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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=no 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 DBA6CC433DF for ; Tue, 9 Jun 2020 16:59:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ABA9820760 for ; Tue, 9 Jun 2020 16:59:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591721958; bh=rGg4RVPuDPsCrypGxDIVSPgpmCXO9dRZpbAlRuILa0M=; h=Subject:From:To:Cc:Date:In-Reply-To:References:List-ID:From; b=OXnF3vc2RQEO2Jv9cCYCKJXUseAI67H4M4XUq7DvjK6CSwhOShCxKOveYnw3W5CFZ T+AJisKX+77+ejFN2ZP8L2a940UcgW04WpgIei04Ma42FcPOXzEvYte8mV4A85fft/ YNZ0f85OD3CW3yRdHKU4dTwmG2yYWMpOTPGS+StU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731339AbgFIQ7S (ORCPT ); Tue, 9 Jun 2020 12:59:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:55792 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731252AbgFIQ7N (ORCPT ); Tue, 9 Jun 2020 12:59:13 -0400 Received: from tzanussi-mobl (c-73-211-240-131.hsd1.il.comcast.net [73.211.240.131]) (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 69E3B2074B; Tue, 9 Jun 2020 16:59:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591721952; bh=rGg4RVPuDPsCrypGxDIVSPgpmCXO9dRZpbAlRuILa0M=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=fVmPylwSiI4UmjAsgCSTUu70Vkg+jsuNPWZrPmOJ7qbqannDQUr9GlGXa0+HGj3/2 fsfOvHb/p7cD6hS1n8OwjHzbcmNoOVsERkmHXi3NeADh3AB4gLDYFEd+2r5kqYZ1h4 rk+vdYbQ9+JkX9rtoq1M3H4JXcY5hwOYX4ohXgKA= Message-ID: <5ed2c074f367c2939d0cce494b85f9f5d74d4234.camel@kernel.org> Subject: Re: [4.19 stable-rt PATCH] tasklet: Fix UP case for tasklet CHAINED state From: Tom Zanussi To: Sebastian Andrzej Siewior Cc: linux-rt-users , LKML Date: Tue, 09 Jun 2020 11:59:11 -0500 In-Reply-To: <20200609163832.vicpmza6qgxalhmg@linutronix.de> References: <7642da1ef2578601d8c2b7bb739b0f8451e69bed.camel@kernel.org> <20200609163832.vicpmza6qgxalhmg@linutronix.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-rt-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org Hi Sebastian, On Tue, 2020-06-09 at 18:38 +0200, Sebastian Andrzej Siewior wrote: > On 2020-06-09 11:21:44 [-0500], Tom Zanussi wrote: > > index 73dae64bfc9c..4f37a6173ab9 100644 > > --- a/kernel/softirq.c > > +++ b/kernel/softirq.c > > @@ -947,10 +947,12 @@ static void __tasklet_schedule_common(struct > > tasklet_struct *t, > > * is locked before adding it to the list. > > */ > > if (test_bit(TASKLET_STATE_SCHED, &t->state)) { > > +#if defined(CONFIG_SMP) > > if (test_and_set_bit(TASKLET_STATE_CHAINED, &t->state)) > > { > > tasklet_unlock(t); > > return; > > } > > +#endif > > t->next = NULL; > > *head->tail = t; > > head->tail = &(t->next); > > @@ -1044,7 +1046,11 @@ static void tasklet_action_common(struct > > softirq_action *a, > > again: > > t->func(t->data); > > > > +#if !defined(CONFIG_SMP) > > + while (!tasklet_tryunlock(t)) { > > +#else > > while (cmpxchg(&t->state, TASKLET_STATEF_RC, 0) != > > TASKLET_STATEF_RC) { > > +#endif > > This is still needed for RT && !SMP > Yes, you're right - I'll change this and repost after testing all cases. Thanks, Tom > > /* > > * If it got disabled meanwhile, bail out: > > */ > > Sebastian