From patchwork Fri Jan 29 15:53:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kurz X-Patchwork-Id: 1433362 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) 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 ozlabs.org (Postfix) with ESMTPS id 4DS22C5Ytbz9rx6 for ; Sat, 30 Jan 2021 02:53:55 +1100 (AEDT) Received: from localhost ([::1]:32980 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l5W5o-0005jv-Pc for incoming@patchwork.ozlabs.org; Fri, 29 Jan 2021 10:53:52 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:60354) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l5W5Q-0005jb-HB for qemu-devel@nongnu.org; Fri, 29 Jan 2021 10:53:28 -0500 Received: from us-smtp-delivery-44.mimecast.com ([205.139.111.44]:30843) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l5W5M-0005nb-IT for qemu-devel@nongnu.org; Fri, 29 Jan 2021 10:53:28 -0500 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-436-KWEpAsTnPDW_QfAK1F7gFg-1; Fri, 29 Jan 2021 10:53:19 -0500 X-MC-Unique: KWEpAsTnPDW_QfAK1F7gFg-1 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 B2DC88066E9; Fri, 29 Jan 2021 15:53:18 +0000 (UTC) Received: from bahia.redhat.com (ovpn-112-162.ams2.redhat.com [10.36.112.162]) by smtp.corp.redhat.com (Postfix) with ESMTP id EFB7C60C15; Fri, 29 Jan 2021 15:53:13 +0000 (UTC) From: Greg Kurz To: qemu-devel@nongnu.org Subject: [PATCH] virtiofsd: vu_dispatch locking should never fail Date: Fri, 29 Jan 2021 16:53:12 +0100 Message-Id: <20210129155312.595980-1-groug@kaod.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kaod.org Received-SPF: softfail client-ip=205.139.111.44; envelope-from=groug@kaod.org; helo=us-smtp-delivery-44.mimecast.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_SOFTFAIL=0.665 autolearn=no 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: , Cc: Stefan Hajnoczi , "Dr. David Alan Gilbert" , Vivek Goyal , Greg Kurz Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" pthread_rwlock_rdlock() and pthread_rwlock_wrlock() can fail if a deadlock condition is detected or the current thread already owns the lock. They can also fail, like pthread_rwlock_unlock(), if the mutex wasn't properly initialized. None of these are ever expected to happen with fv_VuDev::vu_dispatch_rwlock. Some users already check the return value and assert, some others don't. Introduce rdlock/wrlock/unlock wrappers that just do the former and use them everywhere. Signed-off-by: Greg Kurz Reviewed-by: Vivek Goyal --- tools/virtiofsd/fuse_virtio.c | 42 +++++++++++++++++++++++------------ 1 file changed, 28 insertions(+), 14 deletions(-) diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c index ddcefee4272f..7ea269c4b65d 100644 --- a/tools/virtiofsd/fuse_virtio.c +++ b/tools/virtiofsd/fuse_virtio.c @@ -187,6 +187,24 @@ static void copy_iov(struct iovec *src_iov, int src_count, } } +/* + * pthread_rwlock_rdlock() and pthread_rwlock_wrlock can fail if + * a deadlock condition is detected or the current thread already + * owns the lock. They can also fail, like pthread_rwlock_unlock(), + * if the mutex wasn't properly initialized. None of these are ever + * expected to happen. + */ +#define VU_DISPATCH_LOCK_OP(op) \ +static inline void vu_dispatch_##op(struct fv_VuDev *vud) \ +{ \ + int ret = pthread_rwlock_##op(&vud->vu_dispatch_rwlock); \ + assert(ret == 0); \ +} + +VU_DISPATCH_LOCK_OP(rdlock); +VU_DISPATCH_LOCK_OP(wrlock); +VU_DISPATCH_LOCK_OP(unlock); + /* * Called back by ll whenever it wants to send a reply/message back * The 1st element of the iov starts with the fuse_out_header @@ -240,12 +258,12 @@ int virtio_send_msg(struct fuse_session *se, struct fuse_chan *ch, copy_iov(iov, count, in_sg, in_num, tosend_len); - pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock); + vu_dispatch_rdlock(qi->virtio_dev); pthread_mutex_lock(&qi->vq_lock); vu_queue_push(dev, q, elem, tosend_len); vu_queue_notify(dev, q); pthread_mutex_unlock(&qi->vq_lock); - pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock); + vu_dispatch_unlock(qi->virtio_dev); req->reply_sent = true; @@ -403,12 +421,12 @@ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch, ret = 0; - pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock); + vu_dispatch_rdlock(qi->virtio_dev); pthread_mutex_lock(&qi->vq_lock); vu_queue_push(dev, q, elem, tosend_len); vu_queue_notify(dev, q); pthread_mutex_unlock(&qi->vq_lock); - pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock); + vu_dispatch_unlock(qi->virtio_dev); err: if (ret == 0) { @@ -558,12 +576,12 @@ out: fuse_log(FUSE_LOG_DEBUG, "%s: elem %d no reply sent\n", __func__, elem->index); - pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock); + vu_dispatch_rdlock(qi->virtio_dev); pthread_mutex_lock(&qi->vq_lock); vu_queue_push(dev, q, elem, 0); vu_queue_notify(dev, q); pthread_mutex_unlock(&qi->vq_lock); - pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock); + vu_dispatch_unlock(qi->virtio_dev); } pthread_mutex_destroy(&req->ch.lock); @@ -596,7 +614,6 @@ static void *fv_queue_thread(void *opaque) qi->qidx, qi->kick_fd); while (1) { struct pollfd pf[2]; - int ret; pf[0].fd = qi->kick_fd; pf[0].events = POLLIN; @@ -645,8 +662,7 @@ static void *fv_queue_thread(void *opaque) break; } /* Mutual exclusion with virtio_loop() */ - ret = pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock); - assert(ret == 0); /* there is no possible error case */ + vu_dispatch_wrlock(qi->virtio_dev); pthread_mutex_lock(&qi->vq_lock); /* out is from guest, in is too guest */ unsigned int in_bytes, out_bytes; @@ -672,7 +688,7 @@ static void *fv_queue_thread(void *opaque) } pthread_mutex_unlock(&qi->vq_lock); - pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock); + vu_dispatch_unlock(qi->virtio_dev); /* Process all the requests. */ if (!se->thread_pool_size && req_list != NULL) { @@ -799,7 +815,6 @@ int virtio_loop(struct fuse_session *se) while (!fuse_session_exited(se)) { struct pollfd pf[1]; bool ok; - int ret; pf[0].fd = se->vu_socketfd; pf[0].events = POLLIN; pf[0].revents = 0; @@ -825,12 +840,11 @@ int virtio_loop(struct fuse_session *se) assert(pf[0].revents & POLLIN); fuse_log(FUSE_LOG_DEBUG, "%s: Got VU event\n", __func__); /* Mutual exclusion with fv_queue_thread() */ - ret = pthread_rwlock_wrlock(&se->virtio_dev->vu_dispatch_rwlock); - assert(ret == 0); /* there is no possible error case */ + vu_dispatch_wrlock(se->virtio_dev); ok = vu_dispatch(&se->virtio_dev->dev); - pthread_rwlock_unlock(&se->virtio_dev->vu_dispatch_rwlock); + vu_dispatch_unlock(se->virtio_dev); if (!ok) { fuse_log(FUSE_LOG_ERR, "%s: vu_dispatch failed\n", __func__);