From 0c4c9d78b539ae7fcbfce2b4372811bb6b4a19d8 Mon Sep 17 00:00:00 2001
From: Yash Tibrewal <yashkt@google.com>
Date: Thu, 5 Apr 2018 19:39:10 -0700
Subject: [PATCH] poll-cv fix for zero timeout

---
 src/core/lib/iomgr/ev_poll_posix.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/core/lib/iomgr/ev_poll_posix.cc b/src/core/lib/iomgr/ev_poll_posix.cc
index 2e375b40226..d9aba9b6a3b 100644
--- a/src/core/lib/iomgr/ev_poll_posix.cc
+++ b/src/core/lib/iomgr/ev_poll_posix.cc
@@ -1530,6 +1530,12 @@ static void run_poll(void* args) {
 
 // This function overrides poll() to handle condition variable wakeup fds
 static int cvfd_poll(struct pollfd* fds, nfds_t nfds, int timeout) {
+  if (timeout == 0) {
+    // Don't bother using background threads for polling if timeout is 0,
+    // poll-cv might not wait for a poll to return otherwise.
+    // https://github.com/grpc/grpc/issues/13298
+    return poll(fds, nfds, 0);
+  }
   unsigned int i;
   int res, idx;
   grpc_cv_node* pollcv;