1 #include <u.h>
2 #include <signal.h>
3 #include <libc.h>
4 
5 #define DBG 0
6 
7 static void
8 ign(int x)
9 {
10 	USED(x);
11 }
12 
13 void /*__attribute__((constructor))*/
14 ignusr1(int restart)
15 {
16 	struct sigaction sa;
17 
18 	memset(&sa, 0, sizeof sa);
19 	sa.sa_handler = ign;
20 	sigemptyset(&sa.sa_mask);
21 	sigaddset(&sa.sa_mask, SIGUSR1);
22 	if(restart)
23 		sa.sa_flags = SA_RESTART;
24 	sigaction(SIGUSR1, &sa, nil);
25 }
26 
27 void
28 _procsleep(_Procrend *r)
29 {
30 	sigset_t mask;
31 
32 	/*
33 	 * Go to sleep.
34 	 *
35 	 * Block USR1, set the handler to interrupt system calls,
36 	 * unlock the vouslock so our waker can wake us,
37 	 * and then suspend.
38 	 */
39 	r->asleep = 1;
40 	r->pid = getpid();
41 
42 	sigprocmask(SIG_SETMASK, nil, &mask);
43 	sigaddset(&mask, SIGUSR1);
44 	sigprocmask(SIG_SETMASK, &mask, nil);
45 	ignusr1(0);
46 	unlock(r->l);
47 	sigdelset(&mask, SIGUSR1);
48 	sigsuspend(&mask);
49 
50 	/*
51 	 * We're awake.  Make USR1 not interrupt system calls.
52 	 */
53 	ignusr1(1);
54 	assert(r->asleep == 0);
55 	lock(r->l);
56 }
57 
58 void
59 _procwakeup(_Procrend *r)
60 {
61 	r->asleep = 0;
62 	assert(r->pid >= 1);
63 	kill(r->pid, SIGUSR1);
64 }