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 9BD30C04AA5 for ; Mon, 15 Oct 2018 12:52:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 61E862083C for ; Mon, 15 Oct 2018 12:52:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="pvvdKHxE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 61E862083C 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 S1726651AbeJOUhm (ORCPT ); Mon, 15 Oct 2018 16:37:42 -0400 Received: from hqemgate16.nvidia.com ([216.228.121.65]:3743 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726524AbeJOUhm (ORCPT ); Mon, 15 Oct 2018 16:37:42 -0400 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 15 Oct 2018 05:52:33 -0700 Received: from HQMAIL101.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Mon, 15 Oct 2018 05:52:29 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Mon, 15 Oct 2018 05:52:29 -0700 Received: from [10.21.132.143] (172.20.13.39) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Mon, 15 Oct 2018 12:52:28 +0000 Subject: Re: [PATCH v1 1/2] soc/tegra: pmc: Turn powergates_lock into spinlock To: Dmitry Osipenko , Thierry Reding CC: , References: <20180830183635.4474-1-digetx@gmail.com> From: Jon Hunter Message-ID: <7369869e-e58f-3760-d428-b00fb9cd28d9@nvidia.com> Date: Mon, 15 Oct 2018 13:52:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180830183635.4474-1-digetx@gmail.com> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL106.nvidia.com (172.18.146.12) 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=1539607953; bh=6nf17hdhxbaSY+GvZO+N8AA9KPNrMQsjq5O4L73TPEM=; 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=pvvdKHxEUFNhdbcfJGoYMU+ZoxW2JBiPaWrIaHNBgsp/+JkPtgS/QqVbQnWlnq5nX bzThRI5QY99zgVE0VZfsuIhTVfxpHAgQsRhAR8Em/ZOeIpVnbRwd+SXQDpQAg8VZbT Hy/3YWfV/jO55r+ESBSmljBE1kZcDa4QYxoQOJaoZCGVR6gDO6WlCTxjM7o8OxzyLt bGfuh9JRkYHpdEeWYb7fAht9WS3A9ghBdEWgSjYqqwfZrOHvsQugH9CdgDeURHxJPp Kw7un9A8l/zAigyIUyPaM2rDhbTCFys1Dw2LDAE92Wn/YXQiC5wWTIaEMvL+CwGGiu BZNN5PfMLva2Q== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30/08/18 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. > > 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) Given the above, rather than converting to a spinlock I wonder if we are just better off dropping the mutex completely from tegra_powergate_is_powered()? Otherwise ... > Signed-off-by: Dmitry Osipenko > --- > drivers/soc/tegra/pmc.c | 36 ++++++++++++++++++------------------ > 1 file changed, 18 insertions(+), 18 deletions(-) > > diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c > index 2d6f3fcf3211..d6bc9f66f1cd 100644 > --- a/drivers/soc/tegra/pmc.c > +++ b/drivers/soc/tegra/pmc.c > @@ -186,7 +186,7 @@ struct tegra_pmc_soc { > * @lp0_vec_phys: physical base address of the LP0 warm boot code > * @lp0_vec_size: size of the LP0 warm boot code > * @powergates_available: Bitmap of available power gates > - * @powergates_lock: mutex for power gate register access > + * @powergates_lock: lock for power gate register access > */ > struct tegra_pmc { > struct device *dev; > @@ -215,7 +215,7 @@ struct tegra_pmc { > u32 lp0_vec_size; > DECLARE_BITMAP(powergates_available, TEGRA_POWERGATE_MAX); > > - struct mutex powergates_lock; > + spinlock_t powergates_lock; > }; > > static struct tegra_pmc *pmc = &(struct tegra_pmc) { > @@ -288,10 +288,10 @@ static int tegra_powergate_set(unsigned int id, bool new_state) > if (id == TEGRA_POWERGATE_3D && pmc->soc->has_gpu_clamps) > return -EINVAL; > > - mutex_lock(&pmc->powergates_lock); > + spin_lock(&pmc->powergates_lock); > > if (tegra_powergate_state(id) == new_state) { > - mutex_unlock(&pmc->powergates_lock); > + spin_unlock(&pmc->powergates_lock); > return 0; > } > > @@ -300,7 +300,7 @@ static int tegra_powergate_set(unsigned int id, bool new_state) > err = readx_poll_timeout(tegra_powergate_state, id, status, > status == new_state, 10, 100000); > > - mutex_unlock(&pmc->powergates_lock); > + spin_unlock(&pmc->powergates_lock); ... the above readx_poll_timeout needs to be converted to the atomic version. Furthermore, the above 100ms timeout is probably not suited to spinlock. Cheers Jon -- nvpublic