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, 33 insertions, 0 deletions

diff --git a/src/svm/message_queue.c b/src/svm/message_queue.c
index e97cab898e8..d6a77e783e3 100644
--- a/src/svm/message_queue.c
+++ b/src/svm/message_queue.c
@@ -15,6 +15,7 @@
 
 #include <svm/message_queue.h>
 #include <vppinfra/mem.h>
+#include <sys/eventfd.h>
 
 static inline svm_msg_q_ring_t *
 svm_msg_q_ring_inline (svm_msg_q_t * mq, u32 ring_index)
@@ -235,6 +236,38 @@ svm_msg_q_sub_w_lock (svm_msg_q_t * mq, svm_msg_q_msg_t * msg)
   svm_queue_sub_raw (mq->q, (u8 *) msg);
 }
 
+void
+svm_msg_q_set_consumer_eventfd (svm_msg_q_t * mq, int fd)
+{
+  mq->q->consumer_evtfd = fd;
+}
+
+void
+svm_msg_q_set_producer_eventfd (svm_msg_q_t * mq, int fd)
+{
+  mq->q->producer_evtfd = fd;
+}
+
+int
+svm_msg_q_alloc_consumer_eventfd (svm_msg_q_t * mq)
+{
+  int fd;
+  if ((fd = eventfd (0, EFD_NONBLOCK)) < 0)
+    return -1;
+  svm_msg_q_set_consumer_eventfd (mq, fd);
+  return 0;
+}
+
+int
+svm_msg_q_alloc_producer_eventfd (svm_msg_q_t * mq)
+{
+  int fd;
+  if ((fd = eventfd (0, EFD_NONBLOCK)) < 0)
+    return -1;
+  svm_msg_q_set_producer_eventfd (mq, fd);
+  return 0;
+}
+
 /*
  * fd.io coding-style-patch-verification: ON
  *