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rcutorture: Thread rcu_fwd pointer through forward-progress functions

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In order to add multiple kthreads, it will be necessary to allow
the various functions to operate on a pointer to their kthread's
rcu_fwd structure.  This commit therefore starts the process of
adding the needed "struct rcu_fwd" parameters and arguments to the
various callback forward-progress functions.

Note that rcutorture_oom_notify() and rcu_torture_fwd_cb_hist() will
eventually need to iterate over all kthreads' rcu_fwd structures.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2019-11-05 09:08:58 -08:00
parent a289e608b3
commit 6b1b832546
1 changed files with 41 additions and 37 deletions
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78
kernel/rcu/rcutorture.c
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@ -1661,6 +1661,7 @@ static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
struct rcu_fwd_cb {
struct rcu_head rh;
struct rcu_fwd_cb *rfc_next;
struct rcu_fwd *rfc_rfp;
int rfc_gps;
};
@ -1692,24 +1693,24 @@ struct rcu_fwd rcu_fwds = {
bool rcu_fwd_emergency_stop;
static void rcu_torture_fwd_cb_hist(void)
static void rcu_torture_fwd_cb_hist(struct rcu_fwd *rfp)
{
unsigned long gps;
unsigned long gps_old;
int i;
int j;
for (i = ARRAY_SIZE(rcu_fwds.n_launders_hist) - 1; i > 0; i--)
if (rcu_fwds.n_launders_hist[i].n_launders > 0)
for (i = ARRAY_SIZE(rfp->n_launders_hist) - 1; i > 0; i--)
if (rfp->n_launders_hist[i].n_launders > 0)
break;
pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
__func__, jiffies - rcu_fwds.rcu_fwd_startat);
gps_old = rcu_fwds.rcu_launder_gp_seq_start;
__func__, jiffies - rfp->rcu_fwd_startat);
gps_old = rfp->rcu_launder_gp_seq_start;
for (j = 0; j <= i; j++) {
gps = rcu_fwds.n_launders_hist[j].launder_gp_seq;
gps = rfp->n_launders_hist[j].launder_gp_seq;
pr_cont(" %ds/%d: %ld:%ld",
j + 1, FWD_CBS_HIST_DIV,
rcu_fwds.n_launders_hist[j].n_launders,
rfp->n_launders_hist[j].n_launders,
rcutorture_seq_diff(gps, gps_old));
gps_old = gps;
}
@ -1723,20 +1724,21 @@ static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
int i;
struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
struct rcu_fwd_cb **rfcpp;
struct rcu_fwd *rfp = rfcp->rfc_rfp;
rfcp->rfc_next = NULL;
rfcp->rfc_gps++;
spin_lock_irqsave(&rcu_fwds.rcu_fwd_lock, flags);
rfcpp = rcu_fwds.rcu_fwd_cb_tail;
rcu_fwds.rcu_fwd_cb_tail = &rfcp->rfc_next;
spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
rfcpp = rfp->rcu_fwd_cb_tail;
rfp->rcu_fwd_cb_tail = &rfcp->rfc_next;
WRITE_ONCE(*rfcpp, rfcp);
WRITE_ONCE(rcu_fwds.n_launders_cb, rcu_fwds.n_launders_cb + 1);
i = ((jiffies - rcu_fwds.rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
if (i >= ARRAY_SIZE(rcu_fwds.n_launders_hist))
i = ARRAY_SIZE(rcu_fwds.n_launders_hist) - 1;
rcu_fwds.n_launders_hist[i].n_launders++;
rcu_fwds.n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
spin_unlock_irqrestore(&rcu_fwds.rcu_fwd_lock, flags);
WRITE_ONCE(rfp->n_launders_cb, rfp->n_launders_cb + 1);
i = ((jiffies - rfp->rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
if (i >= ARRAY_SIZE(rfp->n_launders_hist))
i = ARRAY_SIZE(rfp->n_launders_hist) - 1;
rfp->n_launders_hist[i].n_launders++;
rfp->n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
}
// Give the scheduler a chance, even on nohz_full CPUs.
@ -1786,7 +1788,8 @@ static unsigned long rcu_torture_fwd_prog_cbfree(void)
}
/* Carry out need_resched()/cond_resched() forward-progress testing. */
static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
static void rcu_torture_fwd_prog_nr(struct rcu_fwd *rfp,
int *tested, int *tested_tries)
{
unsigned long cver;
unsigned long dur;
@ -1816,8 +1819,8 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
sd = cur_ops->stall_dur() + 1;
sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
dur = sd4 + torture_random(&trs) % (sd - sd4);
WRITE_ONCE(rcu_fwds.rcu_fwd_startat, jiffies);
stopat = rcu_fwds.rcu_fwd_startat + dur;
WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
stopat = rfp->rcu_fwd_startat + dur;
while (time_before(jiffies, stopat) &&
!shutdown_time_arrived() &&
!READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
@ -1852,7 +1855,7 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
}
/* Carry out call_rcu() forward-progress testing. */
static void rcu_torture_fwd_prog_cr(void)
static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
{
unsigned long cver;
unsigned long flags;
@ -1876,23 +1879,23 @@ static void rcu_torture_fwd_prog_cr(void)
/* Loop continuously posting RCU callbacks. */
WRITE_ONCE(rcu_fwd_cb_nodelay, true);
cur_ops->sync(); /* Later readers see above write. */
WRITE_ONCE(rcu_fwds.rcu_fwd_startat, jiffies);
stopat = rcu_fwds.rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
stopat = rfp->rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
n_launders = 0;
rcu_fwds.n_launders_cb = 0; // Hoist initialization for multi-kthread
rfp->n_launders_cb = 0; // Hoist initialization for multi-kthread
n_launders_sa = 0;
n_max_cbs = 0;
n_max_gps = 0;
for (i = 0; i < ARRAY_SIZE(rcu_fwds.n_launders_hist); i++)
rcu_fwds.n_launders_hist[i].n_launders = 0;
for (i = 0; i < ARRAY_SIZE(rfp->n_launders_hist); i++)
rfp->n_launders_hist[i].n_launders = 0;
cver = READ_ONCE(rcu_torture_current_version);
gps = cur_ops->get_gp_seq();
rcu_fwds.rcu_launder_gp_seq_start = gps;
rfp->rcu_launder_gp_seq_start = gps;
tick_dep_set_task(current, TICK_DEP_BIT_RCU);
while (time_before(jiffies, stopat) &&
!shutdown_time_arrived() &&
!READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
rfcp = READ_ONCE(rcu_fwds.rcu_fwd_cb_head);
rfcp = READ_ONCE(rfp->rcu_fwd_cb_head);
rfcpn = NULL;
if (rfcp)
rfcpn = READ_ONCE(rfcp->rfc_next);
@ -1900,7 +1903,7 @@ static void rcu_torture_fwd_prog_cr(void)
if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
break;
rcu_fwds.rcu_fwd_cb_head = rfcpn;
rfp->rcu_fwd_cb_head = rfcpn;
n_launders++;
n_launders_sa++;
} else {
@ -1912,6 +1915,7 @@ static void rcu_torture_fwd_prog_cr(void)
n_max_cbs++;
n_launders_sa = 0;
rfcp->rfc_gps = 0;
rfcp->rfc_rfp = rfp;
}
cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
@ -1922,7 +1926,7 @@ static void rcu_torture_fwd_prog_cr(void)
}
}
stoppedat = jiffies;
n_launders_cb_snap = READ_ONCE(rcu_fwds.n_launders_cb);
n_launders_cb_snap = READ_ONCE(rfp->n_launders_cb);
cver = READ_ONCE(rcu_torture_current_version) - cver;
gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
@ -1933,12 +1937,11 @@ static void rcu_torture_fwd_prog_cr(void)
WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n",
__func__,
stoppedat - rcu_fwds.rcu_fwd_startat,
jiffies - stoppedat,
stoppedat - rfp->rcu_fwd_startat, jiffies - stoppedat,
n_launders + n_max_cbs - n_launders_cb_snap,
n_launders, n_launders_sa,
n_max_gps, n_max_cbs, cver, gps);
rcu_torture_fwd_cb_hist();
rcu_torture_fwd_cb_hist(rfp);
}
schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
@ -1955,7 +1958,7 @@ static int rcutorture_oom_notify(struct notifier_block *self,
{
WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
__func__);
rcu_torture_fwd_cb_hist();
rcu_torture_fwd_cb_hist(&rcu_fwds);
rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwds.rcu_fwd_startat)) / 2);
WRITE_ONCE(rcu_fwd_emergency_stop, true);
smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
@ -1980,6 +1983,7 @@ static struct notifier_block rcutorture_oom_nb = {
/* Carry out grace-period forward-progress testing. */
static int rcu_torture_fwd_prog(void *args)
{
struct rcu_fwd *rfp = args;
int tested = 0;
int tested_tries = 0;
@ -1991,8 +1995,8 @@ static int rcu_torture_fwd_prog(void *args)
schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
WRITE_ONCE(rcu_fwd_emergency_stop, false);
register_oom_notifier(&rcutorture_oom_nb);
rcu_torture_fwd_prog_nr(&tested, &tested_tries);
rcu_torture_fwd_prog_cr();
rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);
rcu_torture_fwd_prog_cr(rfp);
unregister_oom_notifier(&rcutorture_oom_nb);
/* Avoid slow periods, better to test when busy. */
@ -2027,7 +2031,7 @@ static int __init rcu_torture_fwd_prog_init(void)
if (fwd_progress_div <= 0)
fwd_progress_div = 4;
return torture_create_kthread(rcu_torture_fwd_prog,
NULL, fwd_prog_task);
&rcu_fwds, fwd_prog_task);
}
/* Callback function for RCU barrier testing. */