1 files changed, 13 insertions, 3 deletions
diff --git a/otherlibs/systhreads/st_stubs.c b/otherlibs/systhreads/st_stubs.c
index c751ffbcf1..db38b0168d 100644
--- a/otherlibs/systhreads/st_stubs.c
+++ b/otherlibs/systhreads/st_stubs.c
@@ -737,9 +737,19 @@ CAMLprim value caml_thread_exit(value unit)   /* ML */
 CAMLprim value caml_thread_yield(value unit)        /* ML */
 {
   if (st_masterlock_waiters(&caml_master_lock) == 0) return Val_unit;
-  caml_enter_blocking_section();
-  st_thread_yield();
-  caml_leave_blocking_section();
+
+  /* Do all the parts of a blocking section enter/leave except lock
+     manipulation, which we'll do more efficiently in st_thread_yield. (Since
+     our blocking section doesn't contain anything interesting, don't bother
+     with saving errno.)
+  */
+  caml_process_pending_signals();
+  caml_thread_save_runtime_state();
+  st_thread_yield(&caml_master_lock);
+  curr_thread = st_tls_get(thread_descriptor_key);
+  caml_thread_restore_runtime_state();
+  caml_process_pending_signals();
+
   return Val_unit;
 }