From d4d82fc3ab9623b40a97e6d6d4624189ec7674bc Mon Sep 17 00:00:00 2001
From: Jim Harris <james.r.harris@intel.com>
Date: Tue, 11 Oct 2016 11:20:49 -0700
Subject: [PATCH] event: directly add poller when adding to current core

This is required since pollers are now directly removed
(rather than scheduling an event) when the unregister call
is made on the poller's lcore.

Without this change, if a poller is registered then
immediately unregistered, the unregistration will seg
fault since the event adding the poller has not executed
yet.

Also add a test case that exhibits the sequence of events
described in this commit message.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: I5c6ba0ee224ac1f8f3ebb8e7571714e718bd42db
---
 lib/event/reactor.c              | 36 ++++++++++++++++++++++++--------
 test/lib/event/reactor/reactor.c |  9 ++++++++
 2 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/lib/event/reactor.c b/lib/event/reactor.c
index 4864d9e84..80dcef23c 100644
--- a/lib/event/reactor.c
+++ b/lib/event/reactor.c
@@ -661,12 +661,9 @@ spdk_reactors_fini(void)
 }
 
 static void
-_spdk_event_add_poller(spdk_event_t event)
+_spdk_poller_register(struct spdk_reactor *reactor, struct spdk_poller *poller,
+		      struct spdk_event *next)
 {
-	struct spdk_reactor *reactor = spdk_event_get_arg1(event);
-	struct spdk_poller *poller = spdk_event_get_arg2(event);
-	struct spdk_event *next = spdk_event_get_next(event);
-
 	if (poller->period_ticks) {
 		spdk_poller_insert_timer(reactor, poller, spdk_get_ticks());
 	} else {
@@ -678,13 +675,22 @@ _spdk_event_add_poller(spdk_event_t event)
 	}
 }
 
+static void
+_spdk_event_add_poller(spdk_event_t event)
+{
+	struct spdk_reactor *reactor = spdk_event_get_arg1(event);
+	struct spdk_poller *poller = spdk_event_get_arg2(event);
+	struct spdk_event *next = spdk_event_get_next(event);
+
+	_spdk_poller_register(reactor, poller, next);
+}
+
 void
 spdk_poller_register(struct spdk_poller **ppoller, spdk_poller_fn fn, void *arg,
 		     uint32_t lcore, struct spdk_event *complete, uint64_t period_microseconds)
 {
 	struct spdk_poller *poller;
 	struct spdk_reactor *reactor;
-	struct spdk_event *event;
 
 	poller = calloc(1, sizeof(*poller));
 	if (poller == NULL) {
@@ -709,10 +715,22 @@ spdk_poller_register(struct spdk_poller **ppoller, spdk_poller_fn fn, void *arg,
 	}
 
 	*ppoller = poller;
-
 	reactor = spdk_reactor_get(lcore);
-	event = spdk_event_allocate(lcore, _spdk_event_add_poller, reactor, poller, complete);
-	spdk_event_call(event);
+
+	if (lcore == spdk_app_get_current_core()) {
+		/*
+		 * The poller is registered to run on the current core, so call the add function
+		 * directly.
+		 */
+		_spdk_poller_register(reactor, poller, complete);
+	} else {
+		/*
+		 * The poller is registered to run on a different core.
+		 * Schedule an event to run on the poller's core that will add the poller.
+		 */
+		spdk_event_call(spdk_event_allocate(lcore, _spdk_event_add_poller, reactor, poller,
+						    complete));
+	}
 }
 
 static void
diff --git a/test/lib/event/reactor/reactor.c b/test/lib/event/reactor/reactor.c
index a98837924..547896d32 100644
--- a/test/lib/event/reactor/reactor.c
+++ b/test/lib/event/reactor/reactor.c
@@ -44,6 +44,7 @@ static struct spdk_poller *poller_100ms;
 static struct spdk_poller *poller_250ms;
 static struct spdk_poller *poller_500ms;
 static struct spdk_poller *poller_oneshot;
+static struct spdk_poller *poller_unregister;
 
 static void
 test_end(void *arg)
@@ -67,6 +68,11 @@ oneshot(void *arg)
 	spdk_poller_unregister(&poller_oneshot, NULL);
 }
 
+static void
+nop(void *arg)
+{
+}
+
 static void
 test_start(spdk_event_t evt)
 {
@@ -79,6 +85,9 @@ test_start(spdk_event_t evt)
 	spdk_poller_register(&poller_250ms, tick, (void *)250, 0, NULL, 250000);
 	spdk_poller_register(&poller_500ms, tick, (void *)500, 0, NULL, 500000);
 	spdk_poller_register(&poller_oneshot, oneshot, NULL, 0, NULL, 0);
+
+	spdk_poller_register(&poller_unregister, nop, NULL, 0, NULL, 0);
+	spdk_poller_unregister(&poller_unregister, NULL);
 }
 
 static void