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 C5E17EB64DD for ; Thu, 17 Aug 2023 07:00:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348335AbjHQHAQ (ORCPT ); Thu, 17 Aug 2023 03:00:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54564 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348333AbjHQG7z (ORCPT ); Thu, 17 Aug 2023 02:59:55 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 30BDB1BE8 for ; Wed, 16 Aug 2023 23:59:54 -0700 (PDT) Date: Thu, 17 Aug 2023 08:59:50 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1692255592; 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=lxW+gDxPMqz0DLwsVHLuGCjK8oTtiezcfKDHXgrXISE=; b=BRTuNmzjwHgmFC6/J7c1EpKCZrD/RBtQ42KQysc3tQlIGyH4mu6UGV5XOwdRUR7yEv1sIC T47t9kjzONGFuUA914XoxJIIxgyDZwjKCB9jVaxCA7Pn4b43kVHD2up7jJSrfik0xNLkam szv0V9tf8RjG4sz1NYUjcH1mZFz0E0YEK0pUVuuczmrXOcqBSs9NNiCIoAGU/D1+27Pw6b 54aAOEjhgZIkmW1DcqmBPUEvWL2MGRBK9WSHKHFijF5zuf2QQIt+0heBceMoklYr2Oe4Ao NSuuipAamO++M621S4BFof/izcbfUQeVustNW8hurPm79KbnrRrw+oB2so7lnw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1692255592; 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=lxW+gDxPMqz0DLwsVHLuGCjK8oTtiezcfKDHXgrXISE=; b=DoxYcSN4FwTM1Qws7jsOVSqU74QeKcPdGTk3wKl4GYJgbjmNLDy5RZ5Nbz3Wu4D5qj5s1u ICCe8qKic4KjPADw== From: Sebastian Andrzej Siewior To: Peter Zijlstra 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: <20230817065950.yWBqlw4Y@linutronix.de> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230816145818.GA989936@hirez.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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