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=-14.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 44D6DC433DF for ; Wed, 29 Jul 2020 14:33:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 25E6522B49 for ; Wed, 29 Jul 2020 14:33:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="3njZXrv6"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="VB3PtjyK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727017AbgG2Odh (ORCPT ); Wed, 29 Jul 2020 10:33:37 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:42948 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726942AbgG2Odb (ORCPT ); Wed, 29 Jul 2020 10:33:31 -0400 Date: Wed, 29 Jul 2020 14:33:28 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1596033209; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TqKXNngZiFhVq+awtR9H3dRKe/CDQ0+Hgwc+V7U2sRA=; b=3njZXrv6Fb168eepwlb5iSDmz2S0PLrPC8fSS5LHJmqzILRiW8pOM+ncWgQuN8iAAql9/y kSPdVThAjTMb/aY+cbloWQncb+YeT61mFQOnY01ymFGN+Qqv2CKJI13Ahc8FXYox1Y7hM2 h6bjrY0hb7qmXzOCob+zYbLgcqgG940q2+eekHQFp5xKaGb70MWN2X6Fq10kapvVACEgKK g+LAu8ERvCfLGK5qZvI5T3V/yOiJSXsjhc6YTx5h/O0gz2cV6PwvkbM6pf9AymQQV+gY8a zqz4Q2WDEG/+n+8uFrAgYgAtEVXIhVmpScs1sQKQWFAKGmdExnD+50Bru8oCcA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1596033209; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TqKXNngZiFhVq+awtR9H3dRKe/CDQ0+Hgwc+V7U2sRA=; b=VB3PtjyKXgmMJLfnmiIyny7lS89vUQRUvdXkGoKQHWR+mId9Hzle7bT+f1lcFy809L2Mn4 cKB/iHeHqgRzKZBw== From: "tip-bot2 for Ahmed S. Darwish" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] userfaultfd: Use sequence counter with associated spinlock Cc: "Ahmed S. Darwish" , "Peter Zijlstra (Intel)" , x86 , LKML In-Reply-To: <20200720155530.1173732-23-a.darwish@linutronix.de> References: <20200720155530.1173732-23-a.darwish@linutronix.de> MIME-Version: 1.0 Message-ID: <159603320856.4006.8977304185444747615.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the locking/core branch of tip: Commit-ID: 2ca97ac8bdcc31fdc868f40c73c017f0a648dc07 Gitweb: https://git.kernel.org/tip/2ca97ac8bdcc31fdc868f40c73c017f0a648dc07 Author: Ahmed S. Darwish AuthorDate: Mon, 20 Jul 2020 17:55:28 +02:00 Committer: Peter Zijlstra CommitterDate: Wed, 29 Jul 2020 16:14:28 +02:00 userfaultfd: Use sequence counter with associated spinlock A sequence counter write side critical section must be protected by some form of locking to serialize writers. A plain seqcount_t does not contain the information of which lock must be held when entering a write side critical section. Use the new seqcount_spinlock_t data type, which allows to associate a spinlock with the sequence counter. This enables lockdep to verify that the spinlock used for writer serialization is held when the write side critical section is entered. If lockdep is disabled this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200720155530.1173732-23-a.darwish@linutronix.de --- fs/userfaultfd.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 52de290..26e8b23 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -61,7 +61,7 @@ struct userfaultfd_ctx { /* waitqueue head for events */ wait_queue_head_t event_wqh; /* a refile sequence protected by fault_pending_wqh lock */ - struct seqcount refile_seq; + seqcount_spinlock_t refile_seq; /* pseudo fd refcounting */ refcount_t refcount; /* userfaultfd syscall flags */ @@ -1998,7 +1998,7 @@ static void init_once_userfaultfd_ctx(void *mem) init_waitqueue_head(&ctx->fault_wqh); init_waitqueue_head(&ctx->event_wqh); init_waitqueue_head(&ctx->fd_wqh); - seqcount_init(&ctx->refile_seq); + seqcount_spinlock_init(&ctx->refile_seq, &ctx->fault_pending_wqh.lock); } SYSCALL_DEFINE1(userfaultfd, int, flags)