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authorPaul E. McKenney <paulmck@kernel.org>2020-03-11 17:39:12 -0700
committerPaul E. McKenney <paulmck@kernel.org>2020-05-07 10:15:28 -0700
commit19a8ff956c5abaaedfae23b8a951dd2d725a2171 (patch)
tree4413b34e7057c90d48cab3a085e5b50b96326f2a /kernel/rcu
parentbe44ae62431196ac2a55198c0855028fff3ccfb4 (diff)
rcutorture: Add flag to produce non-busy-wait task stalls
This commit aids testing of RCU task stall warning messages by adding an rcutorture.stall_cpu_block module parameter that results in the induced stall sleeping within the RCU read-side critical section. Spinning with interrupts disabled is still available via the rcutorture.stall_cpu_irqsoff module parameter, and specifying neither of these two module parameters will spin with preemption disabled. Note that sleeping (as opposed to preemption) results in additional complaints from RCU at context-switch time, so yet more testing. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/rcutorture.c17
1 files changed, 11 insertions, 6 deletions
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index d0345d14e22a..60dc36893aad 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -114,6 +114,7 @@ torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
torture_param(int, stall_cpu_holdoff, 10,
"Time to wait before starting stall (s).");
torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
+torture_param(int, stall_cpu_block, 0, "Sleep while stalling.");
torture_param(int, stat_interval, 60,
"Number of seconds between stats printk()s");
torture_param(int, stutter, 5, "Number of seconds to run/halt test");
@@ -1548,6 +1549,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
"test_boost=%d/%d test_boost_interval=%d "
"test_boost_duration=%d shutdown_secs=%d "
"stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
+ "stall_cpu_block=%d "
"n_barrier_cbs=%d "
"onoff_interval=%d onoff_holdoff=%d\n",
torture_type, tag, nrealreaders, nfakewriters,
@@ -1556,6 +1558,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
test_boost, cur_ops->can_boost,
test_boost_interval, test_boost_duration, shutdown_secs,
stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
+ stall_cpu_block,
n_barrier_cbs,
onoff_interval, onoff_holdoff);
}
@@ -1611,6 +1614,7 @@ static int rcutorture_booster_init(unsigned int cpu)
*/
static int rcu_torture_stall(void *args)
{
+ int idx;
unsigned long stop_at;
VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
@@ -1622,21 +1626,22 @@ static int rcu_torture_stall(void *args)
if (!kthread_should_stop()) {
stop_at = ktime_get_seconds() + stall_cpu;
/* RCU CPU stall is expected behavior in following code. */
- rcu_read_lock();
+ idx = cur_ops->readlock();
if (stall_cpu_irqsoff)
local_irq_disable();
- else
+ else if (!stall_cpu_block)
preempt_disable();
pr_alert("rcu_torture_stall start on CPU %d.\n",
- smp_processor_id());
+ raw_smp_processor_id());
while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
stop_at))
- continue; /* Induce RCU CPU stall warning. */
+ if (stall_cpu_block)
+ schedule_timeout_uninterruptible(HZ);
if (stall_cpu_irqsoff)
local_irq_enable();
- else
+ else if (!stall_cpu_block)
preempt_enable();
- rcu_read_unlock();
+ cur_ops->readunlock(idx);
pr_alert("rcu_torture_stall end.\n");
}
torture_shutdown_absorb("rcu_torture_stall");