[PATCH tip/core/rcu 07/16] rcu: Add expedited-grace-period event tracing

From: Paul E. McKenney
Date: Tue Apr 12 2016 - 11:29:41 EST


Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 20 +++++++++++++-------
kernel/rcu/tree_plugin.h | 3 +++
2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 79e9206a7b11..524026fd9dd7 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3584,17 +3584,18 @@ static bool sync_exp_work_done(struct rcu_state *rsp, struct rcu_node *rnp,
atomic_long_t *stat, unsigned long s)
{
if (rcu_exp_gp_seq_done(rsp, s)) {
+ trace_rcu_exp_grace_period(rsp->name, s, TPS("done"));
if (rnp) {
- mutex_unlock(&rnp->exp_funnel_mutex);
trace_rcu_exp_funnel_lock(rsp->name, rnp->level,
rnp->grplo, rnp->grphi,
TPS("rel"));
+ mutex_unlock(&rnp->exp_funnel_mutex);
} else if (rdp) {
- mutex_unlock(&rdp->exp_funnel_mutex);
trace_rcu_exp_funnel_lock(rsp->name,
rdp->mynode->level + 1,
rdp->cpu, rdp->cpu,
TPS("rel"));
+ mutex_unlock(&rdp->exp_funnel_mutex);
}
/* Ensure test happens before caller kfree(). */
smp_mb__before_atomic(); /* ^^^ */
@@ -3624,12 +3625,12 @@ static struct rcu_node *exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
rnp0 = rcu_get_root(rsp);
if (!mutex_is_locked(&rnp0->exp_funnel_mutex)) {
if (mutex_trylock(&rnp0->exp_funnel_mutex)) {
- if (sync_exp_work_done(rsp, rnp0, NULL,
- &rdp->expedited_workdone0, s))
- return NULL;
trace_rcu_exp_funnel_lock(rsp->name, rnp0->level,
rnp0->grplo, rnp0->grphi,
TPS("acq"));
+ if (sync_exp_work_done(rsp, rnp0, NULL,
+ &rdp->expedited_workdone0, s))
+ return NULL;
return rnp0;
}
}
@@ -3656,16 +3657,16 @@ static struct rcu_node *exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
trace_rcu_exp_funnel_lock(rsp->name, rnp0->level,
rnp0->grplo, rnp0->grphi, TPS("acq"));
if (rnp1) {
- mutex_unlock(&rnp1->exp_funnel_mutex);
trace_rcu_exp_funnel_lock(rsp->name, rnp1->level,
rnp1->grplo, rnp1->grphi,
TPS("rel"));
+ mutex_unlock(&rnp1->exp_funnel_mutex);
} else {
- mutex_unlock(&rdp->exp_funnel_mutex);
trace_rcu_exp_funnel_lock(rsp->name,
rdp->mynode->level + 1,
rdp->cpu, rdp->cpu,
TPS("rel"));
+ mutex_unlock(&rdp->exp_funnel_mutex);
}
rnp1 = rnp0;
}
@@ -3895,16 +3896,21 @@ void synchronize_sched_expedited(void)

/* Take a snapshot of the sequence number. */
s = rcu_exp_gp_seq_snap(rsp);
+ trace_rcu_exp_grace_period(rsp->name, s, TPS("snap"));

rnp = exp_funnel_lock(rsp, s);
if (rnp == NULL)
return; /* Someone else did our work for us. */

rcu_exp_gp_seq_start(rsp);
+ trace_rcu_exp_grace_period(rsp->name, s, TPS("start"));
sync_rcu_exp_select_cpus(rsp, sync_sched_exp_handler);
synchronize_sched_expedited_wait(rsp);

rcu_exp_gp_seq_end(rsp);
+ trace_rcu_exp_grace_period(rsp->name, s, TPS("end"));
+ trace_rcu_exp_funnel_lock(rsp->name, rnp->level,
+ rnp->grplo, rnp->grphi, TPS("rel"));
mutex_unlock(&rnp->exp_funnel_mutex);
}
EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index cd2dae43ff48..36e94aed38a7 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -750,12 +750,14 @@ void synchronize_rcu_expedited(void)
}

s = rcu_exp_gp_seq_snap(rsp);
+ trace_rcu_exp_grace_period(rsp->name, s, TPS("snap"));

rnp_unlock = exp_funnel_lock(rsp, s);
if (rnp_unlock == NULL)
return; /* Someone else did our work for us. */

rcu_exp_gp_seq_start(rsp);
+ trace_rcu_exp_grace_period(rsp->name, s, TPS("start"));

/* Initialize the rcu_node tree in preparation for the wait. */
sync_rcu_exp_select_cpus(rsp, sync_rcu_exp_handler);
@@ -766,6 +768,7 @@ void synchronize_rcu_expedited(void)

/* Clean up and exit. */
rcu_exp_gp_seq_end(rsp);
+ trace_rcu_exp_grace_period(rsp->name, s, TPS("end"));
mutex_unlock(&rnp_unlock->exp_funnel_mutex);
trace_rcu_exp_funnel_lock(rsp->name, rnp_unlock->level,
rnp_unlock->grplo, rnp_unlock->grphi,
--
2.5.2