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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 1C9A5C3A5A9 for ; Mon, 4 May 2020 18:04:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F274A20721 for ; Mon, 4 May 2020 18:04:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588615485; bh=bJ2l/CHYhXqqCQmXxTph5G9oI6DoxV3kjVdO3Qi3s38=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JjWMWIEjGrWQH3NpF0vzWaDFwrlSYAM4aPzpCZ1KnNEYWF9iat9lIKfztZqGa0Sqp 52RiJRHHph2mPrCbVpSWSveRnjGmEjbz4M3HIl+GlIJTNvtxhtKld8MMafBnntgKB/ t87pNiFcI/F2T1ISHypQ3RfDBp28kk5ZFqjf+T9w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731707AbgEDSEn (ORCPT ); Mon, 4 May 2020 14:04:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:34112 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731693AbgEDSEj (ORCPT ); Mon, 4 May 2020 14:04:39 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AF5E6205ED; Mon, 4 May 2020 18:04:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588615479; bh=bJ2l/CHYhXqqCQmXxTph5G9oI6DoxV3kjVdO3Qi3s38=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cHBqgI+0OkFMzZMSIPSqCBeA3ZVFIfX/LpJ5FI+V04oJddoYeN1fX1qJIMqQO3GId cVFOpJFwyHrUfrMvT/4Czd/q8Q0mOJryKkfLdWUf2heVo9lsbRrv7DL2aLScT97vBw ibbvU4e8rSrbsIfZpYU259ke6WJ0HUTztGZIu+EI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Seraj Alijan , Andy Shevchenko , Vinod Koul Subject: [PATCH 5.4 55/57] dmaengine: dmatest: Fix process hang when reading wait parameter Date: Mon, 4 May 2020 19:57:59 +0200 Message-Id: <20200504165501.618491542@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200504165456.783676004@linuxfoundation.org> References: <20200504165456.783676004@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andy Shevchenko commit aa72f1d20ee973d68f26d46fce5e1cf6f9b7e1ca upstream. If we do % echo 1 > /sys/module/dmatest/parameters/run [ 115.851124] dmatest: Could not start test, no channels configured % echo dma8chan7 > /sys/module/dmatest/parameters/channel [ 127.563872] dmatest: Added 1 threads using dma8chan7 % cat /sys/module/dmatest/parameters/wait ... !!! HANG !!! ... The culprit is the commit 6138f967bccc ("dmaengine: dmatest: Use fixed point div to calculate iops") which makes threads not to run, but pending and being kicked off by writing to the 'run' node. However, it forgot to consider 'wait' routine to avoid above mentioned case. In order to fix this, check for really running threads, i.e. with pending and done flags unset. It's pity the culprit commit hadn't updated documentation and tested all possible scenarios. Fixes: 6138f967bccc ("dmaengine: dmatest: Use fixed point div to calculate iops") Cc: Seraj Alijan Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20200428113518.70620-1-andriy.shevchenko@linux.intel.com Signed-off-by: Vinod Koul Signed-off-by: Greg Kroah-Hartman --- drivers/dma/dmatest.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/dma/dmatest.c +++ b/drivers/dma/dmatest.c @@ -240,7 +240,7 @@ static bool is_threaded_test_run(struct struct dmatest_thread *thread; list_for_each_entry(thread, &dtc->threads, node) { - if (!thread->done) + if (!thread->done && !thread->pending) return true; } }