* [PATCH 0/7] Assorted rhashtables cleanups.
@ 2018-06-18 2:52 NeilBrown
2018-06-18 2:52 ` [PATCH 5/7] rhashtable: simplify nested_table_alloc() and rht_bucket_nested_insert() NeilBrown
` (7 more replies)
0 siblings, 8 replies; 9+ messages in thread
From: NeilBrown @ 2018-06-18 2:52 UTC (permalink / raw)
To: Thomas Graf, Herbert Xu, David Miller; +Cc: netdev, linux-kernel
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
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH 1/7] rhashtable: silence RCU warning in rhashtable_test.
2018-06-18 2:52 [PATCH 0/7] Assorted rhashtables cleanups NeilBrown
` (5 preceding siblings ...)
2018-06-18 2:52 ` [PATCH 4/7] rhashtable: simplify INIT_RHT_NULLS_HEAD() NeilBrown
@ 2018-06-18 2:52 ` NeilBrown
2018-06-22 4:43 ` [PATCH 0/7] Assorted rhashtables cleanups David Miller
7 siblings, 0 replies; 9+ messages in thread
From: NeilBrown @ 2018-06-18 2:52 UTC (permalink / raw)
To: Thomas Graf, Herbert Xu, David Miller; +Cc: netdev, linux-kernel
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;
}
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH 2/7] rhashtable: split rhashtable.h
2018-06-18 2:52 [PATCH 0/7] Assorted rhashtables cleanups NeilBrown
` (2 preceding siblings ...)
2018-06-18 2:52 ` [PATCH 3/7] rhashtable: remove nulls_base and related code NeilBrown
@ 2018-06-18 2:52 ` NeilBrown
2018-06-18 2:52 ` [PATCH 7/7] rhashtable: clean up dereference of ->future_tbl NeilBrown
` (3 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: NeilBrown @ 2018-06-18 2:52 UTC (permalink / raw)
To: Thomas Graf, Herbert Xu, David Miller; +Cc: netdev, linux-kernel
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>
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH 3/7] rhashtable: remove nulls_base and related code.
2018-06-18 2:52 [PATCH 0/7] Assorted rhashtables cleanups NeilBrown
2018-06-18 2:52 ` [PATCH 5/7] rhashtable: simplify nested_table_alloc() and rht_bucket_nested_insert() NeilBrown
2018-06-18 2:52 ` [PATCH 6/7] rhashtable: use cmpxchg() to protect ->future_tbl NeilBrown
@ 2018-06-18 2:52 ` NeilBrown
2018-06-18 2:52 ` [PATCH 2/7] rhashtable: split rhashtable.h NeilBrown
` (4 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: NeilBrown @ 2018-06-18 2:52 UTC (permalink / raw)
To: Thomas Graf, Herbert Xu, David Miller; +Cc: netdev, linux-kernel
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,
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH 4/7] rhashtable: simplify INIT_RHT_NULLS_HEAD()
2018-06-18 2:52 [PATCH 0/7] Assorted rhashtables cleanups NeilBrown
` (4 preceding siblings ...)
2018-06-18 2:52 ` [PATCH 7/7] rhashtable: clean up dereference of ->future_tbl NeilBrown
@ 2018-06-18 2:52 ` NeilBrown
2018-06-18 2:52 ` [PATCH 1/7] rhashtable: silence RCU warning in rhashtable_test NeilBrown
2018-06-22 4:43 ` [PATCH 0/7] Assorted rhashtables cleanups David Miller
7 siblings, 0 replies; 9+ messages in thread
From: NeilBrown @ 2018-06-18 2:52 UTC (permalink / raw)
To: Thomas Graf, Herbert Xu, David Miller; +Cc: netdev, linux-kernel
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)
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH 5/7] rhashtable: simplify nested_table_alloc() and rht_bucket_nested_insert()
2018-06-18 2:52 [PATCH 0/7] Assorted rhashtables cleanups NeilBrown
@ 2018-06-18 2:52 ` NeilBrown
2018-06-18 2:52 ` [PATCH 6/7] rhashtable: use cmpxchg() to protect ->future_tbl NeilBrown
` (6 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: NeilBrown @ 2018-06-18 2:52 UTC (permalink / raw)
To: Thomas Graf, Herbert Xu, David Miller; +Cc: netdev, linux-kernel
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)
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH 6/7] rhashtable: use cmpxchg() to protect ->future_tbl.
2018-06-18 2:52 [PATCH 0/7] Assorted rhashtables cleanups NeilBrown
2018-06-18 2:52 ` [PATCH 5/7] rhashtable: simplify nested_table_alloc() and rht_bucket_nested_insert() NeilBrown
@ 2018-06-18 2:52 ` NeilBrown
2018-06-18 2:52 ` [PATCH 3/7] rhashtable: remove nulls_base and related code NeilBrown
` (5 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: NeilBrown @ 2018-06-18 2:52 UTC (permalink / raw)
To: Thomas Graf, Herbert Xu, David Miller; +Cc: netdev, linux-kernel
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;
}
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH 7/7] rhashtable: clean up dereference of ->future_tbl.
2018-06-18 2:52 [PATCH 0/7] Assorted rhashtables cleanups NeilBrown
` (3 preceding siblings ...)
2018-06-18 2:52 ` [PATCH 2/7] rhashtable: split rhashtable.h NeilBrown
@ 2018-06-18 2:52 ` NeilBrown
2018-06-18 2:52 ` [PATCH 4/7] rhashtable: simplify INIT_RHT_NULLS_HEAD() NeilBrown
` (2 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: NeilBrown @ 2018-06-18 2:52 UTC (permalink / raw)
To: Thomas Graf, Herbert Xu, David Miller; +Cc: netdev, linux-kernel
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);
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH 0/7] Assorted rhashtables cleanups.
2018-06-18 2:52 [PATCH 0/7] Assorted rhashtables cleanups NeilBrown
` (6 preceding siblings ...)
2018-06-18 2:52 ` [PATCH 1/7] rhashtable: silence RCU warning in rhashtable_test NeilBrown
@ 2018-06-22 4:43 ` David Miller
7 siblings, 0 replies; 9+ messages in thread
From: David Miller @ 2018-06-22 4:43 UTC (permalink / raw)
To: neilb; +Cc: tgraf, herbert, netdev, linux-kernel
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.
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2018-06-22 4:45 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-06-18 2:52 [PATCH 0/7] Assorted rhashtables cleanups NeilBrown
2018-06-18 2:52 ` [PATCH 5/7] rhashtable: simplify nested_table_alloc() and rht_bucket_nested_insert() NeilBrown
2018-06-18 2:52 ` [PATCH 6/7] rhashtable: use cmpxchg() to protect ->future_tbl NeilBrown
2018-06-18 2:52 ` [PATCH 3/7] rhashtable: remove nulls_base and related code NeilBrown
2018-06-18 2:52 ` [PATCH 2/7] rhashtable: split rhashtable.h NeilBrown
2018-06-18 2:52 ` [PATCH 7/7] rhashtable: clean up dereference of ->future_tbl NeilBrown
2018-06-18 2:52 ` [PATCH 4/7] rhashtable: simplify INIT_RHT_NULLS_HEAD() NeilBrown
2018-06-18 2:52 ` [PATCH 1/7] rhashtable: silence RCU warning in rhashtable_test NeilBrown
2018-06-22 4:43 ` [PATCH 0/7] Assorted rhashtables cleanups David Miller
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