Commit 0f38c06c authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Uladzislau Rezki (Sony)
Browse files

rcutorture: Check preemption for failing reader 



This commit checks to see if the RCU reader has been preempted within
its read-side critical section for RCU flavors supporting this notion
(currently only preemptible RCU).  If such a preemption occurred, then
this is printed at the end of the "Failure/close-call rcutorture reader
segments" list at the end of the rcutorture run.

[ paulmck: Apply kernel test robot feedback. ]

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Tested-by: default avatarkernel test robot <oliver.sang@intel.com>
Signed-off-by: default avatarUladzislau Rezki (Sony) <urezki@gmail.com>
parent 4569cf60

include/linux/rcupdate_wait.h

+11 −0
Original line number Diff line number Diff line
@@ -65,4 +65,15 @@ static inline void cond_resched_rcu(void) 
#endif

}



// Has the current task blocked within its current RCU read-side

// critical section?

static inline bool has_rcu_reader_blocked(void)

{

#ifdef CONFIG_PREEMPT_RCU

	return !list_empty(&current->rcu_node_entry);

#else

	return false;

#endif

}



#endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */

kernel/rcu/rcutorture.c

+11 −0
Original line number Diff line number Diff line
@@ -267,6 +267,7 @@ struct rt_read_seg { 
static int err_segs_recorded;

static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];

static int rt_read_nsegs;

static int rt_read_preempted;



static const char *rcu_torture_writer_state_getname(void)

{
@@ -394,6 +395,7 @@ struct rcu_torture_ops { 
	void (*get_gp_data)(int *flags, unsigned long *gp_seq);

	void (*gp_slow_register)(atomic_t *rgssp);

	void (*gp_slow_unregister)(atomic_t *rgssp);

	bool (*reader_blocked)(void);

	long cbflood_max;

	int irq_capable;

	int can_boost;
@@ -587,6 +589,9 @@ static struct rcu_torture_ops rcu_ops = { 
	.get_gp_data		= rcutorture_get_gp_data,

	.gp_slow_register	= rcu_gp_slow_register,

	.gp_slow_unregister	= rcu_gp_slow_unregister,

	.reader_blocked		= IS_ENABLED(CONFIG_RCU_TORTURE_TEST_LOG_CPU)

				  ? has_rcu_reader_blocked

				  : NULL,

	.irq_capable		= 1,

	.can_boost		= IS_ENABLED(CONFIG_RCU_BOOST),

	.extendables		= RCUTORTURE_MAX_EXTEND,
@@ -2035,6 +2040,7 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid) 
	int newstate;

	struct rcu_torture *p;

	int pipe_count;

	bool preempted = false;

	int readstate = 0;

	struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };

	struct rt_read_seg *rtrsp = &rtseg[0];
@@ -2100,6 +2106,8 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid) 
				  rcu_torture_writer_state,

				  cpumask_pr_args(cpu_online_mask));

	}

	if (cur_ops->reader_blocked)

		preempted = cur_ops->reader_blocked();

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

	WARN_ON_ONCE(readstate);

	// This next splat is expected behavior if leakpointer, especially
@@ -2112,6 +2120,7 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid) 
		for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)

			err_segs[i++] = *rtrsp1;

		rt_read_nsegs = i;

		rt_read_preempted = preempted;

	}



	return true;
@@ -3569,6 +3578,8 @@ rcu_torture_cleanup(void) 
			pr_cont("\n");



		}

		if (rt_read_preempted)

			pr_alert("\tReader was preempted.\n");

	}

	if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)

		rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");