[PATCH v2 16/27] rcu: Rename rcu_dynticks_snap() into rcu_watching_snap()

From: Valentin Schneider
Date: Tue Apr 30 2024 - 05:22:52 EST


The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, reflect that change in the related helpers.

Signed-off-by: Valentin Schneider <vschneid@xxxxxxxxxx>
---
.../Memory-Ordering/Tree-RCU-Memory-Ordering.rst | 2 +-
kernel/rcu/tree.c | 16 ++++++++--------
kernel/rcu/tree_exp.h | 2 +-
kernel/rcu/tree_stall.h | 4 ++--
4 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst b/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst
index 5750f125361b0..e8ef12ca1e9da 100644
--- a/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst
+++ b/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst
@@ -149,7 +149,7 @@ This case is handled by calls to the strongly ordered
``atomic_add_return()`` read-modify-write atomic operation that
is invoked within ``rcu_dynticks_eqs_enter()`` at idle-entry
time and within ``rcu_dynticks_eqs_exit()`` at idle-exit time.
-The grace-period kthread invokes ``rcu_dynticks_snap()`` and
+The grace-period kthread invokes ``rcu_watching_snap()`` and
``rcu_dynticks_in_eqs_since()`` (both of which invoke
an ``atomic_add_return()`` of zero) to detect idle CPUs.

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index fe2beb7d2e82d..857c2565efeac 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -297,17 +297,17 @@ static void rcu_watching_eqs_online(void)
}

/*
- * Snapshot the ->dynticks counter with full ordering so as to allow
+ * Snapshot the RCU_WATCHING counter with full ordering so as to allow
* stable comparison of this counter with past and future snapshots.
*/
-static int rcu_dynticks_snap(int cpu)
+static int rcu_watching_snap(int cpu)
{
smp_mb(); // Fundamental RCU ordering guarantee.
return ct_rcu_watching_cpu_acquire(cpu);
}

/*
- * Return true if the snapshot returned from rcu_dynticks_snap()
+ * Return true if the snapshot returned from rcu_watching_snap()
* indicates that RCU is in an extended quiescent state.
*/
static bool rcu_dynticks_in_eqs(int snap)
@@ -318,11 +318,11 @@ static bool rcu_dynticks_in_eqs(int snap)
/*
* Return true if the CPU corresponding to the specified rcu_data
* structure has spent some time in an extended quiescent state since
- * rcu_dynticks_snap() returned the specified snapshot.
+ * rcu_watching_snap() returned the specified snapshot.
*/
static bool rcu_dynticks_in_eqs_since(struct rcu_data *rdp, int snap)
{
- return snap != rcu_dynticks_snap(rdp->cpu);
+ return snap != rcu_watching_snap(rdp->cpu);
}

/*
@@ -770,7 +770,7 @@ static void rcu_gpnum_ovf(struct rcu_node *rnp, struct rcu_data *rdp)
*/
static int dyntick_save_progress_counter(struct rcu_data *rdp)
{
- rdp->dynticks_snap = rcu_dynticks_snap(rdp->cpu);
+ rdp->dynticks_snap = rcu_watching_snap(rdp->cpu);
if (rcu_dynticks_in_eqs(rdp->dynticks_snap)) {
trace_rcu_fqs(rcu_state.name, rdp->gp_seq, rdp->cpu, TPS("dti"));
rcu_gpnum_ovf(rdp->mynode, rdp);
@@ -2185,7 +2185,7 @@ static noinline void rcu_gp_cleanup(void)

// We get here either if there is no need for an
// additional grace period or if rcu_accelerate_cbs() has
- // already set the RCU_GP_FLAG_INIT bit in ->gp_flags. 
+ // already set the RCU_GP_FLAG_INIT bit in ->gp_flags.
// So all we need to do is to clear all of the other
// ->gp_flags bits.

@@ -4798,7 +4798,7 @@ rcu_boot_init_percpu_data(int cpu)
rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
INIT_WORK(&rdp->strict_work, strict_work_handler);
WARN_ON_ONCE(ct->nesting != 1);
- WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu)));
+ WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_watching_snap(cpu)));
rdp->barrier_seq_snap = rcu_state.barrier_sequence;
rdp->rcu_ofl_gp_seq = rcu_state.gp_seq;
rdp->rcu_ofl_gp_state = RCU_GP_CLEANED;
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 8a1d9c8bd9f74..50ec57304c1b7 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -357,7 +357,7 @@ static void __sync_rcu_exp_select_node_cpus(struct rcu_exp_work *rewp)
!(rnp->qsmaskinitnext & mask)) {
mask_ofl_test |= mask;
} else {
- snap = rcu_dynticks_snap(cpu);
+ snap = rcu_watching_snap(cpu);
if (rcu_dynticks_in_eqs(snap))
mask_ofl_test |= mask;
else
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 6cb346952e3e4..4fa23f9fc207f 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -501,7 +501,7 @@ static void print_cpu_stall_info(int cpu)
}
delta = rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq);
falsepositive = rcu_is_gp_kthread_starving(NULL) &&
- rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu));
+ rcu_dynticks_in_eqs(rcu_watching_snap(cpu));
rcuc_starved = rcu_is_rcuc_kthread_starving(rdp, &j);
if (rcuc_starved)
// Print signed value, as negative values indicate a probable bug.
@@ -515,7 +515,7 @@ static void print_cpu_stall_info(int cpu)
rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' :
"!."[!delta],
ticks_value, ticks_title,
- rcu_dynticks_snap(cpu) & 0xffff,
+ rcu_watching_snap(cpu) & 0xffff,
ct_nesting_cpu(cpu), ct_nmi_nesting_cpu(cpu),
rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
--
2.43.0