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[209.132.180.67]) by mx.google.com with ESMTP id o38-v6si4459351pgl.107.2018.10.24.03.52.41; Wed, 24 Oct 2018 03:52:56 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@nvidia.com header.s=n1 header.b=AEvGpH8Z; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727608AbeJXTT6 (ORCPT + 99 others); Wed, 24 Oct 2018 15:19:58 -0400 Received: from hqemgate15.nvidia.com ([216.228.121.64]:4967 "EHLO hqemgate15.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727356AbeJXTT5 (ORCPT ); Wed, 24 Oct 2018 15:19:57 -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 03:52:11 -0700 Received: from HQMAIL101.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Wed, 24 Oct 2018 03:52:20 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Wed, 24 Oct 2018 03:52:20 -0700 Received: from [10.21.132.148] (10.124.1.5) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Wed, 24 Oct 2018 10:52:19 +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> <4c318e6b-4841-dd52-d61d-1106c5f8afbc@nvidia.com> <11fc94af-efe2-e571-3163-efdaa91f34fc@gmail.com> From: Jon Hunter Message-ID: Date: Wed, 24 Oct 2018 11:52:17 +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: <11fc94af-efe2-e571-3163-efdaa91f34fc@gmail.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL104.nvidia.com (172.18.146.11) 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=1540378331; bh=pFDWAMRFBPe/b3rK9I6R7CXxwjIqImszqS/R/QfESJo=; 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=AEvGpH8ZkpzvK/VQBfJWK37336eaDKw9YXdRmdBCkVuACN82ErSvpnZEOGdZ+5AzH kzMSpGqdNDcorzl+pxtXf7gwvwUqlqTLZjwzpc7MDI8cHqd1IlNX+V/rNGTZ3s6VsV r21JTVaBdYSr8EOxwxBTVVZWo04Q1WcXE2TD9OKDNXLJE99O8zTV/1KK11zsVibB2h NDqNPm8ob8xsbz4m5cfBPvW9k/VIlVJ09i05w4gIcH59lroUbsLvHFSrn9a9wL9wEI rBJrEJrzmq1FoPUabgrOhkSQMG77rZer33jw6NlVQKFc/ZT/bdN+Rf2N/bberGZT9a thnsxwS7C7D6Q== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/10/2018 11:44, Dmitry Osipenko wrote: > On 10/24/18 1:20 PM, Jon Hunter wrote: >> >> 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); > > We can, but it is not necessary. Feel free to adjust the code as you wish while applying ;) I deliberately left the 'status' variable because I think that makes code a bit more expressive. Thierry, please feel free to add my ... Acked-by: Jon Hunter Personally I would drop the 'status' variable but up to you. Cheers Jon -- nvpublic