5281 incorrect realtime signal delivery

*** 18,27 ****
--- 18,28 ----
   *
   * CDDL HEADER END
   */
  
  /*
+  * Copyright 2014 Ryan Zezeski.  All rights reserved.
   * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
  #include "lint.h"
*** 68,77 ****
--- 69,79 ----
   * Common code for calling the user-specified signal handler.
   */
  void
  call_user_handler(int sig, siginfo_t *sip, ucontext_t *ucp)
  {
+         int i;
          ulwp_t *self = curthread;
          uberdata_t *udp = self->ul_uberdata;
          struct sigaction uact;
          volatile struct sigaction *sap;
  
*** 153,162 ****
--- 155,178 ----
                  /* the signal mask at the previous level */
                  sigorset(&uact.sa_mask, &ucp->uc_sigmask);
          }
          if (!(uact.sa_flags & SA_NODEFER))      /* add current signal */
                  (void) sigaddset(&uact.sa_mask, sig);
+ 
+         /*
+          * Enforce the proper order for realtime signals.  Lower signals
+          * have higher priority and multiple instances of the same signal
+          * must arrive in FIFO order (NODEFER does not apply).
+          *
+          * See section 2.4.2 of POSIX.
+          */
+         if ((sig >= SIGRTMIN) && (sig <= SIGRTMAX)) {
+                 for (i = sig; i <= SIGRTMAX; i++) {
+                         (void) sigaddset(&uact.sa_mask, i);
+                 }
+         }
+ 
          self->ul_sigmask = uact.sa_mask;
          self->ul_siglink = ucp;
          (void) __lwp_sigmask(SIG_SETMASK, &uact.sa_mask);
  
          /*