From patchwork Sun Jul 19 13:20:11 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Schoenebeck X-Patchwork-Id: 277728 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=-10.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE autolearn=unavailable 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 4EA84C433DF for ; Sun, 19 Jul 2020 14:44:09 +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 178A62080D for ; Sun, 19 Jul 2020 14:44:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=crudebyte.com header.i=@crudebyte.com header.b="Zaa+7mWq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 178A62080D Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=crudebyte.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38254 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jxAXw-0007C1-Cw for qemu-devel@archiver.kernel.org; Sun, 19 Jul 2020 10:44:08 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40634) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jxAXO-0006lC-77 for qemu-devel@nongnu.org; Sun, 19 Jul 2020 10:43:34 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:33221) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jxAXM-0005au-LZ for qemu-devel@nongnu.org; Sun, 19 Jul 2020 10:43:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Cc:To:Subject:Date:From:References:In-Reply-To: Message-Id:Content-Type:Content-Transfer-Encoding:MIME-Version:Content-ID: Content-Description; bh=c2gjWlA9KXE9xMxvVd4GTnin4I8DBwh8bFZ8rcqFpbY=; b=Zaa+7 mWqz+AGuPgUQ9P3bXZE3jFPNn1Z/EPAMOZWbNGD7ogV+cZTtWZfbaJCJUrkp5hMW9xYwdOvnuJ9DS gKFSw8jjHsPlU+nc5ucCtZXBq9AR/UUOwuT3jp75FGy+iOfYDyKiaJn6WeQk4j9MYjKKX4DDq9PAE j53uw59aPJ7JblzKEjhgAPy58T6gIVPMtA3f5LwjiKQhkQP71/I/vIDMuqXvBseVOkocT109II6tD TgR3ru+LatJVpOpLnyNUc2XFjEfnVNafgH3mAZqNWBzW/xgjpMmd0y1r0ls+ky/1MP6K4BJpQl13n GghQLcR1Calqj911PZI0ixbmODDFg==; Message-Id: In-Reply-To: References: From: Christian Schoenebeck Date: Sun, 19 Jul 2020 15:20:11 +0200 Subject: [PATCH v7 5/6] 9pfs: differentiate readdir lock between 9P2000.u vs. 9P2000.L To: qemu-devel@nongnu.org Cc: Greg Kurz Received-SPF: none client-ip=91.194.90.13; envelope-from=abccfcad6764986c8442f2163de618af11232475@lizzy.crudebyte.com; helo=lizzy.crudebyte.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/19 10:12:15 X-ACL-Warn: Detected OS = Linux 3.11 and newer X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_NONE=0.001, URIBL_BLOCKED=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Previous patch suggests that it might make sense to use a different mutex type now while handling readdir requests, depending on the precise protocol variant, as v9fs_do_readdir_with_stat() (used by 9P2000.u) uses a CoMutex to avoid deadlocks that might happen with QemuMutex otherwise, whereas do_readdir_many() (used by 9P2000.L) should better use a QemuMutex, as the precise behaviour of a failed CoMutex lock on fs driver side would not be clear. This patch is just intended as transitional measure, as currently 9P2000.u vs. 9P2000.L implementations currently differ where the main logic of fetching directory entries is located at (9P2000.u still being more top half focused, while 9P2000.L already being bottom half focused in regards to fetching directory entries that is). Signed-off-by: Christian Schoenebeck --- hw/9pfs/9p.c | 4 ++-- hw/9pfs/9p.h | 27 ++++++++++++++++++++++----- 2 files changed, 24 insertions(+), 7 deletions(-) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index cc4094b971..a0881ddc88 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -314,8 +314,8 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid) f->next = s->fid_list; s->fid_list = f; - v9fs_readdir_init(&f->fs.dir); - v9fs_readdir_init(&f->fs_reclaim.dir); + v9fs_readdir_init(s->proto_version, &f->fs.dir); + v9fs_readdir_init(s->proto_version, &f->fs_reclaim.dir); return f; } diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h index 93b7030edf..3dd1b50b1a 100644 --- a/hw/9pfs/9p.h +++ b/hw/9pfs/9p.h @@ -197,22 +197,39 @@ typedef struct V9fsXattr typedef struct V9fsDir { DIR *stream; - CoMutex readdir_mutex; + P9ProtoVersion proto_version; + /* readdir mutex type used for 9P2000.u protocol variant */ + CoMutex readdir_mutex_u; + /* readdir mutex type used for 9P2000.L protocol variant */ + QemuMutex readdir_mutex_L; } V9fsDir; static inline void v9fs_readdir_lock(V9fsDir *dir) { - qemu_co_mutex_lock(&dir->readdir_mutex); + if (dir->proto_version == V9FS_PROTO_2000U) { + qemu_co_mutex_lock(&dir->readdir_mutex_u); + } else { + qemu_mutex_lock(&dir->readdir_mutex_L); + } } static inline void v9fs_readdir_unlock(V9fsDir *dir) { - qemu_co_mutex_unlock(&dir->readdir_mutex); + if (dir->proto_version == V9FS_PROTO_2000U) { + qemu_co_mutex_unlock(&dir->readdir_mutex_u); + } else { + qemu_mutex_unlock(&dir->readdir_mutex_L); + } } -static inline void v9fs_readdir_init(V9fsDir *dir) +static inline void v9fs_readdir_init(P9ProtoVersion proto_version, V9fsDir *dir) { - qemu_co_mutex_init(&dir->readdir_mutex); + dir->proto_version = proto_version; + if (proto_version == V9FS_PROTO_2000U) { + qemu_co_mutex_init(&dir->readdir_mutex_u); + } else { + qemu_mutex_init(&dir->readdir_mutex_L); + } } /**