[PATCH v2 01/19] maple_tree: Add rcu locking check when LOCKDEP is enabled

["Liam R. Howlett (Oracle)" <liam@infradead.org>]

When CONFIG_LOCKDEP and CONFIG_RCU_STRICT_GRACE_PERIOD is enabled, check
for rcu locking issues by recording the grace period in the maple state
and checking the rcu window is still valid whenever the maple state is
reused with a state that is not MA_START or MA_PAUSED.

Signed-off-by: Liam R. Howlett (Oracle) <liam@infradead.org>
---
 include/linux/maple_tree.h |  3 +++
 lib/maple_tree.c           | 50 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index 4a5631906affb..11a16c3508dc0 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -485,6 +485,9 @@ struct ma_state {
 	unsigned char mas_flags;
 	unsigned char end;		/* The end of the node */
 	enum store_type store_type;	/* The type of store needed for this operation */
+#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)
+	unsigned long rcu_gp;
+#endif
 };
 
 struct ma_wr_state {
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index e52876435b77f..3dff0435c13a7 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1153,6 +1153,42 @@ static inline void mas_free(struct ma_state *mas, struct maple_enode *used)
 	ma_free_rcu(mte_to_node(used));
 }
 
+void mas_lock_check(struct ma_state *mas)
+{
+
+#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)
+	if (!mas_is_active(mas))
+		return;
+
+	if (!mt_locked(mas->tree)) {
+		if (mt_in_rcu(mas->tree))
+			WARN_ON_ONCE(poll_state_synchronize_rcu(mas->rcu_gp));
+	}
+#endif
+
+}
+
+void mas_init_lock_check(struct ma_state *mas)
+{
+#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)
+	if (!mt_locked(mas->tree)) {
+		if (mt_in_rcu(mas->tree))
+			mas->rcu_gp = get_state_synchronize_rcu();
+	}
+#endif
+
+}
+
+static void mas_may_init_lock_check(struct ma_state *mas)
+{
+#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)
+	if (mas_is_start(mas) || mas_is_paused(mas))
+		mas_init_lock_check(mas);
+	else
+		mas_lock_check(mas);
+#endif
+}
+
 /*
  * mas_start() - Sets up maple state for operations.
  * @mas: The maple state.
@@ -1171,6 +1207,7 @@ static inline struct maple_enode *mas_start(struct ma_state *mas)
 	if (likely(mas_is_start(mas))) {
 		struct maple_enode *root;
 
+		mas_init_lock_check(mas);
 		mas->min = 0;
 		mas->max = ULONG_MAX;
 
@@ -4360,6 +4397,7 @@ void *mas_walk(struct ma_state *mas)
 {
 	void *entry;
 
+	mas_may_init_lock_check(mas);
 	if (!mas_is_active(mas) && !mas_is_start(mas))
 		mas->status = ma_start;
 retry:
@@ -4997,6 +5035,7 @@ static void mas_may_activate(struct ma_state *mas)
 		mas->status = ma_start;
 	} else {
 		mas->status = ma_active;
+		mas_lock_check(mas);
 	}
 }
 
@@ -5074,6 +5113,7 @@ void *mas_next(struct ma_state *mas, unsigned long max)
 {
 	void *entry = NULL;
 
+	mas_may_init_lock_check(mas);
 	if (mas_next_setup(mas, max, &entry))
 		return entry;
 
@@ -5097,6 +5137,7 @@ void *mas_next_range(struct ma_state *mas, unsigned long max)
 {
 	void *entry = NULL;
 
+	mas_may_init_lock_check(mas);
 	if (mas_next_setup(mas, max, &entry))
 		return entry;
 
@@ -5205,6 +5246,7 @@ void *mas_prev(struct ma_state *mas, unsigned long min)
 {
 	void *entry = NULL;
 
+	mas_may_init_lock_check(mas);
 	if (mas_prev_setup(mas, min, &entry))
 		return entry;
 
@@ -5228,6 +5270,7 @@ void *mas_prev_range(struct ma_state *mas, unsigned long min)
 {
 	void *entry = NULL;
 
+	mas_may_init_lock_check(mas);
 	if (mas_prev_setup(mas, min, &entry))
 		return entry;
 
@@ -5274,6 +5317,7 @@ EXPORT_SYMBOL_GPL(mt_prev);
  */
 void mas_pause(struct ma_state *mas)
 {
+	mas_lock_check(mas);
 	mas->status = ma_pause;
 	mas->node = NULL;
 }
@@ -5382,6 +5426,7 @@ void *mas_find(struct ma_state *mas, unsigned long max)
 {
 	void *entry = NULL;
 
+	mas_may_init_lock_check(mas);
 	if (mas_find_setup(mas, max, &entry))
 		return entry;
 
@@ -5409,6 +5454,7 @@ void *mas_find_range(struct ma_state *mas, unsigned long max)
 {
 	void *entry = NULL;
 
+	mas_may_init_lock_check(mas);
 	if (mas_find_setup(mas, max, &entry))
 		return entry;
 
@@ -5521,6 +5567,7 @@ void *mas_find_rev(struct ma_state *mas, unsigned long min)
 {
 	void *entry = NULL;
 
+	mas_may_init_lock_check(mas);
 	if (mas_find_rev_setup(mas, min, &entry))
 		return entry;
 
@@ -5547,6 +5594,7 @@ void *mas_find_range_rev(struct ma_state *mas, unsigned long min)
 {
 	void *entry = NULL;
 
+	mas_may_init_lock_check(mas);
 	if (mas_find_rev_setup(mas, min, &entry))
 		return entry;
 
@@ -5623,7 +5671,7 @@ bool mas_nomem(struct ma_state *mas, gfp_t gfp)
 	if (!mas->sheaf && !mas->alloc)
 		return false;
 
-	mas->status = ma_start;
+	mas_reset(mas);
 	return true;
 }
 
-- 
2.47.3