[PATCH v3 3/5] vhost: hide synchronization within FD manager

[Maxime Coquelin <maxime.coquelin@redhat.com>]

This patch forces synchronization for all FDs additions
or deletions in the FD set. With that, it is no more
necessary for the user to know about the FD set pipe, so
hide its initialization in the FD manager.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/vhost/fd_man.c | 180 ++++++++++++++++++++++++---------------------
 lib/vhost/fd_man.h |   8 +-
 lib/vhost/socket.c |  12 +--
 lib/vhost/vduse.c  |  18 +----
 4 files changed, 101 insertions(+), 117 deletions(-)

diff --git a/lib/vhost/fd_man.c b/lib/vhost/fd_man.c
index e42c491fdb..0ae481b785 100644
--- a/lib/vhost/fd_man.c
+++ b/lib/vhost/fd_man.c
@@ -2,7 +2,9 @@
  * Copyright(c) 2010-2014 Intel Corporation
  */
 
+#include <errno.h>
 #include <stdio.h>
+#include <string.h>
 #include <unistd.h>
 
 #include <rte_common.h>
@@ -17,6 +19,87 @@ RTE_LOG_REGISTER_SUFFIX(vhost_fdset_logtype, fdset, INFO);
 
 #define FDPOLLERR (POLLERR | POLLHUP | POLLNVAL)
 
+static void
+fdset_pipe_read_cb(int readfd, void *dat,
+		   int *remove __rte_unused)
+{
+	char charbuf[16];
+	struct fdset *fdset = dat;
+	int r = read(readfd, charbuf, sizeof(charbuf));
+	/*
+	 * Just an optimization, we don't care if read() failed
+	 * so ignore explicitly its return value to make the
+	 * compiler happy
+	 */
+	RTE_SET_USED(r);
+
+	pthread_mutex_lock(&fdset->sync_mutex);
+	fdset->sync = true;
+	pthread_cond_broadcast(&fdset->sync_cond);
+	pthread_mutex_unlock(&fdset->sync_mutex);
+}
+
+static void
+fdset_pipe_uninit(struct fdset *fdset)
+{
+	fdset_del(fdset, fdset->u.readfd);
+	close(fdset->u.readfd);
+	fdset->u.readfd = -1;
+	close(fdset->u.writefd);
+	fdset->u.writefd = -1;
+}
+
+static int
+fdset_pipe_init(struct fdset *fdset)
+{
+	int ret;
+
+	pthread_mutex_init(&fdset->sync_mutex, NULL);
+	pthread_cond_init(&fdset->sync_cond, NULL);
+
+	if (pipe(fdset->u.pipefd) < 0) {
+		VHOST_FDMAN_LOG(ERR,
+			"failed to create pipe for vhost fdset");
+		return -1;
+	}
+
+	ret = fdset_add(fdset, fdset->u.readfd,
+			fdset_pipe_read_cb, NULL, fdset);
+	if (ret < 0) {
+		VHOST_FDMAN_LOG(ERR,
+			"failed to add pipe readfd %d into vhost server fdset",
+			fdset->u.readfd);
+
+		fdset_pipe_uninit(fdset);
+		return -1;
+	}
+
+	return 0;
+}
+
+static void
+fdset_sync(struct fdset *fdset)
+{
+	int ret;
+
+	pthread_mutex_lock(&fdset->sync_mutex);
+
+	fdset->sync = false;
+	ret = write(fdset->u.writefd, "1", 1);
+	if (ret < 0) {
+		VHOST_FDMAN_LOG(ERR,
+			"Failed to write to notification pipe: %s",
+			strerror(errno));
+		goto out_unlock;
+	}
+
+	while (!fdset->sync)
+		pthread_cond_wait(&fdset->sync_cond, &fdset->sync_mutex);
+
+out_unlock:
+	pthread_mutex_unlock(&fdset->sync_mutex);
+}
+
 static int
 get_last_valid_idx(struct fdset *pfdset, int last_valid_idx)
 {
@@ -96,6 +179,12 @@ fdset_add_fd(struct fdset *pfdset, int idx, int fd,
 	pfd->revents = 0;
 }
 
+void
+fdset_uninit(struct fdset *pfdset)
+{
+	fdset_pipe_uninit(pfdset);
+}
+
 int
 fdset_init(struct fdset *pfdset)
 {
@@ -106,8 +195,6 @@ fdset_init(struct fdset *pfdset)
 
 	pthread_mutex_init(&pfdset->fd_mutex, NULL);
 	pthread_mutex_init(&pfdset->fd_polling_mutex, NULL);
-	pthread_mutex_init(&pfdset->sync_mutex, NULL);
-	pthread_cond_init(&pfdset->sync_cond, NULL);
 
 	for (i = 0; i < MAX_FDS; i++) {
 		pfdset->fd[i].fd = -1;
@@ -115,7 +202,7 @@ fdset_init(struct fdset *pfdset)
 	}
 	pfdset->num = 0;
 
-	return 0;
+	return fdset_pipe_init(pfdset);
 }
 
 /**
@@ -145,6 +232,8 @@ fdset_add(struct fdset *pfdset, int fd, fd_cb rcb, fd_cb wcb, void *dat)
 	fdset_add_fd(pfdset, i, fd, rcb, wcb, dat);
 	pthread_mutex_unlock(&pfdset->fd_mutex);
 
+	fdset_sync(pfdset);
+
 	return 0;
 }
 
@@ -176,6 +265,8 @@ fdset_del(struct fdset *pfdset, int fd)
 		pthread_mutex_unlock(&pfdset->fd_mutex);
 	} while (i != -1);
 
+	fdset_sync(pfdset);
+
 	return dat;
 }
 
@@ -209,6 +300,9 @@ fdset_try_del(struct fdset *pfdset, int fd)
 	}
 
 	pthread_mutex_unlock(&pfdset->fd_mutex);
+
+	fdset_sync(pfdset);
+
 	return 0;
 }
 
@@ -314,83 +408,3 @@ fdset_event_dispatch(void *arg)
 
 	return 0;
 }
-
-static void
-fdset_pipe_read_cb(int readfd, void *dat,
-		   int *remove __rte_unused)
-{
-	char charbuf[16];
-	struct fdset *fdset = dat;
-	int r = read(readfd, charbuf, sizeof(charbuf));
-	/*
-	 * Just an optimization, we don't care if read() failed
-	 * so ignore explicitly its return value to make the
-	 * compiler happy
-	 */
-	RTE_SET_USED(r);
-
-	pthread_mutex_lock(&fdset->sync_mutex);
-	fdset->sync = true;
-	pthread_cond_broadcast(&fdset->sync_cond);
-	pthread_mutex_unlock(&fdset->sync_mutex);
-}
-
-void
-fdset_pipe_uninit(struct fdset *fdset)
-{
-	fdset_del(fdset, fdset->u.readfd);
-	close(fdset->u.readfd);
-	close(fdset->u.writefd);
-}
-
-int
-fdset_pipe_init(struct fdset *fdset)
-{
-	int ret;
-
-	if (pipe(fdset->u.pipefd) < 0) {
-		VHOST_FDMAN_LOG(ERR,
-			"failed to create pipe for vhost fdset");
-		return -1;
-	}
-
-	ret = fdset_add(fdset, fdset->u.readfd,
-			fdset_pipe_read_cb, NULL, fdset);
-
-	if (ret < 0) {
-		VHOST_FDMAN_LOG(ERR,
-			"failed to add pipe readfd %d into vhost server fdset",
-			fdset->u.readfd);
-
-		fdset_pipe_uninit(fdset);
-		return -1;
-	}
-
-	return 0;
-}
-
-void
-fdset_pipe_notify(struct fdset *fdset)
-{
-	int r = write(fdset->u.writefd, "1", 1);
-	/*
-	 * Just an optimization, we don't care if write() failed
-	 * so ignore explicitly its return value to make the
-	 * compiler happy
-	 */
-	RTE_SET_USED(r);
-}
-
-void
-fdset_pipe_notify_sync(struct fdset *fdset)
-{
-	pthread_mutex_lock(&fdset->sync_mutex);
-
-	fdset->sync = false;
-	fdset_pipe_notify(fdset);
-
-	while (!fdset->sync)
-		pthread_cond_wait(&fdset->sync_cond, &fdset->sync_mutex);
-
-	pthread_mutex_unlock(&fdset->sync_mutex);
-}
diff --git a/lib/vhost/fd_man.h b/lib/vhost/fd_man.h
index 0f4cddfe56..c18e3a435c 100644
--- a/lib/vhost/fd_man.h
+++ b/lib/vhost/fd_man.h
@@ -42,6 +42,7 @@ struct fdset {
 	bool sync;
 };
 
+void fdset_uninit(struct fdset *pfdset);
 
 int fdset_init(struct fdset *pfdset);
 
@@ -53,11 +54,4 @@ int fdset_try_del(struct fdset *pfdset, int fd);
 
 uint32_t fdset_event_dispatch(void *arg);
 
-int fdset_pipe_init(struct fdset *fdset);
-
-void fdset_pipe_uninit(struct fdset *fdset);
-
-void fdset_pipe_notify(struct fdset *fdset);
-void fdset_pipe_notify_sync(struct fdset *fdset);
-
 #endif
diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
index 8155749972..5afb952a21 100644
--- a/lib/vhost/socket.c
+++ b/lib/vhost/socket.c
@@ -278,7 +278,6 @@ vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
 	TAILQ_INSERT_TAIL(&vsocket->conn_list, conn, next);
 	pthread_mutex_unlock(&vsocket->conn_mutex);
 
-	fdset_pipe_notify(&vhost_user.fdset);
 	return;
 
 err_cleanup:
@@ -1186,20 +1185,11 @@ rte_vhost_driver_start(const char *path)
 			return -1;
 		}
 
-		/**
-		 * create a pipe which will be waited by poll and notified to
-		 * rebuild the wait list of poll.
-		 */
-		if (fdset_pipe_init(&vhost_user.fdset) < 0) {
-			VHOST_CONFIG_LOG(path, ERR, "failed to create pipe for vhost fdset");
-			return -1;
-		}
-
 		int ret = rte_thread_create_internal_control(&fdset_tid,
 				"vhost-evt", fdset_event_dispatch, &vhost_user.fdset);
 		if (ret != 0) {
 			VHOST_CONFIG_LOG(path, ERR, "failed to create fdset handling thread");
-			fdset_pipe_uninit(&vhost_user.fdset);
+			fdset_uninit(&vhost_user.fdset);
 			return -1;
 		}
 	}
diff --git a/lib/vhost/vduse.c b/lib/vhost/vduse.c
index 530c148399..d87fc500d4 100644
--- a/lib/vhost/vduse.c
+++ b/lib/vhost/vduse.c
@@ -225,7 +225,6 @@ vduse_vring_setup(struct virtio_net *dev, unsigned int index)
 			close(vq->kickfd);
 			vq->kickfd = VIRTIO_UNINITIALIZED_EVENTFD;
 		}
-		fdset_pipe_notify(&vduse.fdset);
 		vhost_enable_guest_notification(dev, vq, 1);
 		VHOST_CONFIG_LOG(dev->ifname, INFO, "Ctrl queue event handler installed");
 	}
@@ -238,10 +237,8 @@ vduse_vring_cleanup(struct virtio_net *dev, unsigned int index)
 	struct vduse_vq_eventfd vq_efd;
 	int ret;
 
-	if (vq == dev->cvq && vq->kickfd >= 0) {
+	if (vq == dev->cvq && vq->kickfd >= 0)
 		fdset_del(&vduse.fdset, vq->kickfd);
-		fdset_pipe_notify(&vduse.fdset);
-	}
 
 	vq_efd.index = index;
 	vq_efd.fd = VDUSE_EVENTFD_DEASSIGN;
@@ -432,20 +429,11 @@ vduse_device_create(const char *path, bool compliant_ol_flags)
 			return -1;
 		}
 
-		/**
-		 * create a pipe which will be waited by poll and notified to
-		 * rebuild the wait list of poll.
-		 */
-		if (fdset_pipe_init(&vduse.fdset) < 0) {
-			VHOST_CONFIG_LOG(path, ERR, "failed to create pipe for vduse fdset");
-			return -1;
-		}
-
 		ret = rte_thread_create_internal_control(&fdset_tid, "vduse-evt",
 				fdset_event_dispatch, &vduse.fdset);
 		if (ret != 0) {
 			VHOST_CONFIG_LOG(path, ERR, "failed to create vduse fdset handling thread");
-			fdset_pipe_uninit(&vduse.fdset);
+			fdset_uninit(&vduse.fdset);
 			return -1;
 		}
 
@@ -573,7 +561,6 @@ vduse_device_create(const char *path, bool compliant_ol_flags)
 				dev->vduse_dev_fd);
 		goto out_dev_destroy;
 	}
-	fdset_pipe_notify(&vduse.fdset);
 
 	free(dev_config);
 
@@ -616,7 +603,6 @@ vduse_device_destroy(const char *path)
 	vduse_device_stop(dev);
 
 	fdset_del(&vduse.fdset, dev->vduse_dev_fd);
-	fdset_pipe_notify_sync(&vduse.fdset);
 
 	if (dev->vduse_dev_fd >= 0) {
 		close(dev->vduse_dev_fd);
-- 
2.44.0