[PATCH 03/18] maple_tree: Add write lock checking with lockdep sequence numbers

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

Use the lockdep sequence numbers to ensure the write lock is not dropped
between write operations.  The lockdep sequence is recorded on any walk
that starts from the top of the tree and re-checked prior to any
operation using an active node.

Signed-off-by: Liam R. Howlett (Oracle) <liam@infradead.org>
---
 include/linux/maple_tree.h |  7 +++--
 lib/maple_tree.c           | 55 +++++++++++++++++++++++++++++---------
 2 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index 11a16c3508dc0..220b380cdd491 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -485,9 +485,12 @@ 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)
+#ifdef CONFIG_LOCKDEP
+	u32 ld_seq;
+#ifdef CONFIG_RCU_STRICT_GRACE_PERIOD
 	unsigned long rcu_gp;
-#endif
+#endif /* CONFIG_RCU_STRICT_GRACE_PERIOD */
+#endif /* CONFIG_LOCKDEP */
 };
 
 struct ma_wr_state {
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 7f310e8641669..1b2713190675d 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1153,40 +1153,68 @@ 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)
+
+#ifdef CONFIG_LOCKDEP
+struct lockdep_map *mas_lockdep_map(struct ma_state *mas)
+{
+	struct maple_tree *mt = mas->tree;
+
+	if (mt_external_lock(mt))
+		return mt->ma_external_lock;
+
+	return &(mt->ma_lock).dep_map;
+}
+
+#endif
+
+static void mas_lock_check(struct ma_state *mas)
 {
 
-#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)
+#ifdef CONFIG_LOCKDEP
 	if (!mas_is_active(mas))
 		return;
 
+#ifdef CONFIG_RCU_STRICT_GRACE_PERIOD
 	if (!mt_lock_is_held(mas->tree)) {
 		if (mt_in_rcu(mas->tree))
 			WARN_ON_ONCE(poll_state_synchronize_rcu(mas->rcu_gp));
 	}
-#endif
+#endif /* CONFIG_RCU_STRICT_GRACE_PERIOD */
+
+	if (mt_lock_is_held(mas->tree))
+		WARN_ON_ONCE(mas->ld_seq != lock_sequence(mas_lockdep_map(mas)));
+#endif /* CONFIG_LOCKDEP */
 
 }
 
-void mas_init_lock_check(struct ma_state *mas)
+static void mas_init_lock_check(struct ma_state *mas)
 {
-#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)
+#ifdef CONFIG_LOCKDEP
+#ifdef CONFIG_RCU_STRICT_GRACE_PERIOD
 	if (!mt_lock_is_held(mas->tree)) {
 		if (mt_in_rcu(mas->tree))
 			mas->rcu_gp = get_state_synchronize_rcu();
+		return;
 	}
-#endif
+#endif /* CONFIG_RCU_STRICT_GRACE_PERIOD */
+
+	if (mt_lock_is_held(mas->tree))
+		mas->ld_seq = lock_sequence(mas_lockdep_map(mas));
+#endif /* CONFIG_LOCKDEP */
 
 }
 
 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))
+#ifdef CONFIG_LOCKDEP
+#ifdef 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
+		return;
+	}
+#endif /* CONFIG_RCU_STRICT_GRACE_PERIOD */
+	mas_lock_check(mas);
+#endif /* CONFIG_LOCKDEP */
 }
 
 /*
@@ -4869,6 +4897,7 @@ void *mas_store(struct ma_state *mas, void *entry)
 {
 	MA_WR_STATE(wr_mas, mas, entry);
 
+	mas_may_init_lock_check(mas);
 	trace_ma_write(TP_FCT, mas, 0, entry);
 #ifdef CONFIG_DEBUG_MAPLE_TREE
 	if (MAS_WARN_ON(mas, mas->index > mas->last))
@@ -4927,6 +4956,7 @@ int mas_store_gfp(struct ma_state *mas, void *entry, gfp_t gfp)
 	MA_WR_STATE(wr_mas, mas, entry);
 	int ret = 0;
 
+	mas_may_init_lock_check(mas);
 retry:
 	mas_wr_preallocate(&wr_mas, entry);
 	if (unlikely(mas_nomem(mas, gfp))) {
@@ -4957,6 +4987,7 @@ void mas_store_prealloc(struct ma_state *mas, void *entry)
 {
 	MA_WR_STATE(wr_mas, mas, entry);
 
+	mas_lock_check(mas);
 	if (mas->store_type == wr_store_root) {
 		mas_wr_prealloc_setup(&wr_mas);
 		goto store;
@@ -4989,6 +5020,7 @@ int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp)
 {
 	MA_WR_STATE(wr_mas, mas, entry);
 
+	mas_may_init_lock_check(mas);
 	mas_wr_prealloc_setup(&wr_mas);
 	mas->store_type = mas_wr_store_type(&wr_mas);
 	mas_prealloc_calc(&wr_mas, entry);
@@ -5473,7 +5505,6 @@ EXPORT_SYMBOL_GPL(mas_find_range);
 static bool mas_find_rev_setup(struct ma_state *mas, unsigned long min,
 		void **entry)
 {
-
 	switch (mas->status) {
 	case ma_active:
 		goto active;
-- 
2.47.3