Merge pull request #23236 from tpetkov-VMW/fix-grpc_is_epollexclusive_available

Fix false positive in grpc_is_epollexclusive_available on ESXi

src/core/lib/iomgr/is_epollexclusive_available.cc

@@ -93,6 +93,20 @@ bool grpc_is_epollexclusive_available(void) {
     close(evfd);
     return false;
   }
+  // Check that EPOLLEXCLUSIVE is supported at all.
+  ev.events = static_cast<uint32_t>(EPOLLET | EPOLLIN | EPOLLEXCLUSIVE);
+  if (epoll_ctl(fd, EPOLL_CTL_ADD, evfd, &ev) != 0) {
+    if (!logged_why_not) {
+      gpr_log(GPR_DEBUG,
+              "epoll_ctl with EPOLLEXCLUSIVE failed with error: "
+              "%d. Not using epollex polling engine.",
+              errno);
+      logged_why_not = true;
+    }
+    close(fd);
+    close(evfd);
+    return false;
+  }
   close(evfd);
   close(fd);
   return true;