[dpdk-dev] [PATCH v6 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.

Since it is not possible for primary process to receive any messages
during initialization, this change in practice only applies to
secondary processes.

Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
Acked-by: Jianfeng Tan <jianfeng.tan at intel.com>
---

Notes:
    v6: - clang fix
        - forward declare mp_send instead of code move
        - clarify commit message
    v5: add this patch
    
    No changes in mp_send and send_msg - just code move.

 lib/librte_eal/common/eal_common_proc.c | 38 ++++++++++++++++++++++++++++-----
 1 file changed, 33 insertions(+), 5 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_proc.c b/lib/librte_eal/common/eal_common_proc.c
index fe27d68..4131b67 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 {
@@ -78,6 +79,11 @@ static struct {
 	.lock = PTHREAD_MUTEX_INITIALIZER
 };
 
+/* forward declarations */
+static int
+mp_send(struct rte_mp_msg *msg, const char *peer, int type);
+
+
 static struct sync_request *
 find_sync_request(const char *dst, const char *act_name)
 {
@@ -260,12 +266,13 @@ 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 +286,23 @@ 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;
+			memset(&dummy, 0, sizeof(dummy));
+			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 *
@@ -631,6 +651,14 @@ 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