[PATCH 0/7] Assorted rhashtables cleanups.

[PATCH 0/7] Assorted rhashtables cleanups.

[NeilBrown]

Following 7 patches are selections from a recent RFC series I posted
that have all received suitable Acks.

The most visible changes are that rhashtable-types.h is now preferred
for inclusion in include/linux/*.h rather than rhashtable.h, and
that the full hash is used - no bits a reserved for a NULLS pointer.

Thanks,
NeilBrown

---

NeilBrown (7):
      rhashtable: silence RCU warning in rhashtable_test.
      rhashtable: split rhashtable.h
      rhashtable: remove nulls_base and related code.
      rhashtable: simplify INIT_RHT_NULLS_HEAD()
      rhashtable: simplify nested_table_alloc() and rht_bucket_nested_insert()
      rhashtable: use cmpxchg() to protect ->future_tbl.
      rhashtable: clean up dereference of ->future_tbl.


 MAINTAINERS                                |    2 
 drivers/net/ethernet/chelsio/cxgb4/cxgb4.h |    1 
 include/linux/ipc.h                        |    2 
 include/linux/ipc_namespace.h              |    2 
 include/linux/mroute_base.h                |    2 
 include/linux/rhashtable-types.h           |  137 +++++++++++++++++++++++
 include/linux/rhashtable.h                 |  164 +---------------------------
 include/net/inet_frag.h                    |    2 
 include/net/netfilter/nf_flow_table.h      |    2 
 include/net/sctp/structs.h                 |    2 
 include/net/seg6.h                         |    2 
 include/net/seg6_hmac.h                    |    2 
 ipc/msg.c                                  |    1 
 ipc/sem.c                                  |    1 
 ipc/shm.c                                  |    1 
 ipc/util.c                                 |    1 
 lib/rhashtable.c                           |   58 +++-------
 lib/test_rhashtable.c                      |    8 +
 net/core/xdp.c                             |    4 -
 net/ipv4/inet_fragment.c                   |    1 
 net/ipv4/ipmr.c                            |    1 
 net/ipv4/ipmr_base.c                       |    1 
 net/ipv6/ip6mr.c                           |    1 
 net/ipv6/seg6.c                            |    1 
 net/ipv6/seg6_hmac.c                       |    1 
 net/netfilter/nf_tables_api.c              |    1 
 net/sctp/input.c                           |    1 
 net/sctp/socket.c                          |    1 
 28 files changed, 191 insertions(+), 212 deletions(-)
 create mode 100644 include/linux/rhashtable-types.h

--
Signature

[PATCH 1/7] rhashtable: silence RCU warning in rhashtable_test.

[NeilBrown]

print_ht in rhashtable_test calls rht_dereference() with neither
RCU protection or the mutex.  This triggers an RCU warning.
So take the mutex to silence the warning.

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NeilBrown <neilb@suse.com>
---
 lib/test_rhashtable.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c
index fb6968109113..6ca59ffcacbe 100644
--- a/lib/test_rhashtable.c
+++ b/lib/test_rhashtable.c
@@ -501,6 +501,8 @@ static unsigned int __init print_ht(struct rhltable *rhlt)
 	unsigned int i, cnt = 0;
 
 	ht = &rhlt->ht;
+	/* Take the mutex to avoid RCU warning */
+	mutex_lock(&ht->mutex);
 	tbl = rht_dereference(ht->tbl, ht);
 	for (i = 0; i < tbl->size; i++) {
 		struct rhash_head *pos, *next;
@@ -534,6 +536,7 @@ static unsigned int __init print_ht(struct rhltable *rhlt)
 		}
 	}
 	printk(KERN_ERR "\n---- ht: ----%s\n-------------\n", buff);
+	mutex_unlock(&ht->mutex);
 
 	return cnt;
 }

[PATCH 2/7] rhashtable: split rhashtable.h

[NeilBrown]

Due to the use of rhashtables in net namespaces,
rhashtable.h is included in lots of the kernel,
so a small changes can required a large recompilation.
This makes development painful.

This patch splits out rhashtable-types.h which just includes
the major type declarations, and does not include (non-trivial)
inline code.  rhashtable.h is no longer included by anything
in the include/ directory.
Common include files only include rhashtable-types.h so a large
recompilation is only triggered when that changes.

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NeilBrown <neilb@suse.com>
---
 MAINTAINERS                                |    2 
 drivers/net/ethernet/chelsio/cxgb4/cxgb4.h |    1 
 include/linux/ipc.h                        |    2 
 include/linux/ipc_namespace.h              |    2 
 include/linux/mroute_base.h                |    2 
 include/linux/rhashtable-types.h           |  139 ++++++++++++++++++++++++++++
 include/linux/rhashtable.h                 |  127 --------------------------
 include/net/inet_frag.h                    |    2 
 include/net/netfilter/nf_flow_table.h      |    2 
 include/net/sctp/structs.h                 |    2 
 include/net/seg6.h                         |    2 
 include/net/seg6_hmac.h                    |    2 
 ipc/msg.c                                  |    1 
 ipc/sem.c                                  |    1 
 ipc/shm.c                                  |    1 
 ipc/util.c                                 |    1 
 lib/rhashtable.c                           |    1 
 net/ipv4/inet_fragment.c                   |    1 
 net/ipv4/ipmr.c                            |    1 
 net/ipv4/ipmr_base.c                       |    1 
 net/ipv6/ip6mr.c                           |    1 
 net/ipv6/seg6.c                            |    1 
 net/ipv6/seg6_hmac.c                       |    1 
 net/netfilter/nf_tables_api.c              |    1 
 net/sctp/input.c                           |    1 
 net/sctp/socket.c                          |    1 
 26 files changed, 166 insertions(+), 133 deletions(-)
 create mode 100644 include/linux/rhashtable-types.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 9d5eeff51b5f..5b57d9078d79 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12162,7 +12162,9 @@ M:	Herbert Xu <herbert@gondor.apana.org.au>
 L:	netdev@vger.kernel.org
 S:	Maintained
 F:	lib/rhashtable.c
+F:	lib/test_rhashtable.c
 F:	include/linux/rhashtable.h
+F:	include/linux/rhashtable-types.h
 
 RICOH R5C592 MEMORYSTICK DRIVER
 M:	Maxim Levitsky <maximlevitsky@gmail.com>
diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h b/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h
index 0dbe2d9e22d6..1adb968b8354 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h
@@ -46,6 +46,7 @@
 #include <linux/spinlock.h>
 #include <linux/timer.h>
 #include <linux/vmalloc.h>
+#include <linux/rhashtable.h>
 #include <linux/etherdevice.h>
 #include <linux/net_tstamp.h>
 #include <linux/ptp_clock_kernel.h>
diff --git a/include/linux/ipc.h b/include/linux/ipc.h
index 6cc2df7f7ac9..e1c9eea6015b 100644
--- a/include/linux/ipc.h
+++ b/include/linux/ipc.h
@@ -4,7 +4,7 @@
 
 #include <linux/spinlock.h>
 #include <linux/uidgid.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 #include <uapi/linux/ipc.h>
 #include <linux/refcount.h>
 
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index b5630c8eb2f3..6cea726612b7 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -9,7 +9,7 @@
 #include <linux/nsproxy.h>
 #include <linux/ns_common.h>
 #include <linux/refcount.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 
 struct user_namespace;
 
diff --git a/include/linux/mroute_base.h b/include/linux/mroute_base.h
index d633f737b3c6..fd436cdd4725 100644
--- a/include/linux/mroute_base.h
+++ b/include/linux/mroute_base.h
@@ -2,7 +2,7 @@
 #define __LINUX_MROUTE_BASE_H
 
 #include <linux/netdevice.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 #include <linux/spinlock.h>
 #include <net/net_namespace.h>
 #include <net/sock.h>
diff --git a/include/linux/rhashtable-types.h b/include/linux/rhashtable-types.h
new file mode 100644
index 000000000000..9740063ff13b
--- /dev/null
+++ b/include/linux/rhashtable-types.h
@@ -0,0 +1,139 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Resizable, Scalable, Concurrent Hash Table
+ *
+ * Simple structures that might be needed in include
+ * files.
+ */
+
+#ifndef _LINUX_RHASHTABLE_TYPES_H
+#define _LINUX_RHASHTABLE_TYPES_H
+
+#include <linux/atomic.h>
+#include <linux/compiler.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+
+struct rhash_head {
+	struct rhash_head __rcu		*next;
+};
+
+struct rhlist_head {
+	struct rhash_head		rhead;
+	struct rhlist_head __rcu	*next;
+};
+
+struct bucket_table;
+
+/**
+ * struct rhashtable_compare_arg - Key for the function rhashtable_compare
+ * @ht: Hash table
+ * @key: Key to compare against
+ */
+struct rhashtable_compare_arg {
+	struct rhashtable *ht;
+	const void *key;
+};
+
+typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed);
+typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 len, u32 seed);
+typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg,
+			       const void *obj);
+
+/**
+ * struct rhashtable_params - Hash table construction parameters
+ * @nelem_hint: Hint on number of elements, should be 75% of desired size
+ * @key_len: Length of key
+ * @key_offset: Offset of key in struct to be hashed
+ * @head_offset: Offset of rhash_head in struct to be hashed
+ * @max_size: Maximum size while expanding
+ * @min_size: Minimum size while shrinking
+ * @locks_mul: Number of bucket locks to allocate per cpu (default: 32)
+ * @automatic_shrinking: Enable automatic shrinking of tables
+ * @nulls_base: Base value to generate nulls marker
+ * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash)
+ * @obj_hashfn: Function to hash object
+ * @obj_cmpfn: Function to compare key with object
+ */
+struct rhashtable_params {
+	u16			nelem_hint;
+	u16			key_len;
+	u16			key_offset;
+	u16			head_offset;
+	unsigned int		max_size;
+	u16			min_size;
+	bool			automatic_shrinking;
+	u8			locks_mul;
+	u32			nulls_base;
+	rht_hashfn_t		hashfn;
+	rht_obj_hashfn_t	obj_hashfn;
+	rht_obj_cmpfn_t		obj_cmpfn;
+};
+
+/**
+ * struct rhashtable - Hash table handle
+ * @tbl: Bucket table
+ * @key_len: Key length for hashfn
+ * @max_elems: Maximum number of elements in table
+ * @p: Configuration parameters
+ * @rhlist: True if this is an rhltable
+ * @run_work: Deferred worker to expand/shrink asynchronously
+ * @mutex: Mutex to protect current/future table swapping
+ * @lock: Spin lock to protect walker list
+ * @nelems: Number of elements in table
+ */
+struct rhashtable {
+	struct bucket_table __rcu	*tbl;
+	unsigned int			key_len;
+	unsigned int			max_elems;
+	struct rhashtable_params	p;
+	bool				rhlist;
+	struct work_struct		run_work;
+	struct mutex                    mutex;
+	spinlock_t			lock;
+	atomic_t			nelems;
+};
+
+/**
+ * struct rhltable - Hash table with duplicate objects in a list
+ * @ht: Underlying rhtable
+ */
+struct rhltable {
+	struct rhashtable ht;
+};
+
+/**
+ * struct rhashtable_walker - Hash table walker
+ * @list: List entry on list of walkers
+ * @tbl: The table that we were walking over
+ */
+struct rhashtable_walker {
+	struct list_head list;
+	struct bucket_table *tbl;
+};
+
+/**
+ * struct rhashtable_iter - Hash table iterator
+ * @ht: Table to iterate through
+ * @p: Current pointer
+ * @list: Current hash list pointer
+ * @walker: Associated rhashtable walker
+ * @slot: Current slot
+ * @skip: Number of entries to skip in slot
+ */
+struct rhashtable_iter {
+	struct rhashtable *ht;
+	struct rhash_head *p;
+	struct rhlist_head *list;
+	struct rhashtable_walker walker;
+	unsigned int slot;
+	unsigned int skip;
+	bool end_of_table;
+};
+
+int rhashtable_init(struct rhashtable *ht,
+		    const struct rhashtable_params *params);
+int rhltable_init(struct rhltable *hlt,
+		  const struct rhashtable_params *params);
+
+#endif /* _LINUX_RHASHTABLE_TYPES_H */
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 4e1f535c2034..48754ab07cdf 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Resizable, Scalable, Concurrent Hash Table
  *
@@ -17,16 +18,14 @@
 #ifndef _LINUX_RHASHTABLE_H
 #define _LINUX_RHASHTABLE_H
 
-#include <linux/atomic.h>
-#include <linux/compiler.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/jhash.h>
 #include <linux/list_nulls.h>
 #include <linux/workqueue.h>
-#include <linux/mutex.h>
 #include <linux/rculist.h>
 
+#include <linux/rhashtable-types.h>
 /*
  * The end of the chain is marked with a special nulls marks which has
  * the following format:
@@ -64,15 +63,6 @@
  */
 #define RHT_ELASTICITY	16u
 
-struct rhash_head {
-	struct rhash_head __rcu		*next;
-};
-
-struct rhlist_head {
-	struct rhash_head		rhead;
-	struct rhlist_head __rcu	*next;
-};
-
 /**
  * struct bucket_table - Table of hash buckets
  * @size: Number of hash buckets
@@ -102,114 +92,6 @@ struct bucket_table {
 	struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp;
 };
 
-/**
- * struct rhashtable_compare_arg - Key for the function rhashtable_compare
- * @ht: Hash table
- * @key: Key to compare against
- */
-struct rhashtable_compare_arg {
-	struct rhashtable *ht;
-	const void *key;
-};
-
-typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed);
-typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 len, u32 seed);
-typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg,
-			       const void *obj);
-
-struct rhashtable;
-
-/**
- * struct rhashtable_params - Hash table construction parameters
- * @nelem_hint: Hint on number of elements, should be 75% of desired size
- * @key_len: Length of key
- * @key_offset: Offset of key in struct to be hashed
- * @head_offset: Offset of rhash_head in struct to be hashed
- * @max_size: Maximum size while expanding
- * @min_size: Minimum size while shrinking
- * @locks_mul: Number of bucket locks to allocate per cpu (default: 32)
- * @automatic_shrinking: Enable automatic shrinking of tables
- * @nulls_base: Base value to generate nulls marker
- * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash)
- * @obj_hashfn: Function to hash object
- * @obj_cmpfn: Function to compare key with object
- */
-struct rhashtable_params {
-	u16			nelem_hint;
-	u16			key_len;
-	u16			key_offset;
-	u16			head_offset;
-	unsigned int		max_size;
-	u16			min_size;
-	bool			automatic_shrinking;
-	u8			locks_mul;
-	u32			nulls_base;
-	rht_hashfn_t		hashfn;
-	rht_obj_hashfn_t	obj_hashfn;
-	rht_obj_cmpfn_t		obj_cmpfn;
-};
-
-/**
- * struct rhashtable - Hash table handle
- * @tbl: Bucket table
- * @key_len: Key length for hashfn
- * @max_elems: Maximum number of elements in table
- * @p: Configuration parameters
- * @rhlist: True if this is an rhltable
- * @run_work: Deferred worker to expand/shrink asynchronously
- * @mutex: Mutex to protect current/future table swapping
- * @lock: Spin lock to protect walker list
- * @nelems: Number of elements in table
- */
-struct rhashtable {
-	struct bucket_table __rcu	*tbl;
-	unsigned int			key_len;
-	unsigned int			max_elems;
-	struct rhashtable_params	p;
-	bool				rhlist;
-	struct work_struct		run_work;
-	struct mutex                    mutex;
-	spinlock_t			lock;
-	atomic_t			nelems;
-};
-
-/**
- * struct rhltable - Hash table with duplicate objects in a list
- * @ht: Underlying rhtable
- */
-struct rhltable {
-	struct rhashtable ht;
-};
-
-/**
- * struct rhashtable_walker - Hash table walker
- * @list: List entry on list of walkers
- * @tbl: The table that we were walking over
- */
-struct rhashtable_walker {
-	struct list_head list;
-	struct bucket_table *tbl;
-};
-
-/**
- * struct rhashtable_iter - Hash table iterator
- * @ht: Table to iterate through
- * @p: Current pointer
- * @list: Current hash list pointer
- * @walker: Associated rhashtable walker
- * @slot: Current slot
- * @skip: Number of entries to skip in slot
- */
-struct rhashtable_iter {
-	struct rhashtable *ht;
-	struct rhash_head *p;
-	struct rhlist_head *list;
-	struct rhashtable_walker walker;
-	unsigned int slot;
-	unsigned int skip;
-	bool end_of_table;
-};
-
 static inline unsigned long rht_marker(const struct rhashtable *ht, u32 hash)
 {
 	return NULLS_MARKER(ht->p.nulls_base + hash);
@@ -376,11 +258,6 @@ static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl,
 }
 #endif /* CONFIG_PROVE_LOCKING */
 
-int rhashtable_init(struct rhashtable *ht,
-		    const struct rhashtable_params *params);
-int rhltable_init(struct rhltable *hlt,
-		  const struct rhashtable_params *params);
-
 void *rhashtable_insert_slow(struct rhashtable *ht, const void *key,
 			     struct rhash_head *obj);
 
diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index ed07e3786d98..f4272a29dc44 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -2,7 +2,7 @@
 #ifndef __NET_FRAG_H__
 #define __NET_FRAG_H__
 
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 
 struct netns_frags {
 	/* sysctls */
diff --git a/include/net/netfilter/nf_flow_table.h b/include/net/netfilter/nf_flow_table.h
index ba9fa4592f2b..0e355f4a3d76 100644
--- a/include/net/netfilter/nf_flow_table.h
+++ b/include/net/netfilter/nf_flow_table.h
@@ -4,7 +4,7 @@
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <linux/netdevice.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 #include <linux/rcupdate.h>
 #include <linux/netfilter/nf_conntrack_tuple_common.h>
 #include <net/dst.h>
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index dbe1b911a24d..e0f962d27386 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -48,7 +48,7 @@
 #define __sctp_structs_h__
 
 #include <linux/ktime.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 #include <linux/socket.h>	/* linux/in.h needs this!!    */
 #include <linux/in.h>		/* We get struct sockaddr_in. */
 #include <linux/in6.h>		/* We get struct in6_addr     */
diff --git a/include/net/seg6.h b/include/net/seg6.h
index e029e301faa5..2567941a2f32 100644
--- a/include/net/seg6.h
+++ b/include/net/seg6.h
@@ -18,7 +18,7 @@
 #include <linux/ipv6.h>
 #include <net/lwtunnel.h>
 #include <linux/seg6.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 
 static inline void update_csum_diff4(struct sk_buff *skb, __be32 from,
 				     __be32 to)
diff --git a/include/net/seg6_hmac.h b/include/net/seg6_hmac.h
index 69c3a106056b..7fda469e2758 100644
--- a/include/net/seg6_hmac.h
+++ b/include/net/seg6_hmac.h
@@ -22,7 +22,7 @@
 #include <linux/route.h>
 #include <net/seg6.h>
 #include <linux/seg6_hmac.h>
-#include <linux/rhashtable.h>
+#include <linux/rhashtable-types.h>
 
 #define SEG6_HMAC_MAX_DIGESTSIZE	160
 #define SEG6_HMAC_RING_SIZE		256
diff --git a/ipc/msg.c b/ipc/msg.c
index 3b6545302598..203281198079 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -38,6 +38,7 @@
 #include <linux/rwsem.h>
 #include <linux/nsproxy.h>
 #include <linux/ipc_namespace.h>
+#include <linux/rhashtable.h>
 
 #include <asm/current.h>
 #include <linux/uaccess.h>
diff --git a/ipc/sem.c b/ipc/sem.c
index 5af1943ad782..29c0347ef11d 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -86,6 +86,7 @@
 #include <linux/ipc_namespace.h>
 #include <linux/sched/wake_q.h>
 #include <linux/nospec.h>
+#include <linux/rhashtable.h>
 
 #include <linux/uaccess.h>
 #include "util.h"
diff --git a/ipc/shm.c b/ipc/shm.c
index 051a3e1fb8df..d4daf78df6da 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -43,6 +43,7 @@
 #include <linux/nsproxy.h>
 #include <linux/mount.h>
 #include <linux/ipc_namespace.h>
+#include <linux/rhashtable.h>
 
 #include <linux/uaccess.h>
 
diff --git a/ipc/util.c b/ipc/util.c
index 4e81182fa0ac..fdffff41f65b 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -63,6 +63,7 @@
 #include <linux/rwsem.h>
 #include <linux/memory.h>
 #include <linux/ipc_namespace.h>
+#include <linux/rhashtable.h>
 
 #include <asm/unistd.h>
 
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 9427b5766134..c9fafea7dc6e 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -28,6 +28,7 @@
 #include <linux/rhashtable.h>
 #include <linux/err.h>
 #include <linux/export.h>
+#include <linux/rhashtable.h>
 
 #define HASH_DEFAULT_SIZE	64UL
 #define HASH_MIN_SIZE		4U
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index c9e35b81d093..316518f87294 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -20,6 +20,7 @@
 #include <linux/skbuff.h>
 #include <linux/rtnetlink.h>
 #include <linux/slab.h>
+#include <linux/rhashtable.h>
 
 #include <net/sock.h>
 #include <net/inet_frag.h>
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 9f79b9803a16..82f914122f1b 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -60,6 +60,7 @@
 #include <linux/netfilter_ipv4.h>
 #include <linux/compat.h>
 #include <linux/export.h>
+#include <linux/rhashtable.h>
 #include <net/ip_tunnels.h>
 #include <net/checksum.h>
 #include <net/netlink.h>
diff --git a/net/ipv4/ipmr_base.c b/net/ipv4/ipmr_base.c
index cafb0506c8c9..1ad9aa62a97b 100644
--- a/net/ipv4/ipmr_base.c
+++ b/net/ipv4/ipmr_base.c
@@ -2,6 +2,7 @@
  * Common logic shared by IPv4 [ipmr] and IPv6 [ip6mr] implementation
  */
 
+#include <linux/rhashtable.h>
 #include <linux/mroute_base.h>
 
 /* Sets everything common except 'dev', since that is done under locking */
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 0d0f0053bb11..d0b7e0249c13 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -32,6 +32,7 @@
 #include <linux/seq_file.h>
 #include <linux/init.h>
 #include <linux/compat.h>
+#include <linux/rhashtable.h>
 #include <net/protocol.h>
 #include <linux/skbuff.h>
 #include <net/raw.h>
diff --git a/net/ipv6/seg6.c b/net/ipv6/seg6.c
index 0fdf2a55e746..8d0ba757a46c 100644
--- a/net/ipv6/seg6.c
+++ b/net/ipv6/seg6.c
@@ -17,6 +17,7 @@
 #include <linux/net.h>
 #include <linux/in6.h>
 #include <linux/slab.h>
+#include <linux/rhashtable.h>
 
 #include <net/ipv6.h>
 #include <net/protocol.h>
diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
index 33fb35cbfac1..b1791129a875 100644
--- a/net/ipv6/seg6_hmac.c
+++ b/net/ipv6/seg6_hmac.c
@@ -22,6 +22,7 @@
 #include <linux/icmpv6.h>
 #include <linux/mroute6.h>
 #include <linux/slab.h>
+#include <linux/rhashtable.h>
 
 #include <linux/netfilter.h>
 #include <linux/netfilter_ipv6.h>
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 896d4a36081d..3f211e1025c1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -14,6 +14,7 @@
 #include <linux/skbuff.h>
 #include <linux/netlink.h>
 #include <linux/vmalloc.h>
+#include <linux/rhashtable.h>
 #include <linux/netfilter.h>
 #include <linux/netfilter/nfnetlink.h>
 #include <linux/netfilter/nf_tables.h>
diff --git a/net/sctp/input.c b/net/sctp/input.c
index ba8a6e6c36fa..9bbc5f92c941 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -56,6 +56,7 @@
 #include <net/sctp/sm.h>
 #include <net/sctp/checksum.h>
 #include <net/net_namespace.h>
+#include <linux/rhashtable.h>
 
 /* Forward declarations for internal helpers. */
 static int sctp_rcv_ootb(struct sk_buff *);
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index d20f7addee19..0e91e83eea5a 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -66,6 +66,7 @@
 #include <linux/slab.h>
 #include <linux/file.h>
 #include <linux/compat.h>
+#include <linux/rhashtable.h>
 
 #include <net/ip.h>
 #include <net/icmp.h>

[PATCH 3/7] rhashtable: remove nulls_base and related code.

[NeilBrown]

This "feature" is unused, undocumented, and untested and so doesn't
really belong.  A patch is under development to properly implement
support for detecting when a search gets diverted down a different
chain, which the common purpose of nulls markers.

This patch actually fixes a bug too.  The table resizing allows a
table to grow to 2^31 buckets, but the hash is truncated to 27 bits -
any growth beyond 2^27 is wasteful an ineffective.

This patch results in NULLS_MARKER(0) being used for all chains,
and leaves the use of rht_is_a_null() to test for it.

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NeilBrown <neilb@suse.com>
---
 include/linux/rhashtable-types.h |    2 --
 include/linux/rhashtable.h       |   33 +++------------------------------
 lib/rhashtable.c                 |    8 --------
 lib/test_rhashtable.c            |    5 +----
 net/core/xdp.c                   |    4 ++--
 5 files changed, 6 insertions(+), 46 deletions(-)

diff --git a/include/linux/rhashtable-types.h b/include/linux/rhashtable-types.h
index 9740063ff13b..763d613ce2c2 100644
--- a/include/linux/rhashtable-types.h
+++ b/include/linux/rhashtable-types.h
@@ -50,7 +50,6 @@ typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg,
  * @min_size: Minimum size while shrinking
  * @locks_mul: Number of bucket locks to allocate per cpu (default: 32)
  * @automatic_shrinking: Enable automatic shrinking of tables
- * @nulls_base: Base value to generate nulls marker
  * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash)
  * @obj_hashfn: Function to hash object
  * @obj_cmpfn: Function to compare key with object
@@ -64,7 +63,6 @@ struct rhashtable_params {
 	u16			min_size;
 	bool			automatic_shrinking;
 	u8			locks_mul;
-	u32			nulls_base;
 	rht_hashfn_t		hashfn;
 	rht_obj_hashfn_t	obj_hashfn;
 	rht_obj_cmpfn_t		obj_cmpfn;
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 48754ab07cdf..d9f719af7936 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -28,25 +28,8 @@
 #include <linux/rhashtable-types.h>
 /*
  * The end of the chain is marked with a special nulls marks which has
- * the following format:
- *
- * +-------+-----------------------------------------------------+-+
- * | Base  |                      Hash                           |1|
- * +-------+-----------------------------------------------------+-+
- *
- * Base (4 bits) : Reserved to distinguish between multiple tables.
- *                 Specified via &struct rhashtable_params.nulls_base.
- * Hash (27 bits): Full hash (unmasked) of first element added to bucket
- * 1 (1 bit)     : Nulls marker (always set)
- *
- * The remaining bits of the next pointer remain unused for now.
+ * the least significant bit set.
  */
-#define RHT_BASE_BITS		4
-#define RHT_HASH_BITS		27
-#define RHT_BASE_SHIFT		RHT_HASH_BITS
-
-/* Base bits plus 1 bit for nulls marker */
-#define RHT_HASH_RESERVED_SPACE	(RHT_BASE_BITS + 1)
 
 /* Maximum chain length before rehash
  *
@@ -92,24 +75,14 @@ struct bucket_table {
 	struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp;
 };
 
-static inline unsigned long rht_marker(const struct rhashtable *ht, u32 hash)
-{
-	return NULLS_MARKER(ht->p.nulls_base + hash);
-}
-
 #define INIT_RHT_NULLS_HEAD(ptr, ht, hash) \
-	((ptr) = (typeof(ptr)) rht_marker(ht, hash))
+	((ptr) = (typeof(ptr)) NULLS_MARKER(0))
 
 static inline bool rht_is_a_nulls(const struct rhash_head *ptr)
 {
 	return ((unsigned long) ptr & 1);
 }
 
-static inline unsigned long rht_get_nulls_value(const struct rhash_head *ptr)
-{
-	return ((unsigned long) ptr) >> 1;
-}
-
 static inline void *rht_obj(const struct rhashtable *ht,
 			    const struct rhash_head *he)
 {
@@ -119,7 +92,7 @@ static inline void *rht_obj(const struct rhashtable *ht,
 static inline unsigned int rht_bucket_index(const struct bucket_table *tbl,
 					    unsigned int hash)
 {
-	return (hash >> RHT_HASH_RESERVED_SPACE) & (tbl->size - 1);
+	return hash & (tbl->size - 1);
 }
 
 static inline unsigned int rht_key_get_hash(struct rhashtable *ht,
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index c9fafea7dc6e..688693c919be 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -995,7 +995,6 @@ static u32 rhashtable_jhash2(const void *key, u32 length, u32 seed)
  *	.key_offset = offsetof(struct test_obj, key),
  *	.key_len = sizeof(int),
  *	.hashfn = jhash,
- *	.nulls_base = (1U << RHT_BASE_SHIFT),
  * };
  *
  * Configuration Example 2: Variable length keys
@@ -1029,9 +1028,6 @@ int rhashtable_init(struct rhashtable *ht,
 	    (params->obj_hashfn && !params->obj_cmpfn))
 		return -EINVAL;
 
-	if (params->nulls_base && params->nulls_base < (1U << RHT_BASE_SHIFT))
-		return -EINVAL;
-
 	memset(ht, 0, sizeof(*ht));
 	mutex_init(&ht->mutex);
 	spin_lock_init(&ht->lock);
@@ -1096,10 +1092,6 @@ int rhltable_init(struct rhltable *hlt, const struct rhashtable_params *params)
 {
 	int err;
 
-	/* No rhlist NULLs marking for now. */
-	if (params->nulls_base)
-		return -EINVAL;
-
 	err = rhashtable_init(&hlt->ht, params);
 	hlt->ht.rhlist = true;
 	return err;
diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c
index 6ca59ffcacbe..82ac39ce5310 100644
--- a/lib/test_rhashtable.c
+++ b/lib/test_rhashtable.c
@@ -83,7 +83,7 @@ static u32 my_hashfn(const void *data, u32 len, u32 seed)
 {
 	const struct test_obj_rhl *obj = data;
 
-	return (obj->value.id % 10) << RHT_HASH_RESERVED_SPACE;
+	return (obj->value.id % 10);
 }
 
 static int my_cmpfn(struct rhashtable_compare_arg *arg, const void *obj)
@@ -99,7 +99,6 @@ static struct rhashtable_params test_rht_params = {
 	.key_offset = offsetof(struct test_obj, value),
 	.key_len = sizeof(struct test_obj_val),
 	.hashfn = jhash,
-	.nulls_base = (3U << RHT_BASE_SHIFT),
 };
 
 static struct rhashtable_params test_rht_params_dup = {
@@ -296,8 +295,6 @@ static int __init test_rhltable(unsigned int entries)
 	if (!obj_in_table)
 		goto out_free;
 
-	/* nulls_base not supported in rhlist interface */
-	test_rht_params.nulls_base = 0;
 	err = rhltable_init(&rhlt, &test_rht_params);
 	if (WARN_ON(err))
 		goto out_free;
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 9d1f22072d5d..31c58719b5a9 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -45,8 +45,8 @@ static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed)
 	BUILD_BUG_ON(FIELD_SIZEOF(struct xdp_mem_allocator, mem.id)
 		     != sizeof(u32));
 
-	/* Use cyclic increasing ID as direct hash key, see rht_bucket_index */
-	return key << RHT_HASH_RESERVED_SPACE;
+	/* Use cyclic increasing ID as direct hash key */
+	return key;
 }
 
 static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg,

[PATCH 4/7] rhashtable: simplify INIT_RHT_NULLS_HEAD()

[NeilBrown]

The 'ht' and 'hash' arguments to INIT_RHT_NULLS_HEAD() are
no longer used - so drop them.  This allows us to also
remove the nhash argument from nested_table_alloc().

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NeilBrown <neilb@suse.com>
---
 include/linux/rhashtable.h |    2 +-
 lib/rhashtable.c           |   15 ++++++---------
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index d9f719af7936..3f3a182bd0b4 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -75,7 +75,7 @@ struct bucket_table {
 	struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp;
 };
 
-#define INIT_RHT_NULLS_HEAD(ptr, ht, hash) \
+#define INIT_RHT_NULLS_HEAD(ptr)	\
 	((ptr) = (typeof(ptr)) NULLS_MARKER(0))
 
 static inline bool rht_is_a_nulls(const struct rhash_head *ptr)
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 688693c919be..a81cd27d518c 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -116,8 +116,7 @@ static void bucket_table_free_rcu(struct rcu_head *head)
 
 static union nested_table *nested_table_alloc(struct rhashtable *ht,
 					      union nested_table __rcu **prev,
-					      unsigned int shifted,
-					      unsigned int nhash)
+					      unsigned int shifted)
 {
 	union nested_table *ntbl;
 	int i;
@@ -130,8 +129,7 @@ static union nested_table *nested_table_alloc(struct rhashtable *ht,
 
 	if (ntbl && shifted) {
 		for (i = 0; i < PAGE_SIZE / sizeof(ntbl[0].bucket); i++)
-			INIT_RHT_NULLS_HEAD(ntbl[i].bucket, ht,
-					    (i << shifted) | nhash);
+			INIT_RHT_NULLS_HEAD(ntbl[i].bucket);
 	}
 
 	rcu_assign_pointer(*prev, ntbl);
@@ -157,7 +155,7 @@ static struct bucket_table *nested_bucket_table_alloc(struct rhashtable *ht,
 		return NULL;
 
 	if (!nested_table_alloc(ht, (union nested_table __rcu **)tbl->buckets,
-				0, 0)) {
+				0)) {
 		kfree(tbl);
 		return NULL;
 	}
@@ -207,7 +205,7 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
 	tbl->hash_rnd = get_random_u32();
 
 	for (i = 0; i < nbuckets; i++)
-		INIT_RHT_NULLS_HEAD(tbl->buckets[i], ht, i);
+		INIT_RHT_NULLS_HEAD(tbl->buckets[i]);
 
 	return tbl;
 }
@@ -1217,7 +1215,7 @@ struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
 	nhash = index;
 	shifted = tbl->nest;
 	ntbl = nested_table_alloc(ht, &ntbl[index].table,
-				  size <= (1 << shift) ? shifted : 0, nhash);
+				  size <= (1 << shift) ? shifted : 0);
 
 	while (ntbl && size > (1 << shift)) {
 		index = hash & ((1 << shift) - 1);
@@ -1226,8 +1224,7 @@ struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
 		nhash |= index << shifted;
 		shifted += shift;
 		ntbl = nested_table_alloc(ht, &ntbl[index].table,
-					  size <= (1 << shift) ? shifted : 0,
-					  nhash);
+					  size <= (1 << shift) ? shifted : 0);
 	}
 
 	if (!ntbl)

[PATCH 5/7] rhashtable: simplify nested_table_alloc() and rht_bucket_nested_insert()

[NeilBrown]

Now that we don't use the hash value or shift in nested_table_alloc()
there is room for simplification.
We only need to pass a "is this a leaf" flag to nested_table_alloc(),
and don't need to track as much information in
rht_bucket_nested_insert().

Note there is another minor cleanup in nested_table_alloc() here.
The number of elements in a page of "union nested_tables" is most naturally

  PAGE_SIZE / sizeof(ntbl[0])

The previous code had

  PAGE_SIZE / sizeof(ntbl[0].bucket)

which happens to be the correct value only because the bucket uses all
the space in the union.

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NeilBrown <neilb@suse.com>
---
 lib/rhashtable.c |   18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index a81cd27d518c..2aa41c15df17 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -116,7 +116,7 @@ static void bucket_table_free_rcu(struct rcu_head *head)
 
 static union nested_table *nested_table_alloc(struct rhashtable *ht,
 					      union nested_table __rcu **prev,
-					      unsigned int shifted)
+					      bool leaf)
 {
 	union nested_table *ntbl;
 	int i;
@@ -127,8 +127,8 @@ static union nested_table *nested_table_alloc(struct rhashtable *ht,
 
 	ntbl = kzalloc(PAGE_SIZE, GFP_ATOMIC);
 
-	if (ntbl && shifted) {
-		for (i = 0; i < PAGE_SIZE / sizeof(ntbl[0].bucket); i++)
+	if (ntbl && leaf) {
+		for (i = 0; i < PAGE_SIZE / sizeof(ntbl[0]); i++)
 			INIT_RHT_NULLS_HEAD(ntbl[i].bucket);
 	}
 
@@ -155,7 +155,7 @@ static struct bucket_table *nested_bucket_table_alloc(struct rhashtable *ht,
 		return NULL;
 
 	if (!nested_table_alloc(ht, (union nested_table __rcu **)tbl->buckets,
-				0)) {
+				false)) {
 		kfree(tbl);
 		return NULL;
 	}
@@ -1207,24 +1207,18 @@ struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
 	unsigned int index = hash & ((1 << tbl->nest) - 1);
 	unsigned int size = tbl->size >> tbl->nest;
 	union nested_table *ntbl;
-	unsigned int shifted;
-	unsigned int nhash;
 
 	ntbl = (union nested_table *)rcu_dereference_raw(tbl->buckets[0]);
 	hash >>= tbl->nest;
-	nhash = index;
-	shifted = tbl->nest;
 	ntbl = nested_table_alloc(ht, &ntbl[index].table,
-				  size <= (1 << shift) ? shifted : 0);
+				  size <= (1 << shift));
 
 	while (ntbl && size > (1 << shift)) {
 		index = hash & ((1 << shift) - 1);
 		size >>= shift;
 		hash >>= shift;
-		nhash |= index << shifted;
-		shifted += shift;
 		ntbl = nested_table_alloc(ht, &ntbl[index].table,
-					  size <= (1 << shift) ? shifted : 0);
+					  size <= (1 << shift));
 	}
 
 	if (!ntbl)

[PATCH 6/7] rhashtable: use cmpxchg() to protect ->future_tbl.

[NeilBrown]

Rather than borrowing one of the bucket locks to
protect ->future_tbl updates, use cmpxchg().
This gives more freedom to change how bucket locking
is implemented.

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NeilBrown <neilb@suse.com>
---
 lib/rhashtable.c |   15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 2aa41c15df17..52ec83212856 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -297,21 +297,14 @@ static int rhashtable_rehash_attach(struct rhashtable *ht,
 				    struct bucket_table *old_tbl,
 				    struct bucket_table *new_tbl)
 {
-	/* Protect future_tbl using the first bucket lock. */
-	spin_lock_bh(old_tbl->locks);
-
-	/* Did somebody beat us to it? */
-	if (rcu_access_pointer(old_tbl->future_tbl)) {
-		spin_unlock_bh(old_tbl->locks);
-		return -EEXIST;
-	}
-
 	/* Make insertions go into the new, empty table right away. Deletions
 	 * and lookups will be attempted in both tables until we synchronize.
+	 * As cmpxchg() provides strong barriers, we do not need
+	 * rcu_assign_pointer().
 	 */
-	rcu_assign_pointer(old_tbl->future_tbl, new_tbl);
 
-	spin_unlock_bh(old_tbl->locks);
+	if (cmpxchg(&old_tbl->future_tbl, NULL, new_tbl) != NULL)
+		return -EEXIST;
 
 	return 0;
 }

[PATCH 7/7] rhashtable: clean up dereference of ->future_tbl.

[NeilBrown]

Using rht_dereference_bucket() to dereference
->future_tbl looks like a type error, and could be confusing.
Using rht_dereference_rcu() to test a pointer for NULL
adds an unnecessary barrier - rcu_access_pointer() is preferred
for NULL tests when no lock is held.

This uses 3 different ways to access ->future_tbl.
- if we know the mutex is held, use rht_dereference()
- if we don't hold the mutex, and are only testing for NULL,
  use rcu_access_pointer()
- otherwise (using RCU protection for true dereference),
  use rht_dereference_rcu().

Note that this includes a simplification of the call to
rhashtable_last_table() - we don't do an extra dereference
before the call any more.

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NeilBrown <neilb@suse.com>
---
 include/linux/rhashtable.h |    2 +-
 lib/rhashtable.c           |    9 ++++-----
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 3f3a182bd0b4..eb7111039247 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -595,7 +595,7 @@ static inline void *__rhashtable_insert_fast(
 	lock = rht_bucket_lock(tbl, hash);
 	spin_lock_bh(lock);
 
-	if (unlikely(rht_dereference_bucket(tbl->future_tbl, tbl, hash))) {
+	if (unlikely(rcu_access_pointer(tbl->future_tbl))) {
 slow_path:
 		spin_unlock_bh(lock);
 		rcu_read_unlock();
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 52ec83212856..0e04947b7e0c 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -226,8 +226,7 @@ static struct bucket_table *rhashtable_last_table(struct rhashtable *ht,
 static int rhashtable_rehash_one(struct rhashtable *ht, unsigned int old_hash)
 {
 	struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
-	struct bucket_table *new_tbl = rhashtable_last_table(ht,
-		rht_dereference_rcu(old_tbl->future_tbl, ht));
+	struct bucket_table *new_tbl = rhashtable_last_table(ht, old_tbl);
 	struct rhash_head __rcu **pprev = rht_bucket_var(old_tbl, old_hash);
 	int err = -EAGAIN;
 	struct rhash_head *head, *next, *entry;
@@ -467,7 +466,7 @@ static int rhashtable_insert_rehash(struct rhashtable *ht,
 
 fail:
 	/* Do not fail the insert if someone else did a rehash. */
-	if (likely(rcu_dereference_raw(tbl->future_tbl)))
+	if (likely(rcu_access_pointer(tbl->future_tbl)))
 		return 0;
 
 	/* Schedule async rehash to retry allocation in process context. */
@@ -540,7 +539,7 @@ static struct bucket_table *rhashtable_insert_one(struct rhashtable *ht,
 	if (PTR_ERR(data) != -EAGAIN && PTR_ERR(data) != -ENOENT)
 		return ERR_CAST(data);
 
-	new_tbl = rcu_dereference(tbl->future_tbl);
+	new_tbl = rht_dereference_rcu(tbl->future_tbl, ht);
 	if (new_tbl)
 		return new_tbl;
 
@@ -599,7 +598,7 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key,
 			break;
 
 		spin_unlock_bh(lock);
-		tbl = rcu_dereference(tbl->future_tbl);
+		tbl = rht_dereference_rcu(tbl->future_tbl, ht);
 	}
 
 	data = rhashtable_lookup_one(ht, tbl, hash, key, obj);

Re: [PATCH 0/7] Assorted rhashtables cleanups.

[David Miller]

From: NeilBrown <neilb@suse.com>
Date: Mon, 18 Jun 2018 12:52:50 +1000

> Following 7 patches are selections from a recent RFC series I posted
> that have all received suitable Acks.
> 
> The most visible changes are that rhashtable-types.h is now preferred
> for inclusion in include/linux/*.h rather than rhashtable.h, and
> that the full hash is used - no bits a reserved for a NULLS pointer.

Series applied to net-next, thanks Neil.