Commit bc480a63 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcutorture: Add reader-side tests of polling grace-period API 

This commit adds reader-side testing of the polling grace-period API.
This testing verifies that a cookie obtained in an SRCU read-side critical
section does not get a true return from poll_state_synchronize_srcu()
within that same critical section.

Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/


Reported-by: default avatarKent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 0fd0548d

kernel/rcu/rcutorture.c

+10 −0
Original line number Diff line number Diff line
@@ -1429,6 +1429,7 @@ rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp, 
 */

static bool rcu_torture_one_read(struct torture_random_state *trsp)

{

	unsigned long cookie;

	int i;

	unsigned long started;

	unsigned long completed;
@@ -1444,6 +1445,8 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp) 
	WARN_ON_ONCE(!rcu_is_watching());

	newstate = rcutorture_extend_mask(readstate, trsp);

	rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);

	if (cur_ops->get_gp_state && cur_ops->poll_gp_state)

		cookie = cur_ops->get_gp_state();

	started = cur_ops->get_gp_seq();

	ts = rcu_trace_clock_local();

	p = rcu_dereference_check(rcu_torture_current,
@@ -1480,6 +1483,13 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp) 
	}

	__this_cpu_inc(rcu_torture_batch[completed]);

	preempt_enable();

	if (cur_ops->get_gp_state && cur_ops->poll_gp_state)

		WARN_ONCE(cur_ops->poll_gp_state(cookie),

			  "%s: Cookie check 3 failed %s(%d) %lu->%lu\n",

			  __func__,

			  rcu_torture_writer_state_getname(),

			  rcu_torture_writer_state,

			  cookie, cur_ops->get_gp_state());

	rcutorture_one_extend(&readstate, 0, trsp, rtrsp);

	WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);

	// This next splat is expected behavior if leakpointer, especially