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rcutorture: Add ability to limit callback-flood intensity

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The RCU tasks flavors of RCU now need concurrent callback flooding to
test their ability to switch between single-queue mode and per-CPU queue
mode, but their lack of heavy-duty forward-progress features rules out
the use of rcutorture's current callback-flooding code.  This commit
therefore provides the ability to limit the intensity of the callback
floods using a new ->cbflood_max field in the rcu_operations structure.
When this field is zero, there is no limit, otherwise, each callback-flood
kthread allocates at most ->cbflood_max callbacks.

Cc: Neeraj Upadhyay <neeraj.iitr10@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2021-11-23 11:53:52 -08:00
parent 82e310033d
commit 613b00fbe6
1 changed files with 14 additions and 5 deletions
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17
kernel/rcu/rcutorture.c
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@ -348,6 +348,7 @@ struct rcu_torture_ops {
void (*gp_kthread_dbg)(void);
bool (*check_boost_failed)(unsigned long gp_state, int *cpup);
int (*stall_dur)(void);
long cbflood_max;
int irq_capable;
int can_boost;
int extendables;
@ -841,6 +842,7 @@ static struct rcu_torture_ops tasks_rude_ops = {
.call = call_rcu_tasks_rude,
.cb_barrier = rcu_barrier_tasks_rude,
.gp_kthread_dbg = show_rcu_tasks_rude_gp_kthread,
.cbflood_max = 50000,
.fqs = NULL,
.stats = NULL,
.irq_capable = 1,
@ -881,6 +883,7 @@ static struct rcu_torture_ops tasks_tracing_ops = {
.call = call_rcu_tasks_trace,
.cb_barrier = rcu_barrier_tasks_trace,
.gp_kthread_dbg = show_rcu_tasks_trace_gp_kthread,
.cbflood_max = 50000,
.fqs = NULL,
.stats = NULL,
.irq_capable = 1,
@ -2387,7 +2390,7 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
rfp->rcu_fwd_cb_head = rfcpn;
n_launders++;
n_launders_sa++;
} else {
} else if (!cur_ops->cbflood_max || cur_ops->cbflood_max > n_max_cbs) {
rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
if (WARN_ON_ONCE(!rfcp)) {
schedule_timeout_interruptible(1);
@ -2397,7 +2400,10 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
n_launders_sa = 0;
rfcp->rfc_gps = 0;
rfcp->rfc_rfp = rfp;
} else {
rfcp = NULL;
}
if (rfcp)
cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
if (tick_nohz_full_enabled()) {
@ -2506,8 +2512,10 @@ static int rcu_torture_fwd_prog(void *args)
pr_alert("%s: Starting forward-progress test %d\n", __func__, rfp->rcu_fwd_id);
if (rcu_inkernel_boot_has_ended() && torture_num_online_cpus() > rfp->rcu_fwd_id)
rcu_torture_fwd_prog_cr(rfp);
if (!IS_ENABLED(CONFIG_TINY_RCU) ||
(rcu_inkernel_boot_has_ended() && torture_num_online_cpus() > rfp->rcu_fwd_id))
if ((cur_ops->stall_dur && cur_ops->stall_dur() > 0) &&
(!IS_ENABLED(CONFIG_TINY_RCU) ||
(rcu_inkernel_boot_has_ended() &&
torture_num_online_cpus() > rfp->rcu_fwd_id)))
rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);
/* Avoid slow periods, better to test when busy. */
@ -2539,7 +2547,8 @@ static int __init rcu_torture_fwd_prog_init(void)
fwd_progress = nr_cpu_ids;
}
if ((!cur_ops->sync && !cur_ops->call) ||
!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 || cur_ops == &rcu_busted_ops) {
(!cur_ops->cbflood_max && (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0)) ||
cur_ops == &rcu_busted_ops) {
VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
fwd_progress = 0;
return 0;