From: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
Currently, rcutorture runs between 25% and 50% of grace periods as
expedited grace periods. This means that on large configurations,
there are expected to be a number of expedited grace periods executing
concurrently with each normal grace period. Now that normal grace periods
can be assisted by expedited grace periods, rcutorture would be unable to
detect a bug that prevented normal grace periods from completing if there
was no expedited grace period helping it.
This commit therefore alternates 30-second phases that run expedited
grace periods and 30-second phases that do not, so that this sort of
bug will provoke an RCU CPU stall warning.
Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
---
kernel/rcu/rcutorture.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 59aa76b4460e..c62c1c34d73c 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -54,6 +54,11 @@
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paul...@us.ibm.com> and Josh Triplett
<j...@joshtriplett.org>");
+#ifdef CONFIG_RCU_CPU_STALL_TIMEOUT
+#define NOEXP_SECS_DEFAULT (CONFIG_RCU_CPU_STALL_TIMEOUT + 10)
+#else /* #ifdef CONFIG_RCU_CPU_STALL_TIMEOUT */
+#define NOEXP_SECS_DEFAULT 30
+#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_TIMEOUT */
torture_param(int, cbflood_inter_holdoff, HZ,
"Holdoff between floods (jiffies)");
@@ -75,6 +80,8 @@ torture_param(int, irqreader, 1, "Allow RCU readers from irq
handlers");
torture_param(int, n_barrier_cbs, 0,
"# of callbacks/kthreads for barrier testing");
torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
+torture_param(int, noexp_secs, NOEXP_SECS_DEFAULT,
+ "Time to suppress/enable expedited GPs (s), 0 to disable");
torture_param(int, nreaders, -1, "Number of RCU reader threads");
torture_param(int, object_debug, 0,
"Enable debug-object double call_rcu() testing");
@@ -192,6 +199,8 @@ static u64 notrace rcu_trace_clock_local(void)
}
#endif /* #else #ifdef CONFIG_RCU_TRACE */
+static unsigned long rcutorture_noexp;
+
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. */
@@ -894,6 +903,8 @@ rcu_torture_writer(void *arg)
bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
bool gp_sync1 = gp_sync;
int i;
+ int noexp_jiffies = noexp_secs * HZ;
+ unsigned long noexp_jiffies_next = jiffies - 1;
struct rcu_torture *rp;
struct rcu_torture *old_rp;
static DEFINE_TORTURE_RANDOM(rand);
@@ -942,6 +953,10 @@ rcu_torture_writer(void *arg)
do {
rcu_torture_writer_state = RTWS_FIXED_DELAY;
schedule_timeout_uninterruptible(1);
+ if (time_after(jiffies, noexp_jiffies_next)) {
+ rcutorture_noexp = jiffies + noexp_jiffies;
+ noexp_jiffies_next = rcutorture_noexp + noexp_jiffies;
+ }
rp = rcu_torture_alloc();
if (rp == NULL)
continue;
@@ -966,6 +981,9 @@ rcu_torture_writer(void *arg)
cur_ops->deferred_free(old_rp);
break;
case RTWS_EXP_SYNC:
+ if (time_before(jiffies, rcutorture_noexp) &&
+ cur_ops->sync && gp_sync1)
+ goto noexp;
rcu_torture_writer_state = RTWS_EXP_SYNC;
cur_ops->exp_sync();
rcu_torture_pipe_update(old_rp);
@@ -982,6 +1000,7 @@ rcu_torture_writer(void *arg)
rcu_torture_pipe_update(old_rp);
break;
case RTWS_SYNC:
+noexp:
rcu_torture_writer_state = RTWS_SYNC;
cur_ops->sync();
rcu_torture_pipe_update(old_rp);
@@ -1036,7 +1055,8 @@ rcu_torture_fakewriter(void *arg)
torture_random(&rand) % (nfakewriters * 8) == 0) {
cur_ops->cb_barrier();
} else if (gp_normal == gp_exp) {
- if (torture_random(&rand) & 0x80)
+ if (time_before(jiffies, rcutorture_noexp) ||
+ torture_random(&rand) & 0x80)
cur_ops->sync();
else
cur_ops->exp_sync();
--
1.8.1.5
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