[newlib-cygwin] Cygwin: fhandler_fifo::take_ownership: don't set event unnecessarily

[Ken Brown <kbrown@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=a4dc0eb15c534396b199b6aa350475b62bae32d5

commit a4dc0eb15c534396b199b6aa350475b62bae32d5
Author: Ken Brown <kbrown@cornell.edu>
Date:   Sun Jul 12 18:11:38 2020 -0400

    Cygwin: fhandler_fifo::take_ownership: don't set event unnecessarily
    
    Don't set update_needed_evt if there's currently no owner.  This will
    cause unnecessary churn once I'm the owner and am listening for
    connections.

Diff:
---
 winsup/cygwin/fhandler_fifo.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index b6e172ddc..fd1695f40 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -1186,8 +1186,11 @@ fhandler_fifo::take_ownership ()
       return;
     }
   set_pending_owner (me);
+  /* Wake up my fifo_reader_thread. */
   owner_needed ();
-  SetEvent (update_needed_evt);
+  if (get_owner ())
+    /* Wake up owner's fifo_reader_thread. */
+    SetEvent (update_needed_evt);
   owner_unlock ();
   /* The reader threads should now do the transfer.  */
   WaitForSingleObject (owner_found_evt, INFINITE);