Merge branch 'lukas/erts/fix_scheduler_suspend/ERL-94/PR-978/OTP-13425'

* lukas/erts/fix_scheduler_suspend/ERL-94/PR-978/OTP-13425:
  erts: Fix install of suspend handler

Conflicts:
	erts/emulator/sys/unix/erl_unix_sys.h
	erts/emulator/sys/unix/sys.c

2 files changed, 15 insertions, 6 deletions

diff --git a/erts/emulator/sys/unix/erl_unix_sys.h b/erts/emulator/sys/unix/erl_unix_sys.h
index 8b1822ca9f..e217c38ca9 100644
--- a/erts/emulator/sys/unix/erl_unix_sys.h
+++ b/erts/emulator/sys/unix/erl_unix_sys.h
@@ -321,6 +321,7 @@ typedef void (*SIGFUNC)(int);
 extern SIGFUNC sys_signal(int, SIGFUNC);
 extern void sys_sigrelease(int);
 extern void sys_sigblock(int);
+extern void sys_init_suspend_handler(void);
 
 /*
  * Handling of floating point exceptions.
diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
index 0a18e54389..4f992d3caf 100644
--- a/erts/emulator/sys/unix/sys.c
+++ b/erts/emulator/sys/unix/sys.c
@@ -121,8 +121,10 @@ erts_smp_atomic_t sys_misc_mem_sz;
 static void smp_sig_notify(char c);
 static int sig_notify_fds[2] = {-1, -1};
 
+#if !defined(ETHR_UNUSABLE_SIGUSRX) && defined(ERTS_THR_HAVE_SIG_FUNCS)
 static int sig_suspend_fds[2] = {-1, -1};
 #define ERTS_SYS_SUSPEND_SIGNAL SIGUSR2
+#endif
 
 #endif
 
@@ -678,7 +680,7 @@ sigusr1_exit(void)
 
 #else
 
-#ifdef ERTS_SMP
+#ifdef ERTS_SYS_SUSPEND_SIGNAL
 void
 sys_thr_suspend(erts_tid_t tid) {
     erts_thr_kill(tid, ERTS_SYS_SUSPEND_SIGNAL);
@@ -706,7 +708,7 @@ static RETSIGTYPE user_signal1(int signum)
 #endif
 }
 
-#ifdef ERTS_SMP
+#ifdef ERTS_SYS_SUSPEND_SIGNAL
 #if (defined(SIG_SIGSET) || defined(SIG_SIGNAL))
 static RETSIGTYPE suspend_signal(void)
 #else
@@ -719,7 +721,7 @@ static RETSIGTYPE suspend_signal(int signum)
      res = read(sig_suspend_fds[0], buf, sizeof(int));
    } while (res < 0 && errno == EINTR);
 }
-#endif /* #ifdef ERTS_SMP */
+#endif /* #ifdef ERTS_SYS_SUSPEND_SIGNAL */
 
 #endif /* #ifndef ETHR_UNUSABLE_SIGUSRX */
 
@@ -772,13 +774,17 @@ void init_break_handler(void)
    sys_signal(SIGINT, request_break);
 #ifndef ETHR_UNUSABLE_SIGUSRX
    sys_signal(SIGUSR1, user_signal1);
-#ifdef ERTS_SMP
-   sys_signal(ERTS_SYS_SUSPEND_SIGNAL, suspend_signal);
-#endif /* #ifdef ERTS_SMP */
 #endif /* #ifndef ETHR_UNUSABLE_SIGUSRX */
    sys_signal(SIGQUIT, do_quit);
 }
 
+void sys_init_suspend_handler(void)
+{
+#ifdef ERTS_SYS_SUSPEND_SIGNAL
+   sys_signal(ERTS_SYS_SUSPEND_SIGNAL, suspend_signal);
+#endif
+}
+
 int sys_max_files(void)
 {
    return(max_files);
@@ -1323,12 +1329,14 @@ init_smp_sig_notify(void)
 
 static void
 init_smp_sig_suspend(void) {
+#ifdef ERTS_SYS_SUSPEND_SIGNAL
   if (pipe(sig_suspend_fds) < 0) {
     erts_exit(ERTS_ABORT_EXIT,
 	     "Failed to create sig_suspend pipe: %s (%d)\n",
 	     erl_errno_id(errno),
 	     errno);
   }
+#endif
 }
 
 #ifdef __DARWIN__