rcutorture: Aggressive forward-progress tests shouldn't block shutdown

The more aggressive forward-progress tests can interfere with rcutorture
shutdown, resulting in false-positive diagnostics.  This commit therefore
ends any such tests 30 seconds prior to shutdown.

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

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index c44e5307afcce4b2f24393b0feca7c0fe9732c81..b22947324423b87ff76e79777ed1ba54369b381b 100644 (file)
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -161,6 +161,7 @@ static atomic_long_t n_rcu_torture_timers;
 static long n_barrier_attempts;
 static long n_barrier_successes; /* did rcu_barrier test succeed? */
 static struct list_head rcu_torture_removed;
+static unsigned long shutdown_jiffies;
 
 static int rcu_torture_writer_state;
 #define RTWS_FIXED_DELAY       0
@@ -228,6 +229,15 @@ static u64 notrace rcu_trace_clock_local(void)
 }
 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 
+/*
+ * Stop aggressive CPU-hog tests a bit before the end of the test in order
+ * to avoid interfering with test shutdown.
+ */
+static bool shutdown_time_arrived(void)
+{
+       return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
+}
+
 static unsigned long boost_starttime;  /* jiffies of next boost test start. */
 static DEFINE_MUTEX(boost_mutex);      /* protect setting boost_starttime */
                                        /*  and boost task create/destroy. */
@@ -1787,6 +1797,7 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
        WRITE_ONCE(rcu_fwd_startat, jiffies);
        stopat = rcu_fwd_startat + dur;
        while (time_before(jiffies, stopat) &&
+              !shutdown_time_arrived() &&
               !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
                idx = cur_ops->readlock();
                udelay(10);
@@ -1796,6 +1807,7 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
        }
        (*tested_tries)++;
        if (!time_before(jiffies, stopat) &&
+           !shutdown_time_arrived() &&
            !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
                (*tested)++;
                cver = READ_ONCE(rcu_torture_current_version) - cver;
@@ -1854,6 +1866,7 @@ static void rcu_torture_fwd_prog_cr(void)
        gps = cur_ops->get_gp_seq();
        rcu_launder_gp_seq_start = gps;
        while (time_before(jiffies, stopat) &&
+              !shutdown_time_arrived() &&
               !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
                rfcp = READ_ONCE(rcu_fwd_cb_head);
                rfcpn = NULL;
@@ -1886,7 +1899,8 @@ static void rcu_torture_fwd_prog_cr(void)
        cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
        (void)rcu_torture_fwd_prog_cbfree();
 
-       if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop)) {
+       if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
+           !shutdown_time_arrived()) {
                WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
                pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n",
                         __func__,
@@ -2467,6 +2481,7 @@ rcu_torture_init(void)
                        goto unwind;
                rcutor_hp = firsterr;
        }
+       shutdown_jiffies = jiffies + shutdown_secs * HZ;
        firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
        if (firsterr)
                goto unwind;