On Mon, 25 Jan 2021 13:01:11 -0500 Vivek Goyal <vgo...@redhat.com> wrote:
> dev->slave_mutex needs to be taken when sending messages on slave_fd. > Currently _vu_queue_notify() does not do that. > > Introduce a helper vu_message_slave_send_receive() which sends as well > as receive response. Use this helper in all the paths which send > message on slave_fd channel. > Does this fix any known bug ? > Signed-off-by: Vivek Goyal <vgo...@redhat.com> > --- LGTM Reviewed-by: Greg Kurz <gr...@kaod.org> > subprojects/libvhost-user/libvhost-user.c | 50 ++++++++++++----------- > 1 file changed, 27 insertions(+), 23 deletions(-) > > diff --git a/subprojects/libvhost-user/libvhost-user.c > b/subprojects/libvhost-user/libvhost-user.c > index 4cf4aef63d..7a56c56dc8 100644 > --- a/subprojects/libvhost-user/libvhost-user.c > +++ b/subprojects/libvhost-user/libvhost-user.c > @@ -403,7 +403,7 @@ vu_send_reply(VuDev *dev, int conn_fd, VhostUserMsg *vmsg) > * Processes a reply on the slave channel. > * Entered with slave_mutex held and releases it before exit. > * Returns true on success. > - * *payload is written on success > + * *payload is written on success, if payload is not NULL. > */ > static bool > vu_process_message_reply(VuDev *dev, const VhostUserMsg *vmsg, > @@ -427,7 +427,9 @@ vu_process_message_reply(VuDev *dev, const VhostUserMsg > *vmsg, > goto out; > } > > - *payload = msg_reply.payload.u64; > + if (payload) { > + *payload = msg_reply.payload.u64; > + } > result = true; > > out: > @@ -435,6 +437,25 @@ out: > return result; > } > > +/* Returns true on success, false otherwise */ > +static bool > +vu_message_slave_send_receive(VuDev *dev, VhostUserMsg *vmsg, uint64_t > *payload) > +{ > + pthread_mutex_lock(&dev->slave_mutex); > + if (!vu_message_write(dev, dev->slave_fd, vmsg)) { > + pthread_mutex_unlock(&dev->slave_mutex); > + return false; > + } > + > + if ((vmsg->flags & VHOST_USER_NEED_REPLY_MASK) == 0) { > + pthread_mutex_unlock(&dev->slave_mutex); > + return true; > + } > + > + /* Also unlocks the slave_mutex */ > + return vu_process_message_reply(dev, vmsg, payload); > +} > + > /* Kick the log_call_fd if required. */ > static void > vu_log_kick(VuDev *dev) > @@ -1340,16 +1361,8 @@ 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 */ > - res = vu_process_message_reply(dev, &vmsg, &payload); > + res = vu_message_slave_send_receive(dev, &vmsg, &payload); > res = res && (payload == 0); > - > return res; > } > > @@ -2395,10 +2408,7 @@ static void _vu_queue_notify(VuDev *dev, VuVirtq *vq, > bool sync) > vmsg.flags |= VHOST_USER_NEED_REPLY_MASK; > } > > - vu_message_write(dev, dev->slave_fd, &vmsg); > - if (ack) { > - vu_message_read_default(dev, dev->slave_fd, &vmsg); > - } > + vu_message_slave_send_receive(dev, &vmsg, NULL); > return; > } > > @@ -2942,17 +2952,11 @@ int64_t vu_fs_cache_request(VuDev *dev, > VhostUserSlaveRequest req, int fd, > return -EINVAL; > } > > - pthread_mutex_lock(&dev->slave_mutex); > - if (!vu_message_write(dev, dev->slave_fd, &vmsg)) { > - pthread_mutex_unlock(&dev->slave_mutex); > - return -EIO; > - } > - > - /* Also unlocks the slave_mutex */ > - res = vu_process_message_reply(dev, &vmsg, &payload); > + res = vu_message_slave_send_receive(dev, &vmsg, &payload); > if (!res) { > return -EIO; > } > + > /* > * Payload is delivered as uint64_t but is actually signed for > * errors.