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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 4827BC433F5 for ; Mon, 13 Sep 2021 12:21:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 33BEC60F58 for ; Mon, 13 Sep 2021 12:21:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239981AbhIMMWO (ORCPT ); Mon, 13 Sep 2021 08:22:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239960AbhIMMWH (ORCPT ); Mon, 13 Sep 2021 08:22:07 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36A52C061760 for ; Mon, 13 Sep 2021 05:20:51 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1631535649; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=va9U/DHN0OpTdBgoqRQ22J4VTELc5Rpzm1TiWJW6QJY=; b=DcpoVEnTVTkyr3ydMA/99Dppf/CBEwZOguQbtlQqe6eOay3r+IHA7kCAGZVgyXKJEefptF m0T9SLUs3ABhRfnOJ+g7GLnHRfurZLe7a7IwVEgf5dvoU6yhSSMDRqpkQOQu5nyH+54X1/ fX+xdkpbPhPbXtcdbtc1KgwIeZ+nEPcI9lqLuEbOhnSOywM3vzwL9wZs39hmWAo6vWRBUf cKPUO6VF58pshpJdhvqrGA8vnLZiXlloaMIBmcq5mIY//frmglWtBN4aUbHti6RjXgfbot gfRUS0TbmtIUi7Eh0xiVdv1ZK2p84Qp0Jp22/oIHiVe2BgbYpWsnvGEiAacCtg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1631535649; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=va9U/DHN0OpTdBgoqRQ22J4VTELc5Rpzm1TiWJW6QJY=; b=OjrtKrYvObEoH9DQb8bUfurrCAGOFSdORchdpbpnvXY2iSFyDcrsViYYUf3f5R9SosV6/o y1dGv68bMwAjjOAw== To: Davidlohr Bueso Cc: peterz@infradead.org, mingo@kernel.org, rostedt@goodmis.org, longman@redhat.com, bigeasy@linutronix.de, boqun.feng@gmail.com, dave@stgolabs.net, linux-kernel@vger.kernel.org, Davidlohr Bueso Subject: Re: [PATCH 2/2] locking/rwbase_rt: Lockless reader waking up a writer In-Reply-To: <20210901222825.6313-3-dave@stgolabs.net> References: <20210901222825.6313-1-dave@stgolabs.net> <20210901222825.6313-3-dave@stgolabs.net> Date: Mon, 13 Sep 2021 14:20:49 +0200 Message-ID: <87ilz4fyzi.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 01 2021 at 15:28, Davidlohr Bueso wrote: > diff --git a/kernel/locking/rwbase_rt.c b/kernel/locking/rwbase_rt.c > index 4ba15088e640..3444bc709973 100644 > --- a/kernel/locking/rwbase_rt.c > +++ b/kernel/locking/rwbase_rt.c > @@ -141,6 +141,7 @@ static void __sched __rwbase_read_unlock(struct rwbase_rt *rwb, > { > struct rt_mutex_base *rtm = &rwb->rtmutex; > struct task_struct *owner; > + DEFINE_WAKE_Q(wake_q); > > raw_spin_lock_irq(&rtm->wait_lock); > /* > @@ -151,9 +152,10 @@ static void __sched __rwbase_read_unlock(struct rwbase_rt *rwb, > */ > owner = rt_mutex_owner(rtm); > if (owner) > - wake_up_state(owner, state); > + wake_q_add(&wake_q, owner); That's broken for rw_locks. See commit 456cfbc65cd072f4f53936ee5a37eb1447a7d3ba. Thanks, tglx