rcu: Make rcu_torture_fqs() exit loops at end of test

The rcu_torture_fqs() function can prevent the rcutorture tests from
completing, resulting in a hang.  This commit therefore ensures that
rcu_torture_fqs() will exit its inner loops at the end of the test,
and also applies the newish ULONG_CMP_LT() macro to time comparisons.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index ade7771b208ab633b5ab3647caf33ab16b0b8b22..2431d576e9cabbd436d0b1a29c2cae04ffc245b0 100644 (file)
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -741,7 +741,7 @@ static int rcu_torture_boost(void *arg)
        do {
                /* Wait for the next test interval. */
                oldstarttime = boost_starttime;
-               while (jiffies - oldstarttime > ULONG_MAX / 2) {
+               while (ULONG_CMP_LT(jiffies, oldstarttime)) {
                        schedule_timeout_uninterruptible(1);
                        rcu_stutter_wait("rcu_torture_boost");
                        if (kthread_should_stop() ||
@@ -752,7 +752,7 @@ static int rcu_torture_boost(void *arg)
                /* Do one boost-test interval. */
                endtime = oldstarttime + test_boost_duration * HZ;
                call_rcu_time = jiffies;
-               while (jiffies - endtime > ULONG_MAX / 2) {
+               while (ULONG_CMP_LT(jiffies, endtime)) {
                        /* If we don't have a callback in flight, post one. */
                        if (!rbi.inflight) {
                                smp_mb(); /* RCU core before ->inflight = 1. */
@@ -818,11 +818,13 @@ rcu_torture_fqs(void *arg)
        VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
        do {
                fqs_resume_time = jiffies + fqs_stutter * HZ;
-               while (jiffies - fqs_resume_time > LONG_MAX) {
+               while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
+                      !kthread_should_stop()) {
                        schedule_timeout_interruptible(1);
                }
                fqs_burst_remaining = fqs_duration;
-               while (fqs_burst_remaining > 0) {
+               while (fqs_burst_remaining > 0 &&
+                      !kthread_should_stop()) {
                        cur_ops->fqs();
                        udelay(fqs_holdoff);
                        fqs_burst_remaining -= fqs_holdoff;