[tip: locking/core] lockdep: Improve comments in wait-type checks

[tip-bot2 for Zhouyi Zhou]

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     a2e05ddda11b0bd529f443df9089ab498b2c2642
Gitweb:        https://git.kernel.org/tip/a2e05ddda11b0bd529f443df9089ab498b2c2642
Author:        Zhouyi Zhou <zhouzhouyi@xxxxxxxxx>
AuthorDate:    Wed, 11 Aug 2021 10:59:20 +08:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 17 Sep 2021 15:08:45 +02:00

lockdep: Improve comments in wait-type checks

Comments in wait-type checks be improved by mentioning the
PREEPT_RT kernel configure option.

Signed-off-by: Zhouyi Zhou <zhouzhouyi@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20210811025920.20751-1-zhouzhouyi@xxxxxxxxx
---
 include/linux/lockdep_types.h | 2 +-
 kernel/locking/lockdep.c      | 2 +-
 kernel/rcu/update.c           | 4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/lockdep_types.h b/include/linux/lockdep_types.h
index 3e726ac..d224308 100644
--- a/include/linux/lockdep_types.h
+++ b/include/linux/lockdep_types.h
@@ -21,7 +21,7 @@ enum lockdep_wait_type {
 	LD_WAIT_SPIN,		/* spin loops, raw_spinlock_t etc.. */
 
 #ifdef CONFIG_PROVE_RAW_LOCK_NESTING
-	LD_WAIT_CONFIG,		/* CONFIG_PREEMPT_LOCK, spinlock_t etc.. */
+	LD_WAIT_CONFIG,		/* preemptible in PREEMPT_RT, spinlock_t etc.. */
 #else
 	LD_WAIT_CONFIG = LD_WAIT_SPIN,
 #endif
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index bfa0a34..4e63129 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4671,7 +4671,7 @@ print_lock_invalid_wait_context(struct task_struct *curr,
 /*
  * Verify the wait_type context.
  *
- * This check validates we takes locks in the right wait-type order; that is it
+ * This check validates we take locks in the right wait-type order; that is it
  * ensures that we do not take mutexes inside spinlocks and do not attempt to
  * acquire spinlocks inside raw_spinlocks and the sort.
  *
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index c21b38c..690b0ce 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -247,7 +247,7 @@ struct lockdep_map rcu_lock_map = {
 	.name = "rcu_read_lock",
 	.key = &rcu_lock_key,
 	.wait_type_outer = LD_WAIT_FREE,
-	.wait_type_inner = LD_WAIT_CONFIG, /* XXX PREEMPT_RCU ? */
+	.wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_RT implies PREEMPT_RCU */
 };
 EXPORT_SYMBOL_GPL(rcu_lock_map);
 
@@ -256,7 +256,7 @@ struct lockdep_map rcu_bh_lock_map = {
 	.name = "rcu_read_lock_bh",
 	.key = &rcu_bh_lock_key,
 	.wait_type_outer = LD_WAIT_FREE,
-	.wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_LOCK also makes BH preemptible */
+	.wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_RT makes BH preemptible. */
 };
 EXPORT_SYMBOL_GPL(rcu_bh_lock_map);