[dpdk-dev] [PATCH v5 6/6] eal: ignore messages until init is complete

[Anatoly Burakov]

If we receive messages that don't have a callback registered for
them, and we haven't finished initialization yet, it can be reasonably
inferred that we shouldn't have gotten the message in the first
place. Therefore, send requester a special message telling them to
ignore response to this request, as if this process wasn't there.

Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
---

Notes:
    v5: add this patch
    
    No changes in mp_send and send_msg - just code move.

 lib/librte_eal/common/eal_common_proc.c | 280 +++++++++++++++++---------------
 1 file changed, 151 insertions(+), 129 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_proc.c b/lib/librte_eal/common/eal_common_proc.c
index fe27d68..1ea6045 100644
--- a/lib/librte_eal/common/eal_common_proc.c
+++ b/lib/librte_eal/common/eal_common_proc.c
@@ -52,6 +52,7 @@ enum mp_type {
 	MP_MSG, /* Share message with peers, will not block */
 	MP_REQ, /* Request for information, Will block for a reply */
 	MP_REP, /* Response to previously-received request */
+	MP_IGN, /* Response telling requester to ignore this response */
 };
 
 struct mp_msg_internal {
@@ -205,6 +206,130 @@ rte_mp_action_unregister(const char *name)
 	free(entry);
 }
 
+/**
+ * Return -1, as fail to send message and it's caused by the local side.
+ * Return 0, as fail to send message and it's caused by the remote side.
+ * Return 1, as succeed to send message.
+ *
+ */
+static int
+send_msg(const char *dst_path, struct rte_mp_msg *msg, int type)
+{
+	int snd;
+	struct iovec iov;
+	struct msghdr msgh;
+	struct cmsghdr *cmsg;
+	struct sockaddr_un dst;
+	struct mp_msg_internal m;
+	int fd_size = msg->num_fds * sizeof(int);
+	char control[CMSG_SPACE(fd_size)];
+
+	m.type = type;
+	memcpy(&m.msg, msg, sizeof(*msg));
+
+	memset(&dst, 0, sizeof(dst));
+	dst.sun_family = AF_UNIX;
+	snprintf(dst.sun_path, sizeof(dst.sun_path), "%s", dst_path);
+
+	memset(&msgh, 0, sizeof(msgh));
+	memset(control, 0, sizeof(control));
+
+	iov.iov_base = &m;
+	iov.iov_len = sizeof(m) - sizeof(msg->fds);
+
+	msgh.msg_name = &dst;
+	msgh.msg_namelen = sizeof(dst);
+	msgh.msg_iov = &iov;
+	msgh.msg_iovlen = 1;
+	msgh.msg_control = control;
+	msgh.msg_controllen = sizeof(control);
+
+	cmsg = CMSG_FIRSTHDR(&msgh);
+	cmsg->cmsg_len = CMSG_LEN(fd_size);
+	cmsg->cmsg_level = SOL_SOCKET;
+	cmsg->cmsg_type = SCM_RIGHTS;
+	memcpy(CMSG_DATA(cmsg), msg->fds, fd_size);
+
+	do {
+		snd = sendmsg(mp_fd, &msgh, 0);
+	} while (snd < 0 && errno == EINTR);
+
+	if (snd < 0) {
+		rte_errno = errno;
+		/* Check if it caused by peer process exits */
+		if (errno == ECONNREFUSED &&
+				rte_eal_process_type() == RTE_PROC_PRIMARY) {
+			unlink(dst_path);
+			return 0;
+		}
+		if (errno == ENOBUFS) {
+			RTE_LOG(ERR, EAL, "Peer cannot receive message %s\n",
+				dst_path);
+			return 0;
+		}
+		RTE_LOG(ERR, EAL, "failed to send to (%s) due to %s\n",
+			dst_path, strerror(errno));
+		return -1;
+	}
+
+	return 1;
+}
+
+static int
+mp_send(struct rte_mp_msg *msg, const char *peer, int type)
+{
+	int dir_fd, ret = 0;
+	DIR *mp_dir;
+	struct dirent *ent;
+
+	if (!peer && (rte_eal_process_type() == RTE_PROC_SECONDARY))
+		peer = eal_mp_socket_path();
+
+	if (peer) {
+		if (send_msg(peer, msg, type) < 0)
+			return -1;
+		else
+			return 0;
+	}
+
+	/* broadcast to all secondary processes */
+	mp_dir = opendir(mp_dir_path);
+	if (!mp_dir) {
+		RTE_LOG(ERR, EAL, "Unable to open directory %s\n",
+				mp_dir_path);
+		rte_errno = errno;
+		return -1;
+	}
+
+	dir_fd = dirfd(mp_dir);
+	/* lock the directory to prevent processes spinning up while we send */
+	if (flock(dir_fd, LOCK_EX)) {
+		RTE_LOG(ERR, EAL, "Unable to lock directory %s\n",
+			mp_dir_path);
+		rte_errno = errno;
+		closedir(mp_dir);
+		return -1;
+	}
+
+	while ((ent = readdir(mp_dir))) {
+		char path[PATH_MAX];
+
+		if (fnmatch(mp_filter, ent->d_name, 0) != 0)
+			continue;
+
+		snprintf(path, sizeof(path), "%s/%s", mp_dir_path,
+			 ent->d_name);
+		if (send_msg(path, msg, type) < 0)
+			ret = -1;
+	}
+	/* unlock the dir */
+	flock(dir_fd, LOCK_UN);
+
+	/* dir_fd automatically closed on closedir */
+	closedir(mp_dir);
+	return ret;
+}
+
 static int
 read_msg(struct mp_msg_internal *m, struct sockaddr_un *s)
 {
@@ -260,12 +385,13 @@ process_msg(struct mp_msg_internal *m, struct sockaddr_un *s)
 
 	RTE_LOG(DEBUG, EAL, "msg: %s\n", msg->name);
 
-	if (m->type == MP_REP) {
+	if (m->type == MP_REP || m->type == MP_IGN) {
 		pthread_mutex_lock(&sync_requests.lock);
 		sync_req = find_sync_request(s->sun_path, msg->name);
 		if (sync_req) {
 			memcpy(sync_req->reply, msg, sizeof(*msg));
-			sync_req->reply_received = 1;
+			/* -1 indicates that we've been asked to ignore */
+			sync_req->reply_received = m->type == MP_REP ? 1 : -1;
 			pthread_cond_signal(&sync_req->cond);
 		} else
 			RTE_LOG(ERR, EAL, "Drop mp reply: %s\n", msg->name);
@@ -279,10 +405,22 @@ process_msg(struct mp_msg_internal *m, struct sockaddr_un *s)
 		action = entry->action;
 	pthread_mutex_unlock(&mp_mutex_action);
 
-	if (!action)
-		RTE_LOG(ERR, EAL, "Cannot find action: %s\n", msg->name);
-	else if (action(msg, s->sun_path) < 0)
+	if (!action) {
+		if (m->type == MP_REQ && !internal_config.init_complete) {
+			/* if this is a request, and init is not yet complete,
+			 * and callback wasn't registered, we should tell the
+			 * requester to ignore our existence because we're not
+			 * yet ready to process this request.
+			 */
+			struct rte_mp_msg dummy = {0};
+			mp_send(&dummy, s->sun_path, MP_IGN);
+		} else {
+			RTE_LOG(ERR, EAL, "Cannot find action: %s\n",
+				msg->name);
+		}
+	} else if (action(msg, s->sun_path) < 0) {
 		RTE_LOG(ERR, EAL, "Fail to handle message: %s\n", msg->name);
+	}
 }
 
 static void *
@@ -419,130 +557,6 @@ rte_mp_channel_init(void)
 	return 0;
 }
 
-/**
- * Return -1, as fail to send message and it's caused by the local side.
- * Return 0, as fail to send message and it's caused by the remote side.
- * Return 1, as succeed to send message.
- *
- */
-static int
-send_msg(const char *dst_path, struct rte_mp_msg *msg, int type)
-{
-	int snd;
-	struct iovec iov;
-	struct msghdr msgh;
-	struct cmsghdr *cmsg;
-	struct sockaddr_un dst;
-	struct mp_msg_internal m;
-	int fd_size = msg->num_fds * sizeof(int);
-	char control[CMSG_SPACE(fd_size)];
-
-	m.type = type;
-	memcpy(&m.msg, msg, sizeof(*msg));
-
-	memset(&dst, 0, sizeof(dst));
-	dst.sun_family = AF_UNIX;
-	snprintf(dst.sun_path, sizeof(dst.sun_path), "%s", dst_path);
-
-	memset(&msgh, 0, sizeof(msgh));
-	memset(control, 0, sizeof(control));
-
-	iov.iov_base = &m;
-	iov.iov_len = sizeof(m) - sizeof(msg->fds);
-
-	msgh.msg_name = &dst;
-	msgh.msg_namelen = sizeof(dst);
-	msgh.msg_iov = &iov;
-	msgh.msg_iovlen = 1;
-	msgh.msg_control = control;
-	msgh.msg_controllen = sizeof(control);
-
-	cmsg = CMSG_FIRSTHDR(&msgh);
-	cmsg->cmsg_len = CMSG_LEN(fd_size);
-	cmsg->cmsg_level = SOL_SOCKET;
-	cmsg->cmsg_type = SCM_RIGHTS;
-	memcpy(CMSG_DATA(cmsg), msg->fds, fd_size);
-
-	do {
-		snd = sendmsg(mp_fd, &msgh, 0);
-	} while (snd < 0 && errno == EINTR);
-
-	if (snd < 0) {
-		rte_errno = errno;
-		/* Check if it caused by peer process exits */
-		if (errno == ECONNREFUSED &&
-				rte_eal_process_type() == RTE_PROC_PRIMARY) {
-			unlink(dst_path);
-			return 0;
-		}
-		if (errno == ENOBUFS) {
-			RTE_LOG(ERR, EAL, "Peer cannot receive message %s\n",
-				dst_path);
-			return 0;
-		}
-		RTE_LOG(ERR, EAL, "failed to send to (%s) due to %s\n",
-			dst_path, strerror(errno));
-		return -1;
-	}
-
-	return 1;
-}
-
-static int
-mp_send(struct rte_mp_msg *msg, const char *peer, int type)
-{
-	int dir_fd, ret = 0;
-	DIR *mp_dir;
-	struct dirent *ent;
-
-	if (!peer && (rte_eal_process_type() == RTE_PROC_SECONDARY))
-		peer = eal_mp_socket_path();
-
-	if (peer) {
-		if (send_msg(peer, msg, type) < 0)
-			return -1;
-		else
-			return 0;
-	}
-
-	/* broadcast to all secondary processes */
-	mp_dir = opendir(mp_dir_path);
-	if (!mp_dir) {
-		RTE_LOG(ERR, EAL, "Unable to open directory %s\n",
-				mp_dir_path);
-		rte_errno = errno;
-		return -1;
-	}
-
-	dir_fd = dirfd(mp_dir);
-	/* lock the directory to prevent processes spinning up while we send */
-	if (flock(dir_fd, LOCK_EX)) {
-		RTE_LOG(ERR, EAL, "Unable to lock directory %s\n",
-			mp_dir_path);
-		rte_errno = errno;
-		closedir(mp_dir);
-		return -1;
-	}
-
-	while ((ent = readdir(mp_dir))) {
-		char path[PATH_MAX];
-
-		if (fnmatch(mp_filter, ent->d_name, 0) != 0)
-			continue;
-
-		snprintf(path, sizeof(path), "%s/%s", mp_dir_path,
-			 ent->d_name);
-		if (send_msg(path, msg, type) < 0)
-			ret = -1;
-	}
-	/* unlock the dir */
-	flock(dir_fd, LOCK_UN);
-
-	/* dir_fd automatically closed on closedir */
-	closedir(mp_dir);
-	return ret;
-}
-
 static bool
 check_input(const struct rte_mp_msg *msg)
 {
@@ -631,6 +645,14 @@ mp_request_one(const char *dst, struct rte_mp_msg *req,
 		rte_errno = ETIMEDOUT;
 		return -1;
 	}
+	if (sync_req.reply_received == -1) {
+		RTE_LOG(DEBUG, EAL, "Asked to ignore response\n");
+		/* not receiving this message is not an error, so decrement
+		 * number of sent messages
+		 */
+		reply->nb_sent--;
+		return 0;
+	}
 
 	tmp = realloc(reply->msgs, sizeof(msg) * (reply->nb_received + 1));
 	if (!tmp) {
-- 
2.7.4