show_stack+0x20/0x24) > [] (show_stack) from [] (dump_stack+0x94/0xa8) > [] (dump_stack) from [] (___might_sleep+0x13c/0x174) > [] (___might_sleep) from [] (__might_sleep+0x70/0xa8) > [] (__might_sleep) from [] (mutex_lock+0x2c/0x70) > [] (mutex_lock) from [] (tegra_powergate_is_powered+0x44/0xa8) > [] (tegra_powergate_is_powered) from [] (tegra30_cpu_rail_off_ready+0x30/0x74) > [] (tegra30_cpu_rail_off_ready) from [] (tegra30_idle_lp2+0xa0/0x108) > [] (tegra30_idle_lp2) from [] (cpuidle_enter_state+0x140/0x540) > [] (cpuidle_enter_state) from [] (cpuidle_enter+0x40/0x4c) > [] (cpuidle_enter) from [] (call_cpuidle+0x30/0x48) > [] (call_cpuidle) from [] (do_idle+0x238/0x28c) > [] (do_idle) from [] (cpu_startup_entry+0x28/0x2c) > [] (cpu_startup_entry) from [] (rest_init+0xd8/0xdc) > [] (rest_init) from [] (start_kernel+0x41c/0x430) > > Signed-off-by: Dmitry Osipenko > --- > drivers/soc/tegra/pmc.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c > index 1fa840e3d930..1714cd818d69 100644 > --- a/drivers/soc/tegra/pmc.c > +++ b/drivers/soc/tegra/pmc.c > @@ -543,9 +543,7 @@ int tegra_powergate_is_powered(unsigned int id) > if (!tegra_powergate_is_valid(id)) > return -EINVAL; > > - mutex_lock(&pmc->powergates_lock); > status = tegra_powergate_state(id); > - mutex_unlock(&pmc->powergates_lock); > > return status; Can we just ... return tegra_powergate_state(id); Cheers Jon -- nvpublic