During my study of RCU, I go through tree.c many times
and try to make some improvements to the comments.
Thanks a lot.
Signed-off-by: Zhouyi Zhou <zhouzhouyi@xxxxxxxxx>
---
kernel/rcu/tree.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index da6f5213fb74..50c6b8fd8d08 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -201,7 +201,7 @@ EXPORT_SYMBOL_GPL(rcu_get_gp_kthreads_prio);
* the need for long delays to increase some race probabilities with the
* need for fast grace periods to increase other race probabilities.
*/
-#define PER_RCU_NODE_PERIOD 3 /* Number of grace periods between delays. */
+#define PER_RCU_NODE_PERIOD 3 /* Number of grace periods between delays, for debug purpose. */
/*
* Compute the mask of online CPUs for the specified rcu_node structure.
@@ -835,9 +835,9 @@ void noinstr rcu_irq_exit(void)
/**
* rcu_irq_exit_preempt - Inform RCU that current CPU is exiting irq
- * towards in kernel preemption
+ * towards kernel preemption
*
- * Same as rcu_irq_exit() but has a sanity check that scheduling is safe
+ * Same as rcu_irq_exit() but has some sanity checks that scheduling is safe
* from RCU point of view. Invoked from return from interrupt before kernel
* preemption.
*/
@@ -959,7 +959,7 @@ EXPORT_SYMBOL_GPL(rcu_idle_exit);
*/
void noinstr rcu_user_exit(void)
{
- rcu_eqs_exit(1);
+ rcu_eqs_exit(true);
}
/**
@@ -1226,7 +1226,7 @@ EXPORT_SYMBOL_GPL(rcu_lockdep_current_cpu_online);
#endif /* #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU) */
/*
- * We are reporting a quiescent state on behalf of some other CPU, so
+ * We may reporting a quiescent state on behalf of some other CPU, so
* it is our responsibility to check for and handle potential overflow
* of the rcu_node ->gp_seq counter with respect to the rcu_data counters.
* After all, the CPU might be in deep idle state, and thus executing no
@@ -1808,9 +1808,9 @@ static bool rcu_gp_init(void)
return false;
}
- /* Advance to a new grace period and initialize state. */
- record_gp_stall_check_time();
/* Record GP times before starting GP, hence rcu_seq_start(). */
+ record_gp_stall_check_time();
+ /* Advance to a new grace period and initialize state. */
rcu_seq_start(&rcu_state.gp_seq);
ASSERT_EXCLUSIVE_WRITER(rcu_state.gp_seq);
trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("start"));
@@ -2630,7 +2630,7 @@ static void rcu_do_batch(struct rcu_data *rdp)
* state, for example, user mode or idle loop. It also schedules RCU
* core processing. If the current grace period has gone on too long,
* it will ask the scheduler to manufacture a context switch for the sole
- * purpose of providing a providing the needed quiescent state.
+ * purpose of providing the needed quiescent state.
*/
void rcu_sched_clock_irq(int user)
{
@@ -3260,7 +3260,7 @@ put_cached_bnode(struct kfree_rcu_cpu *krcp,
/*
* This function is invoked in workqueue context after a grace period.
- * It frees all the objects queued on ->bhead_free or ->head_free.
+ * It frees all the objects queued on ->bkvhead_free or ->head_free.
*/
static void kfree_rcu_work(struct work_struct *work)
{
@@ -3287,7 +3287,7 @@ static void kfree_rcu_work(struct work_struct *work)
krwp->head_free = NULL;
raw_spin_unlock_irqrestore(&krcp->lock, flags);
- // Handle two first channels.
+ // Handle first two channels.
for (i = 0; i < FREE_N_CHANNELS; i++) {
for (; bkvhead[i]; bkvhead[i] = bnext) {
bnext = bkvhead[i]->next;
@@ -3530,7 +3530,7 @@ kvfree_call_rcu_add_ptr_to_bulk(struct kfree_rcu_cpu *krcp, void *ptr)
/*
* Queue a request for lazy invocation of appropriate free routine after a
- * grace period. Please note there are three paths are maintained, two are the
+ * grace period. Please note there are three paths maintained, two are the
* main ones that use array of pointers interface and third one is emergency
* one, that is used only when the main path can not be maintained temporary,
* due to memory pressure.
@@ -3813,7 +3813,7 @@ EXPORT_SYMBOL_GPL(cond_synchronize_rcu);
/*
* Check to see if there is any immediate RCU-related work to be done by
- * the current CPU, returning 1 if so and zero otherwise. The checks are
+ * the current CPU, returning 1 if so and 0 otherwise. The checks are
* in order of increasing expense: checks that can be carried out against
* CPU-local state are performed first. However, we must check for CPU
* stalls first, else we might not get a chance.
@@ -4153,7 +4153,7 @@ int rcutree_online_cpu(unsigned int cpu)
}
/*
- * Near the beginning of the process. The CPU is still very much alive
+ * Near the beginning of the offline process. The CPU is still very much alive
* with pretty much all services enabled.
*/
int rcutree_offline_cpu(unsigned int cpu)
@@ -4651,7 +4651,7 @@ void __init rcu_init(void)
rcutree_online_cpu(cpu);
}
- /* Create workqueue for expedited GPs and for Tree SRCU. */
+ /* Create workqueue for Tree SRCU and for expedited GPs. */
rcu_gp_wq = alloc_workqueue("rcu_gp", WQ_MEM_RECLAIM, 0);
WARN_ON(!rcu_gp_wq);
rcu_par_gp_wq = alloc_workqueue("rcu_par_gp", WQ_MEM_RECLAIM, 0);
--
2.25.1
