1 files changed, 71 insertions, 15 deletions

diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 05a221ce79a6..133ccb39137a 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -245,16 +245,17 @@ void *rhashtable_insert_slow(struct rhashtable *ht, const void *key,
 void rhashtable_walk_enter(struct rhashtable *ht,
 			   struct rhashtable_iter *iter);
 void rhashtable_walk_exit(struct rhashtable_iter *iter);
-int rhashtable_walk_start_check(struct rhashtable_iter *iter) __acquires(RCU);
+int rhashtable_walk_start_check(struct rhashtable_iter *iter) __acquires_shared(RCU);
 
 static inline void rhashtable_walk_start(struct rhashtable_iter *iter)
+	__acquires_shared(RCU)
 {
 	(void)rhashtable_walk_start_check(iter);
 }
 
 void *rhashtable_walk_next(struct rhashtable_iter *iter);
 void *rhashtable_walk_peek(struct rhashtable_iter *iter);
-void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU);
+void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases_shared(RCU);
 
 void rhashtable_free_and_destroy(struct rhashtable *ht,
 				 void (*free_fn)(void *ptr, void *arg),
@@ -325,6 +326,7 @@ static inline struct rhash_lock_head __rcu **rht_bucket_insert(
 
 static inline unsigned long rht_lock(struct bucket_table *tbl,
 				     struct rhash_lock_head __rcu **bkt)
+	__acquires(__bitlock(0, bkt))
 {
 	unsigned long flags;
 
@@ -337,6 +339,7 @@ static inline unsigned long rht_lock(struct bucket_table *tbl,
 static inline unsigned long rht_lock_nested(struct bucket_table *tbl,
 					struct rhash_lock_head __rcu **bucket,
 					unsigned int subclass)
+	__acquires(__bitlock(0, bucket))
 {
 	unsigned long flags;
 
@@ -349,18 +352,32 @@ static inline unsigned long rht_lock_nested(struct bucket_table *tbl,
 static inline void rht_unlock(struct bucket_table *tbl,
 			      struct rhash_lock_head __rcu **bkt,
 			      unsigned long flags)
+	__releases(__bitlock(0, bkt))
 {
 	lock_map_release(&tbl->dep_map);
 	bit_spin_unlock(0, (unsigned long *)bkt);
 	local_irq_restore(flags);
 }
 
-static inline struct rhash_head *__rht_ptr(
-	struct rhash_lock_head *p, struct rhash_lock_head __rcu *const *bkt)
+enum rht_lookup_freq {
+	RHT_LOOKUP_NORMAL,
+	RHT_LOOKUP_LIKELY,
+};
+
+static __always_inline struct rhash_head *__rht_ptr(
+	struct rhash_lock_head *p, struct rhash_lock_head __rcu *const *bkt,
+	const enum rht_lookup_freq freq)
 {
-	return (struct rhash_head *)
-		((unsigned long)p & ~BIT(0) ?:
-		 (unsigned long)RHT_NULLS_MARKER(bkt));
+	unsigned long p_val = (unsigned long)p & ~BIT(0);
+
+	BUILD_BUG_ON(!__builtin_constant_p(freq));
+
+	if (freq == RHT_LOOKUP_LIKELY)
+		return (struct rhash_head *)
+			(likely(p_val) ? p_val : (unsigned long)RHT_NULLS_MARKER(bkt));
+	else
+		return (struct rhash_head *)
+			(p_val ?: (unsigned long)RHT_NULLS_MARKER(bkt));
 }
 
 /*
@@ -370,10 +387,17 @@ static inline struct rhash_head *__rht_ptr(
  *   rht_ptr_exclusive() dereferences in a context where exclusive
  *            access is guaranteed, such as when destroying the table.
  */
+static __always_inline struct rhash_head *__rht_ptr_rcu(
+	struct rhash_lock_head __rcu *const *bkt,
+	const enum rht_lookup_freq freq)
+{
+	return __rht_ptr(rcu_dereference_all(*bkt), bkt, freq);
+}
+
 static inline struct rhash_head *rht_ptr_rcu(
 	struct rhash_lock_head __rcu *const *bkt)
 {
-	return __rht_ptr(rcu_dereference_all(*bkt), bkt);
+	return __rht_ptr_rcu(bkt, RHT_LOOKUP_NORMAL);
 }
 
 static inline struct rhash_head *rht_ptr(
@@ -381,13 +405,15 @@ static inline struct rhash_head *rht_ptr(
 	struct bucket_table *tbl,
 	unsigned int hash)
 {
-	return __rht_ptr(rht_dereference_bucket(*bkt, tbl, hash), bkt);
+	return __rht_ptr(rht_dereference_bucket(*bkt, tbl, hash), bkt,
+			 RHT_LOOKUP_NORMAL);
 }
 
 static inline struct rhash_head *rht_ptr_exclusive(
 	struct rhash_lock_head __rcu *const *bkt)
 {
-	return __rht_ptr(rcu_dereference_protected(*bkt, 1), bkt);
+	return __rht_ptr(rcu_dereference_protected(*bkt, 1), bkt,
+			 RHT_LOOKUP_NORMAL);
 }
 
 static inline void rht_assign_locked(struct rhash_lock_head __rcu **bkt,
@@ -402,13 +428,14 @@ static inline void rht_assign_unlock(struct bucket_table *tbl,
 				     struct rhash_lock_head __rcu **bkt,
 				     struct rhash_head *obj,
 				     unsigned long flags)
+	__releases(__bitlock(0, bkt))
 {
 	if (rht_is_a_nulls(obj))
 		obj = NULL;
 	lock_map_release(&tbl->dep_map);
 	rcu_assign_pointer(*bkt, (void *)obj);
 	preempt_enable();
-	__release(bitlock);
+	__release(__bitlock(0, bkt));
 	local_irq_restore(flags);
 }
 
@@ -588,7 +615,9 @@ static inline int rhashtable_compare(struct rhashtable_compare_arg *arg,
 /* Internal function, do not use. */
 static __always_inline struct rhash_head *__rhashtable_lookup(
 	struct rhashtable *ht, const void *key,
-	const struct rhashtable_params params)
+	const struct rhashtable_params params,
+	const enum rht_lookup_freq freq)
+	__must_hold_shared(RCU)
 {
 	struct rhashtable_compare_arg arg = {
 		.ht = ht,
@@ -599,12 +628,13 @@ static __always_inline struct rhash_head *__rhashtable_lookup(
 	struct rhash_head *he;
 	unsigned int hash;
 
+	BUILD_BUG_ON(!__builtin_constant_p(freq));
 	tbl = rht_dereference_rcu(ht->tbl, ht);
 restart:
 	hash = rht_key_hashfn(ht, tbl, key, params);
 	bkt = rht_bucket(tbl, hash);
 	do {
-		rht_for_each_rcu_from(he, rht_ptr_rcu(bkt), tbl, hash) {
+		rht_for_each_rcu_from(he, __rht_ptr_rcu(bkt, freq), tbl, hash) {
 			if (params.obj_cmpfn ?
 			    params.obj_cmpfn(&arg, rht_obj(ht, he)) :
 			    rhashtable_compare(&arg, rht_obj(ht, he)))
@@ -642,12 +672,25 @@ restart:
 static __always_inline void *rhashtable_lookup(
 	struct rhashtable *ht, const void *key,
 	const struct rhashtable_params params)
+	__must_hold_shared(RCU)
 {
-	struct rhash_head *he = __rhashtable_lookup(ht, key, params);
+	struct rhash_head *he = __rhashtable_lookup(ht, key, params,
+						    RHT_LOOKUP_NORMAL);
 
 	return he ? rht_obj(ht, he) : NULL;
 }
 
+static __always_inline void *rhashtable_lookup_likely(
+	struct rhashtable *ht, const void *key,
+	const struct rhashtable_params params)
+	__must_hold_shared(RCU)
+{
+	struct rhash_head *he = __rhashtable_lookup(ht, key, params,
+						    RHT_LOOKUP_LIKELY);
+
+	return likely(he) ? rht_obj(ht, he) : NULL;
+}
+
 /**
  * rhashtable_lookup_fast - search hash table, without RCU read lock
  * @ht:		hash table
@@ -692,12 +735,25 @@ static __always_inline void *rhashtable_lookup_fast(
 static __always_inline struct rhlist_head *rhltable_lookup(
 	struct rhltable *hlt, const void *key,
 	const struct rhashtable_params params)
+	__must_hold_shared(RCU)
 {
-	struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params);
+	struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params,
+						    RHT_LOOKUP_NORMAL);
 
 	return he ? container_of(he, struct rhlist_head, rhead) : NULL;
 }
 
+static __always_inline struct rhlist_head *rhltable_lookup_likely(
+	struct rhltable *hlt, const void *key,
+	const struct rhashtable_params params)
+	__must_hold_shared(RCU)
+{
+	struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params,
+						    RHT_LOOKUP_LIKELY);
+
+	return likely(he) ? container_of(he, struct rhlist_head, rhead) : NULL;
+}
+
 /* Internal function, please use rhashtable_insert_fast() instead. This
  * function returns the existing element already in hashes if there is a clash,
  * otherwise it returns an error via ERR_PTR().