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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE87DC2FC14 for ; Thu, 17 Aug 2023 08:27:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348875AbjHQI04 (ORCPT ); Thu, 17 Aug 2023 04:26:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348928AbjHQI0u (ORCPT ); Thu, 17 Aug 2023 04:26:50 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CCF252D57 for ; Thu, 17 Aug 2023 01:26:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=lpifKDNfNsjXFi7rqljZ8oYIHrqoai0CKoqISv9FVD8=; b=eHU9N1162rWS9hQb47I9N3eZfn KCkEaxeQFBdjSf7T9U4D7AMMjLJvfQPai0FeREvq7MnUIVd2Q83ZDsoUeigCRCnmPiyih2pRuIxv9 06z9o07WjY98dYRixbnKnmpvq47ai4wAfeNlp9NcMmBb/X/SvF4oLNXLRNaGJaGvHS6wI6tH3r/g5 q5mpmyWTCO3qQrEPMb6INQW05+dDpQe+B6AMMn3ienNTqKy1aIW9Hf32KmoYEtB6DbN9fPl945ix1 ALpXMYS4QhNvcasyumqfsxsaIR9iN2XUG+kN8yB7CWsgO4MTP14TG9JKwsOjmC29AgEdEQXUY8281 D+GDa3RA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1qWYKv-002CrR-BK; Thu, 17 Aug 2023 08:26:33 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 63C133001FD; Thu, 17 Aug 2023 10:26:32 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 22707207F09A9; Thu, 17 Aug 2023 10:26:32 +0200 (CEST) Date: Thu, 17 Aug 2023 10:26:32 +0200 From: Peter Zijlstra To: Sebastian Andrzej Siewior Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org, bsegall@google.com, boqun.feng@gmail.com, swood@redhat.com, bristot@redhat.com, dietmar.eggemann@arm.com, mingo@redhat.com, jstultz@google.com, juri.lelli@redhat.com, mgorman@suse.de, rostedt@goodmis.org, vschneid@redhat.com, vincent.guittot@linaro.org, longman@redhat.com, will@kernel.org Subject: Re: [PATCH 0/6] locking/rtmutex: Avoid PI state recursion through sched_submit_work() Message-ID: <20230817082632.GA1006598@hirez.programming.kicks-ass.net> References: <20230815110121.117752409@infradead.org> <20230815161557.GK214207@hirez.programming.kicks-ass.net> <20230816085826.zfXjhNmj@linutronix.de> <20230816094257.GE980931@hirez.programming.kicks-ass.net> <20230816101902.Pz8wdats@linutronix.de> <20230816134630.KO12Djeh@linutronix.de> <20230816145818.GA989936@hirez.programming.kicks-ass.net> <20230817065950.yWBqlw4Y@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230817065950.yWBqlw4Y@linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 17, 2023 at 08:59:50AM +0200, Sebastian Andrzej Siewior wrote: > On 2023-08-16 16:58:18 [+0200], Peter Zijlstra wrote: > > I've ended up with the below, but it is quite horrible.. but let me go > > stare at the futex wreckage before trying to clean things up. > > What about Ah, of course, that's much nicer. I got hung up on that rwbase_rtmutex_lock_state() thing :/ > diff --git a/kernel/locking/rwbase_rt.c b/kernel/locking/rwbase_rt.c > index f8a194e7ec9e9..b5e881250fec5 100644 > --- a/kernel/locking/rwbase_rt.c > +++ b/kernel/locking/rwbase_rt.c > @@ -241,6 +241,8 @@ static int __sched rwbase_write_lock(struct rwbase_rt *rwb, > /* Force readers into slow path */ > atomic_sub(READER_BIAS, &rwb->readers); > > + rt_mutex_pre_schedule(); > + > raw_spin_lock_irqsave(&rtm->wait_lock, flags); > if (__rwbase_write_trylock(rwb)) > goto out_unlock; > @@ -252,6 +254,7 @@ static int __sched rwbase_write_lock(struct rwbase_rt *rwb, > if (rwbase_signal_pending_state(state, current)) { > rwbase_restore_current_state(); > __rwbase_write_unlock(rwb, 0, flags); > + rt_mutex_post_schedule(); > trace_contention_end(rwb, -EINTR); > return -EINTR; > } > @@ -270,6 +273,7 @@ static int __sched rwbase_write_lock(struct rwbase_rt *rwb, > > out_unlock: > raw_spin_unlock_irqrestore(&rtm->wait_lock, flags); > + rt_mutex_post_schedule(); > return 0; > } > > Sebastian