[PATCH tip/core/rcu 20/24] rcu: Clean up flavor-related definitions and comments in tree_plugin.h
From: Paul E. McKenney
Date: Wed Aug 29 2018 - 18:55:02 EST
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
kernel/rcu/tree_plugin.h | 36 +++++++++++++++++-------------------
1 file changed, 17 insertions(+), 19 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index cd276c46bc14..cd4c1b979446 100644
@@ -38,8 +38,7 @@
- * Control variables for per-CPU and per-rcu_node kthreads. These
- * handle all flavors of RCU.
+ * Control variables for per-CPU and per-rcu_node kthreads.
static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task);
DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
@@ -826,8 +825,8 @@ static void rcu_flavor_check_callbacks(int user)
* Note that this guarantee implies further memory-ordering guarantees.
* On systems with more than one CPU, when synchronize_rcu() returns,
- * each CPU is guaranteed to have executed a full memory barrier since the
- * end of its last RCU-sched read-side critical section whose beginning
+ * each CPU is guaranteed to have executed a full memory barrier since
+ * the end of its last RCU read-side critical section whose beginning
* preceded the call to synchronize_rcu(). In addition, each CPU having
* an RCU read-side critical section that extends beyond the return from
* synchronize_rcu() is guaranteed to have executed a full memory barrier
@@ -1069,7 +1068,7 @@ void synchronize_rcu(void)
- "Illegal synchronize_rcu() in RCU-sched read-side critical section");
+ "Illegal synchronize_rcu() in RCU read-side critical section");
@@ -1341,9 +1340,9 @@ static int rcu_cpu_kthread_should_run(unsigned int cpu)
- * Per-CPU kernel thread that invokes RCU callbacks. This replaces the
- * RCU softirq used in flavors and configurations of RCU that do not
- * support RCU priority boosting.
+ * Per-CPU kernel thread that invokes RCU callbacks. This replaces
+ * the RCU softirq used in configurations of RCU that do not support RCU
+ * priority boosting.
static void rcu_cpu_kthread(unsigned int cpu)
@@ -1484,8 +1483,8 @@ static void rcu_prepare_kthreads(int cpu)
* 1 if so. This function is part of the RCU implementation; it is -not-
* an exported member of the RCU API.
- * Because we not have RCU_FAST_NO_HZ, just check whether this CPU needs
- * any flavor of RCU.
+ * Because we not have RCU_FAST_NO_HZ, just check whether or not this
+ * CPU has RCU callbacks queued.
int rcu_needs_cpu(u64 basemono, u64 *nextevt)
@@ -1551,9 +1550,9 @@ static int rcu_idle_lazy_gp_delay = RCU_IDLE_LAZY_GP_DELAY;
module_param(rcu_idle_lazy_gp_delay, int, 0644);
- * Try to advance callbacks for all flavors of RCU on the current CPU, but
- * only if it has been awhile since the last time we did so. Afterwards,
- * if there are any callbacks ready for immediate invocation, return true.
+ * Try to advance callbacks on the current CPU, but only if it has been
+ * awhile since the last time we did so. Afterwards, if there are any
+ * callbacks ready for immediate invocation, return true.
static bool __maybe_unused rcu_try_advance_all_cbs(void)
@@ -1808,7 +1807,7 @@ static void print_cpu_stall_info_end(void)
-/* Zero ->ticks_this_gp for all flavors of RCU. */
+/* Zero ->ticks_this_gp and snapshot the number of RCU softirq handlers. */
static void zero_cpu_stall_ticks(struct rcu_data *rdp)
rdp->ticks_this_gp = 0;
@@ -1939,7 +1938,7 @@ static void wake_nocb_leader_defer(struct rcu_data *rdp, int waketype,
- * Does the specified CPU need an RCU callback for the specified flavor
+ * Does the specified CPU need an RCU callback for this invocation
* of rcu_barrier()?
static bool rcu_nocb_cpu_needs_barrier(int cpu)
@@ -2419,9 +2418,8 @@ static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
* If the specified CPU is a no-CBs CPU that does not already have its
- * rcuo kthread for the specified RCU flavor, spawn it. If the CPUs are
- * brought online out of order, this can require re-organizing the
- * leader-follower relationships.
+ * rcuo kthread, spawn it. If the CPUs are brought online out of order,
+ * this can require re-organizing the leader-follower relationships.
static void rcu_spawn_one_nocb_kthread(int cpu)
@@ -2458,7 +2456,7 @@ static void rcu_spawn_one_nocb_kthread(int cpu)
rdp_spawn->nocb_next_follower = rdp_old_leader;
- /* Spawn the kthread for this CPU and RCU flavor. */
+ /* Spawn the kthread for this CPU. */
t = kthread_run(rcu_nocb_kthread, rdp_spawn,
"rcuo%c/%d", rcu_state.abbr, cpu);