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rcutorture: Disable fragile readers during overload testing

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Vanilla RCU readers, when either non-preemptible or preemptible with
priority-boosting enabled, can handle heavy overload conditions.
Other RCU implementations are more fragile.  This commit adds an
rcu_torture_ops structure field named ->rdrs_handle_load that is set
for non-fragile configurations of vanilla RCU, but cleared otherwise.
It also refrains from running fragile readers concurrently with overload
testing, thus avoiding false-positive overload-testing failures.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2026-08-05 13:18:58 -07:00
parent a04b2854be
commit d23e30d76c
1 changed files with 6 additions and 2 deletions
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8
kernel/rcu/rcutorture.c
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@ -440,6 +440,7 @@ struct rcu_torture_ops {
int debug_objects;
int start_poll_irqsoff;
int have_up_down;
int rdrs_handle_load;
const char *name;
};
@ -648,6 +649,7 @@ static struct rcu_torture_ops rcu_ops = {
.extendables = RCUTORTURE_MAX_EXTEND,
.debug_objects = 1,
.start_poll_irqsoff = 1,
.rdrs_handle_load = !IS_ENABLED(CONFIG_PREEMPT_RCU) || IS_ENABLED(CONFIG_RCU_BOOST),
.name = "rcu"
};
@ -2534,8 +2536,10 @@ static bool rcu_torture_one_read_start(struct rcu_torture_one_read_state *rtorsp
rtorsp->p = rcu_dereference_check(rcu_torture_current,
!cur_ops->readlock_held || cur_ops->readlock_held() ||
(rtorsp->readstate & RCUTORTURE_RDR_UPDOWN));
if (rtorsp->p == NULL) {
/* Wait for rcu_torture_writer to get underway */
if ((!cur_ops->rdrs_handle_load && atomic_read(&rcu_fwd_cb_nodelay)) || rtorsp->p == NULL) {
// Wait for rcu_torture_writer to get underway and
// (if readers cannot handle heavy loads) for any
// forward-progress testing to complete.
rcutorture_one_extend(&rtorsp->readstate, 0, trsp, rtorsp->rtrsp);
return false;
}