vcl: support for eventfd mq signaling

- support eventfd based mq signaling. Based on configuration, vcl
epoll/select can use either condvars or epoll on mq eventfds.
- add vcl support for memfd segments
- vpp explicitly registers cut-through segments with apps/vcl
- if using eventfd, make ldp allow one call to libc_epoll_create. Needed
for the message queue epfd
- update svm_queue_t to allow blocking calls with eventfd signaling.

Change-Id: I064151ac370bbe29bb16c968bf4e3659c8286bea
Signed-off-by: Florin Coras <fcoras@cisco.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/svm/queue.h b/src/svm/queue.h
index 75e63a49319..3e8031e897b 100644
--- a/src/svm/queue.h
+++ b/src/svm/queue.h
@@ -82,6 +82,24 @@ int svm_queue_add_nolock (svm_queue_t * q, u8 * elem);
 int svm_queue_sub_raw (svm_queue_t * q, u8 * elem);
 
 /**
+ * Wait for queue event
+ *
+ * Must be called with mutex held.
+ */
+void svm_queue_wait (svm_queue_t * q);
+
+/**
+ * Timed wait for queue event
+ *
+ * Must be called with mutex held.
+ *
+ * @param q		svm queue
+ * @param timeout	time in seconds
+ * @return 		0 on success, ETIMEDOUT on timeout or an error
+ */
+int svm_queue_timedwait (svm_queue_t * q, double timeout);
+
+/**
  * Add element to queue with mutex held
  * @param q		queue
  * @param elem		pointer element data to add