Limit use of sched_yield for sync in tests (#1407)

bin/utest/fork.c

@@ -32,13 +32,21 @@ static void sigchld_handler(int signo) {
 
 TEST_ADD(fork_signal, 0) {
   xsignal(SIGCHLD, sigchld_handler);
+
+  sigset_t mask, saved;
+  sigemptyset(&mask);
+  sigaddset(&mask, SIGCHLD);
+  xsigprocmask(SIG_BLOCK, &mask, &saved);
+
   pid_t n = xfork();
   if (n == 0)
     exit(0);
 
   /* Wait for the child to get reaped by signal handler. */
   while (!done)
-    sched_yield();
+    sigsuspend(&saved);
+
+  xsigprocmask(SIG_UNBLOCK, &mask, NULL);
   xsignal(SIGCHLD, SIG_DFL);
   return 0;
 }

bin/utest/mmap.c

@@ -125,16 +125,10 @@ TEST_ADD(munmap, 0) {
   return 0;
 }
 
-static volatile int sigcont_handled = 0;
-
-static void sigcont_handler(int signo) {
-  debug("sigcont handled!");
-  sigcont_handled = 1;
-}
-
 TEST_ADD(mmap_private, 0) {
   size_t pgsz = getpagesize();
-  xsignal(SIGCONT, sigcont_handler);
+
+  signal_setup(SIGUSR1);
 
   /* mmap & munmap one page */
   char *addr = mmap_anon_prw(NULL, pgsz);
@@ -153,26 +147,24 @@ TEST_ADD(mmap_private, 0) {
     debug("Child written: '%s'", addr);
 
     /* Wait for parent to check and modify its memory. */
-    xkill(getppid(), SIGCONT);
-    while (!sigcont_handled)
-      sched_yield();
+    xkill(getppid(), SIGUSR1);
+    wait_for_signal(SIGUSR1);
 
     debug("Child read again: '%s'", addr);
     string_eq(addr, "child");
     exit(0);
   }
 
   /* Wait for child to check and modify its memory. */
-  while (!sigcont_handled)
-    sched_yield();
+  wait_for_signal(SIGUSR1);
 
   debug("Parent read: '%s'", addr);
   /* Check and modify. */
   string_eq(addr, "parent");
   strcpy(addr, "parent again");
 
   /* Resume child. */
-  xkill(pid, SIGCONT);
+  xkill(pid, SIGUSR1);
 
   wait_child_finished(pid);
   return 0;

bin/utest/pgrp.c

@@ -51,13 +51,14 @@ TEST_ADD(setpgid_leader, 0) {
     /* Can't change pgrp of session leader. */
     assert(setpgid(0, 0));
 
+    xkill(getppid(), SIGUSR1);
     wait_for_signal(SIGUSR1);
     return 0;
   }
 
   /* Wait until child becomes session leader. */
-  while (getsid(cpid) != cpid)
-    sched_yield();
+  wait_for_signal(SIGUSR1);
+  assert(getsid(cpid) == cpid);
 
   /* Can't change pgrp of session leader. */
   assert(setpgid(cpid, getpgid(0)));
@@ -69,13 +70,17 @@ TEST_ADD(setpgid_leader, 0) {
 }
 
 TEST_ADD(setpgid_child, 0) {
-  signal_setup(SIGUSR1);
+  signal_setup(SIGUSR1); /* child 1 */
+  signal_setup(SIGUSR2); /* child 2 */
 
   pid_t cpid1 = xfork();
   if (cpid1 == 0) {
     /* Become session leader. */
     assert(setsid() == getpid());
 
+    /* Signal readiness to parent. */
+    xkill(getppid(), SIGUSR1);
+
     /* Wait until our parent gives a signal to exit. */
     wait_for_signal(SIGUSR1);
     return 0;
@@ -84,23 +89,23 @@ TEST_ADD(setpgid_child, 0) {
   pid_t cpid2 = xfork();
   if (cpid2 == 0) {
     /* Signal readiness to parent. */
-    xkill(getppid(), SIGUSR1);
+    xkill(getppid(), SIGUSR2);
 
     /* A child should not be able to change its parent's
      * process group. */
     assert(setpgid(getppid(), 0));
 
     /* Wait until our parent gives a signal to exit. */
-    wait_for_signal(SIGUSR1);
+    wait_for_signal(SIGUSR2);
     return 0;
   }
 
   /* Wait for child 1 to become session leader. */
-  while (getsid(cpid1) != cpid1)
-    sched_yield();
+  wait_for_signal(SIGUSR1);
+  assert(getsid(cpid1) == cpid1);
 
   /* Wait until child 2 is ready. */
-  wait_for_signal(SIGUSR1);
+  wait_for_signal(SIGUSR2);
 
   /* Move child 2 into its own process group. */
   assert(!setpgid(cpid2, cpid2));
@@ -115,7 +120,7 @@ TEST_ADD(setpgid_child, 0) {
   assert(getpgid(cpid2) == getpgid(0));
 
   xkill(cpid1, SIGUSR1);
-  xkill(cpid2, SIGUSR1);
+  xkill(cpid2, SIGUSR2);
 
   wait_child_finished(cpid1);
   wait_child_finished(cpid2);
@@ -277,11 +282,9 @@ TEST_ADD(pgrp_orphan, 0) {
   return 0;
 }
 
-static volatile pid_t parent_sid;
-
 TEST_ADD(session_basic, 0) {
   signal_setup(SIGUSR1);
-  parent_sid = getsid(getpid());
+  pid_t parent_sid = getsid(getpid());
   assert(parent_sid != -1);
   pid_t cpid = xfork();
   if (cpid == 0) {
@@ -292,6 +295,7 @@ TEST_ADD(session_basic, 0) {
     assert(getsid(ppid) == parent_sid);
     /* Create a session. This should always succeed. */
     assert(setsid() == cpid);
+    xkill(ppid, SIGUSR1);
     assert(getsid(0) == cpid);
     assert(getsid(ppid) == parent_sid);
     /* Creating a session when we're already a leader should fail. */
@@ -303,11 +307,8 @@ TEST_ADD(session_basic, 0) {
     return 0;
   }
 
-  pid_t child_sid;
-  while ((child_sid = getsid(cpid)) != cpid) {
-    assert(child_sid == parent_sid);
-    sched_yield();
-  }
+  wait_for_signal(SIGUSR1);
+  assert(getsid(cpid) == cpid);
 
   xkill(cpid, SIGUSR1);
   wait_child_finished(cpid);

bin/utest/signal.c

@@ -47,9 +47,8 @@ TEST_ADD(signal_send, 0) {
   pid_t pid = xfork();
   if (pid == 0) {
     debug("This is child (mypid = %d)", getpid());
-    /* Wait for signal. */
-    while (1)
-      sched_yield();
+    pause(); /* Wait for signal. */
+    exit(0);
   }
 
   debug("This is parent (childpid = %d, mypid = %d)", pid, getpid());

bin/utest/util.c

@@ -45,7 +45,7 @@ void signal_setup(int signo) {
   sigset_t mask;
   sigemptyset(&mask);
   sigaddset(&mask, signo);
-  assert(sigprocmask(SIG_BLOCK, &mask, NULL) == 0);
+  xsigprocmask(SIG_BLOCK, &mask, NULL);
 }
 
 void wait_for_signal(int signo) {