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rcutorture: Check preemption for failing reader

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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: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Tested-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
This commit is contained in:
Paul E. McKenney 2024-10-28 13:07:11 -07:00 committed by Uladzislau Rezki (Sony)
parent 4569cf60b6
commit 0f38c06cab
2 changed files with 22 additions and 0 deletions
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11
include/linux/rcupdate_wait.h
View File

@ -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 */

11
kernel/rcu/rcutorture.c
View File

@ -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");