From 548de8acbf0137b6e49a14b63682badfff037d23 Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Mon, 27 Jan 2020 19:01:44 +0100 Subject: [PATCH 073/116] contrib/libvhost-user: Protect slave fd with mutex MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Dr. David Alan Gilbert Message-id: <20200127190227.40942-70-dgilbert@redhat.com> Patchwork-id: 93523 O-Subject: [RHEL-AV-8.2 qemu-kvm PATCH 069/112] contrib/libvhost-user: Protect slave fd with mutex Bugzilla: 1694164 RH-Acked-by: Philippe Mathieu-Daudé RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Sergio Lopez Pascual From: "Dr. David Alan Gilbert" In future patches we'll be performing commands on the slave-fd driven by commands on queues, since those queues will be driven by individual threads we need to make sure they don't attempt to use the slave-fd for multiple commands in parallel. Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Daniel P. Berrangé Signed-off-by: Dr. David Alan Gilbert (cherry picked from commit c25c02b9e6a196be87a818f459c426556b24770d) Signed-off-by: Miroslav Rezanina --- contrib/libvhost-user/libvhost-user.c | 24 ++++++++++++++++++++---- contrib/libvhost-user/libvhost-user.h | 3 +++ 2 files changed, 23 insertions(+), 4 deletions(-) diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c index ec27b78..63e4106 100644 --- a/contrib/libvhost-user/libvhost-user.c +++ b/contrib/libvhost-user/libvhost-user.c @@ -392,26 +392,37 @@ vu_send_reply(VuDev *dev, int conn_fd, VhostUserMsg *vmsg) return vu_message_write(dev, conn_fd, vmsg); } +/* + * Processes a reply on the slave channel. + * Entered with slave_mutex held and releases it before exit. + * Returns true on success. + */ static bool vu_process_message_reply(VuDev *dev, const VhostUserMsg *vmsg) { VhostUserMsg msg_reply; + bool result = false; if ((vmsg->flags & VHOST_USER_NEED_REPLY_MASK) == 0) { - return true; + result = true; + goto out; } if (!vu_message_read(dev, dev->slave_fd, &msg_reply)) { - return false; + goto out; } if (msg_reply.request != vmsg->request) { DPRINT("Received unexpected msg type. Expected %d received %d", vmsg->request, msg_reply.request); - return false; + goto out; } - return msg_reply.payload.u64 == 0; + result = msg_reply.payload.u64 == 0; + +out: + pthread_mutex_unlock(&dev->slave_mutex); + return result; } /* Kick the log_call_fd if required. */ @@ -1105,10 +1116,13 @@ bool vu_set_queue_host_notifier(VuDev *dev, VuVirtq *vq, int fd, return false; } + pthread_mutex_lock(&dev->slave_mutex); if (!vu_message_write(dev, dev->slave_fd, &vmsg)) { + pthread_mutex_unlock(&dev->slave_mutex); return false; } + /* Also unlocks the slave_mutex */ return vu_process_message_reply(dev, &vmsg); } @@ -1628,6 +1642,7 @@ vu_deinit(VuDev *dev) close(dev->slave_fd); dev->slave_fd = -1; } + pthread_mutex_destroy(&dev->slave_mutex); if (dev->sock != -1) { close(dev->sock); @@ -1663,6 +1678,7 @@ vu_init(VuDev *dev, dev->remove_watch = remove_watch; dev->iface = iface; dev->log_call_fd = -1; + pthread_mutex_init(&dev->slave_mutex, NULL); dev->slave_fd = -1; dev->max_queues = max_queues; diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h index 46b6007..1844b6f 100644 --- a/contrib/libvhost-user/libvhost-user.h +++ b/contrib/libvhost-user/libvhost-user.h @@ -19,6 +19,7 @@ #include #include #include +#include #include "standard-headers/linux/virtio_ring.h" /* Based on qemu/hw/virtio/vhost-user.c */ @@ -355,6 +356,8 @@ struct VuDev { VuVirtq *vq; VuDevInflightInfo inflight_info; int log_call_fd; + /* Must be held while using slave_fd */ + pthread_mutex_t slave_mutex; int slave_fd; uint64_t log_size; uint8_t *log_table; -- 1.8.3.1