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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 0499FC2BB1D for ; Tue, 7 Apr 2020 11:39:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C2D7D2063A for ; Tue, 7 Apr 2020 11:39:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GQg0noZP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726591AbgDGLjd (ORCPT ); Tue, 7 Apr 2020 07:39:33 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:51562 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726562AbgDGLjd (ORCPT ); Tue, 7 Apr 2020 07:39:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586259572; 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=SLWoZ7xBJlxppLjgO4JA0tZz9Q1hX/ECeYtU41moqKs=; b=GQg0noZPFiqj7odKkOh7xl2+VzWndPGDSJUzQGdDNR64gqMXLJy4lnBDzStbiYs1TJe5AA sBSXBa5DQ/sC1hy5bZBJoIVRhKH8TJZu4OBKHs2pwgigK1SxUJ6q5LERNG2oGIA8Rc5c5m D0m4N/gdqi656YGPuMEvkKemQAUVeio= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-427-tOWOb07lNp68_wsa40CMBA-1; Tue, 07 Apr 2020 07:39:29 -0400 X-MC-Unique: tOWOb07lNp68_wsa40CMBA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A45D71005510; Tue, 7 Apr 2020 11:39:28 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.196.88]) by smtp.corp.redhat.com (Postfix) with SMTP id 9803A5DA81; Tue, 7 Apr 2020 11:39:27 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 7 Apr 2020 13:39:28 +0200 (CEST) Date: Tue, 7 Apr 2020 13:39:27 +0200 From: Oleg Nesterov To: Jens Axboe Cc: io-uring@vger.kernel.org, peterz@infradead.org Subject: Re: [PATCH 2/4] task_work: don't run task_work if task_work_exited is queued Message-ID: <20200407113927.GB4506@redhat.com> References: <20200406194853.9896-1-axboe@kernel.dk> <20200406194853.9896-3-axboe@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200406194853.9896-3-axboe@kernel.dk> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 04/06, Jens Axboe wrote: > > +extern struct callback_head task_work_exited; > + > static inline void > init_task_work(struct callback_head *twork, task_work_func_t func) > { > @@ -19,7 +21,7 @@ void __task_work_run(void); > > static inline bool task_work_pending(void) > { > - return current->task_works; > + return current->task_works && current->task_works != &task_work_exited; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Well, this penalizes all the current users, they can't hit work_exited. IIUC, this is needed for the next change which adds task_work_run() into io_ring_ctx_wait_and_kill(), right? could you explain how the exiting can call io_ring_ctx_wait_and_kill() after it passed exit_task_work() ? Oleg.