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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 0AC00C2D0CE for ; Tue, 21 Jan 2020 14:21:51 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CC1A02070C for ; Tue, 21 Jan 2020 14:21:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="M5m6s3Jv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CC1A02070C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:55012 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ituPd-0000uT-Gg for qemu-devel@archiver.kernel.org; Tue, 21 Jan 2020 09:21:49 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:52966) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1itsiQ-00047L-Ul for qemu-devel@nongnu.org; Tue, 21 Jan 2020 07:33:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1itsiN-00055q-3P for qemu-devel@nongnu.org; Tue, 21 Jan 2020 07:33:06 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:38492 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1itsiM-00055m-Um for qemu-devel@nongnu.org; Tue, 21 Jan 2020 07:33:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579609982; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VaMuJQ0kEqF+Mn8YbHpGchU2mMcZGwcQFfJqCMKUjBY=; b=M5m6s3Jvylg2NSR83KprmJGetEmR2UtLfEwc/lRAE2jVITCaXsEPEMqF58H00Zcl3Ir8au DWm8ScUShmJ+is0Ry+Qhl0qVco8ivyLUEeya++E2YTRLOhUCZaoCIrnF3Vif96mU6waK7L cdvukopavUG1UD9ui+w6nzfNcV3xYe0= 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-226-FYKC2diNNCmf8XtOlb-Pyg-1; Tue, 21 Jan 2020 07:33:00 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6E6771005510; Tue, 21 Jan 2020 12:32:59 +0000 (UTC) Received: from dgilbert-t580.localhost (unknown [10.36.118.32]) by smtp.corp.redhat.com (Postfix) with ESMTP id 57C0F60BE0; Tue, 21 Jan 2020 12:32:52 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com, vgoyal@redhat.com, berrange@redhat.com, slp@redhat.com, philmd@redhat.com Subject: [PATCH v2 106/109] virtiofsd: Convert lo_destroy to take the lo->mutex lock itself Date: Tue, 21 Jan 2020 12:24:30 +0000 Message-Id: <20200121122433.50803-107-dgilbert@redhat.com> In-Reply-To: <20200121122433.50803-1-dgilbert@redhat.com> References: <20200121122433.50803-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: FYKC2diNNCmf8XtOlb-Pyg-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: m.mizuma@jp.fujitsu.com, misono.tomohiro@jp.fujitsu.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: "Dr. David Alan Gilbert" lo_destroy was relying on some implicit knowledge of the locking; we can avoid this if we create an unref_inode that doesn't take the lock and then grab it for the whole of the lo_destroy. Suggested-by: Vivek Goyal Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- tools/virtiofsd/passthrough_ll.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough= _ll.c index 4c656b4a60..3c450c15b4 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -1344,14 +1344,13 @@ static void lo_unlink(fuse_req_t req, fuse_ino_t pa= rent, const char *name) lo_inode_put(lo, &inode); } =20 -static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inod= e, - uint64_t n) +/* To be called with lo->mutex held */ +static void unref_inode(struct lo_data *lo, struct lo_inode *inode, uint64= _t n) { if (!inode) { return; } =20 - pthread_mutex_lock(&lo->mutex); assert(inode->nlookup >=3D n); inode->nlookup -=3D n; if (!inode->nlookup) { @@ -1362,15 +1361,24 @@ static void unref_inode_lolocked(struct lo_data *lo= , struct lo_inode *inode, } g_hash_table_destroy(inode->posix_locks); pthread_mutex_destroy(&inode->plock_mutex); - pthread_mutex_unlock(&lo->mutex); =20 /* Drop our refcount from lo_do_lookup() */ lo_inode_put(lo, &inode); - } else { - pthread_mutex_unlock(&lo->mutex); } } =20 +static void unref_inode_lolocked(struct lo_data *lo, struct lo_inode *inod= e, + uint64_t n) +{ + if (!inode) { + return; + } + + pthread_mutex_lock(&lo->mutex); + unref_inode(lo, inode, n); + pthread_mutex_unlock(&lo->mutex); +} + static void lo_forget_one(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup= ) { struct lo_data *lo =3D lo_data(req); @@ -2458,13 +2466,7 @@ static void lo_destroy(void *userdata) { struct lo_data *lo =3D (struct lo_data *)userdata; =20 - /* - * Normally lo->mutex must be taken when traversing lo->inodes but - * lo_destroy() is a serialized request so no races are possible here. - * - * In addition, we cannot acquire lo->mutex since unref_inode() takes = it - * too and this would result in a recursive lock. - */ + pthread_mutex_lock(&lo->mutex); while (true) { GHashTableIter iter; gpointer key, value; @@ -2475,8 +2477,9 @@ static void lo_destroy(void *userdata) } =20 struct lo_inode *inode =3D value; - unref_inode_lolocked(lo, inode, inode->nlookup); + unref_inode(lo, inode, inode->nlookup); } + pthread_mutex_unlock(&lo->mutex); } =20 static struct fuse_lowlevel_ops lo_oper =3D { --=20 2.24.1