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Merge branch 'rhashtable-bitlocks' 

NeilBrown says:

====================
Convert rhashtable to use bitlocks

This series converts rhashtable to use a per-bucket bitlock
rather than a separate array of spinlocks.
This:
  reduces memory usage
  results in slightly fewer memory accesses
  slightly improves parallelism
  makes a configuration option unnecessary

The main change from previous version is to use a distinct type for
the pointer in the bucket which has a bit-lock in it.  This
helped find two places where rht_ptr() was missed, one
in  rhashtable_free_and_destroy() in print_ht in the test code.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2019-04-07 19:12:12 -07:00
parent 1e045a62ee 149212f078
commit 9186c90bbb
12 changed files with 270 additions and 172 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/rhashtable-types.h
View File

@ -48,7 +48,6 @@ typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg,
* @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
* @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash)
* @obj_hashfn: Function to hash object
@ -62,7 +61,6 @@ struct rhashtable_params {
unsigned int max_size;
u16 min_size;
bool automatic_shrinking;
u8 locks_mul;
rht_hashfn_t hashfn;
rht_obj_hashfn_t obj_hashfn;
rht_obj_cmpfn_t obj_cmpfn;

271
include/linux/rhashtable.h
View File

@ -24,12 +24,27 @@
#include <linux/list_nulls.h>
#include <linux/workqueue.h>
#include <linux/rculist.h>
#include <linux/bit_spinlock.h>
#include <linux/rhashtable-types.h>
/*
* Objects in an rhashtable have an embedded struct rhash_head
* which is linked into as hash chain from the hash table - or one
* of two or more hash tables when the rhashtable is being resized.
* The end of the chain is marked with a special nulls marks which has
* the least significant bit set.
* the least significant bit set but otherwise stores the address of
* the hash bucket. This allows us to be be sure we've found the end
* of the right list.
* The value stored in the hash bucket has BIT(2) used as a lock bit.
* This bit must be atomically set before any changes are made to
* the chain. To avoid dereferencing this pointer without clearing
* the bit first, we use an opaque 'struct rhash_lock_head *' for the
* pointer stored in the bucket. This struct needs to be defined so
* that rcu_derefernce() works on it, but it has no content so a
* cast is needed for it to be useful. This ensures it isn't
* used by mistake with clearing the lock bit first.
*/
struct rhash_lock_head {};
/* Maximum chain length before rehash
*
@ -52,8 +67,6 @@
* @nest: Number of bits of first-level nested table.
* @rehash: Current bucket being rehashed
* @hash_rnd: Random seed to fold into hash
* @locks_mask: Mask to apply before accessing locks[]
* @locks: Array of spinlocks protecting individual buckets
* @walkers: List of active walkers
* @rcu: RCU structure for freeing the table
* @future_tbl: Table under construction during rehashing
@ -64,16 +77,87 @@ struct bucket_table {
unsigned int size;
unsigned int nest;
u32 hash_rnd;
unsigned int locks_mask;
spinlock_t *locks;
struct list_head walkers;
struct rcu_head rcu;
struct bucket_table __rcu *future_tbl;
struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp;
struct lockdep_map dep_map;
struct rhash_lock_head __rcu *buckets[] ____cacheline_aligned_in_smp;
};
/*
* We lock a bucket by setting BIT(1) in the pointer - this is always
* zero in real pointers and in the nulls marker.
* bit_spin_locks do not handle contention well, but the whole point
* of the hashtable design is to achieve minimum per-bucket contention.
* A nested hash table might not have a bucket pointer. In that case
* we cannot get a lock. For remove and replace the bucket cannot be
* interesting and doesn't need locking.
* For insert we allocate the bucket if this is the last bucket_table,
* and then take the lock.
* Sometimes we unlock a bucket by writing a new pointer there. In that
* case we don't need to unlock, but we do need to reset state such as
* local_bh. For that we have rht_assign_unlock(). As rcu_assign_pointer()
* provides the same release semantics that bit_spin_unlock() provides,
* this is safe.
*/
static inline void rht_lock(struct bucket_table *tbl,
struct rhash_lock_head **bkt)
{
local_bh_disable();
bit_spin_lock(1, (unsigned long *)bkt);
lock_map_acquire(&tbl->dep_map);
}
static inline void rht_lock_nested(struct bucket_table *tbl,
struct rhash_lock_head **bucket,
unsigned int subclass)
{
local_bh_disable();
bit_spin_lock(1, (unsigned long *)bucket);
lock_acquire_exclusive(&tbl->dep_map, subclass, 0, NULL, _THIS_IP_);
}
static inline void rht_unlock(struct bucket_table *tbl,
struct rhash_lock_head **bkt)
{
lock_map_release(&tbl->dep_map);
bit_spin_unlock(1, (unsigned long *)bkt);
local_bh_enable();
}
static inline void rht_assign_unlock(struct bucket_table *tbl,
struct rhash_lock_head **bkt,
struct rhash_head *obj)
{
struct rhash_head **p = (struct rhash_head **)bkt;
lock_map_release(&tbl->dep_map);
rcu_assign_pointer(*p, obj);
preempt_enable();
__release(bitlock);
local_bh_enable();
}
/*
* If 'p' is a bucket head and might be locked:
* rht_ptr() returns the address without the lock bit.
* rht_ptr_locked() returns the address WITH the lock bit.
*/
static inline struct rhash_head __rcu *rht_ptr(const struct rhash_lock_head *p)
{
return (void *)(((unsigned long)p) & ~BIT(1));
}
static inline struct rhash_lock_head __rcu *rht_ptr_locked(const
struct rhash_head *p)
{
return (void *)(((unsigned long)p) | BIT(1));
}
/*
* NULLS_MARKER() expects a hash value with the low
* bits mostly likely to be significant, and it discards
@ -206,25 +290,6 @@ static inline bool rht_grow_above_max(const struct rhashtable *ht,
return atomic_read(&ht->nelems) >= ht->max_elems;
}
/* The bucket lock is selected based on the hash and protects mutations
* on a group of hash buckets.
*
* A maximum of tbl->size/2 bucket locks is allocated. This ensures that
* a single lock always covers both buckets which may both contains
* entries which link to the same bucket of the old table during resizing.
* This allows to simplify the locking as locking the bucket in both
* tables during resize always guarantee protection.
*
* IMPORTANT: When holding the bucket lock of both the old and new table
* during expansions and shrinking, the old bucket lock must always be
* acquired first.
*/
static inline spinlock_t *rht_bucket_lock(const struct bucket_table *tbl,
unsigned int hash)
{
return &tbl->locks[hash & tbl->locks_mask];
}
#ifdef CONFIG_PROVE_LOCKING
int lockdep_rht_mutex_is_held(struct rhashtable *ht);
int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash);
@ -263,11 +328,13 @@ void rhashtable_free_and_destroy(struct rhashtable *ht,
void *arg);
void rhashtable_destroy(struct rhashtable *ht);
struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,
unsigned int hash);
struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
struct bucket_table *tbl,
struct rhash_lock_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,
unsigned int hash);
struct rhash_lock_head __rcu **__rht_bucket_nested(const struct bucket_table *tbl,
unsigned int hash);
struct rhash_lock_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
struct bucket_table *tbl,
unsigned int hash);
#define rht_dereference(p, ht) \
rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
@ -284,21 +351,21 @@ struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
#define rht_entry(tpos, pos, member) \
({ tpos = container_of(pos, typeof(*tpos), member); 1; })
static inline struct rhash_head __rcu *const *rht_bucket(
static inline struct rhash_lock_head __rcu *const *rht_bucket(
const struct bucket_table *tbl, unsigned int hash)
{
return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) :
&tbl->buckets[hash];
}
static inline struct rhash_head __rcu **rht_bucket_var(
static inline struct rhash_lock_head __rcu **rht_bucket_var(
struct bucket_table *tbl, unsigned int hash)
{
return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) :
return unlikely(tbl->nest) ? __rht_bucket_nested(tbl, hash) :
&tbl->buckets[hash];
}
static inline struct rhash_head __rcu **rht_bucket_insert(
static inline struct rhash_lock_head __rcu **rht_bucket_insert(
struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash)
{
return unlikely(tbl->nest) ? rht_bucket_nested_insert(ht, tbl, hash) :
@ -324,7 +391,7 @@ static inline struct rhash_head __rcu **rht_bucket_insert(
* @hash: the hash value / bucket index
*/
#define rht_for_each(pos, tbl, hash) \
rht_for_each_from(pos, *rht_bucket(tbl, hash), tbl, hash)
rht_for_each_from(pos, rht_ptr(*rht_bucket(tbl, hash)), tbl, hash)
/**
* rht_for_each_entry_from - iterate over hash chain from given head
@ -349,7 +416,7 @@ static inline struct rhash_head __rcu **rht_bucket_insert(
* @member: name of the &struct rhash_head within the hashable struct.
*/
#define rht_for_each_entry(tpos, pos, tbl, hash, member) \
rht_for_each_entry_from(tpos, pos, *rht_bucket(tbl, hash), \
rht_for_each_entry_from(tpos, pos, rht_ptr(*rht_bucket(tbl, hash)), \
tbl, hash, member)
/**
@ -365,7 +432,8 @@ static inline struct rhash_head __rcu **rht_bucket_insert(
* remove the loop cursor from the list.
*/
#define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \
for (pos = rht_dereference_bucket(*rht_bucket(tbl, hash), tbl, hash), \
for (pos = rht_dereference_bucket(rht_ptr(*rht_bucket(tbl, hash)), \
tbl, hash), \
next = !rht_is_a_nulls(pos) ? \
rht_dereference_bucket(pos->next, tbl, hash) : NULL; \
(!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
@ -400,8 +468,12 @@ static inline struct rhash_head __rcu **rht_bucket_insert(
* the _rcu mutation primitives such as rhashtable_insert() as long as the
* traversal is guarded by rcu_read_lock().
*/
#define rht_for_each_rcu(pos, tbl, hash) \
rht_for_each_rcu_from(pos, *rht_bucket(tbl, hash), tbl, hash)
#define rht_for_each_rcu(pos, tbl, hash) \
for (({barrier(); }), \
pos = rht_ptr(rht_dereference_bucket_rcu( \
*rht_bucket(tbl, hash), tbl, hash)); \
!rht_is_a_nulls(pos); \
pos = rcu_dereference_raw(pos->next))
/**
* rht_for_each_entry_rcu_from - iterated over rcu hash chain from given head
@ -435,7 +507,8 @@ static inline struct rhash_head __rcu **rht_bucket_insert(
* traversal is guarded by rcu_read_lock().
*/
#define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \
rht_for_each_entry_rcu_from(tpos, pos, *rht_bucket(tbl, hash), \
rht_for_each_entry_rcu_from(tpos, pos, \
rht_ptr(*rht_bucket(tbl, hash)), \
tbl, hash, member)
/**
@ -481,7 +554,7 @@ static inline struct rhash_head *__rhashtable_lookup(
.ht = ht,
.key = key,
};
struct rhash_head __rcu * const *head;
struct rhash_lock_head __rcu * const *bkt;
struct bucket_table *tbl;
struct rhash_head *he;
unsigned int hash;
@ -489,9 +562,10 @@ static inline struct rhash_head *__rhashtable_lookup(
tbl = rht_dereference_rcu(ht->tbl, ht);
restart:
hash = rht_key_hashfn(ht, tbl, key, params);
head = rht_bucket(tbl, hash);
bkt = rht_bucket(tbl, hash);
do {
rht_for_each_rcu_from(he, *head, tbl, hash) {
he = rht_ptr(rht_dereference_bucket_rcu(*bkt, tbl, hash));
rht_for_each_rcu_from(he, he, tbl, hash) {
if (params.obj_cmpfn ?
params.obj_cmpfn(&arg, rht_obj(ht, he)) :
rhashtable_compare(&arg, rht_obj(ht, he)))
@ -501,7 +575,7 @@ static inline struct rhash_head *__rhashtable_lookup(
/* An object might have been moved to a different hash chain,
* while we walk along it - better check and retry.
*/
} while (he != RHT_NULLS_MARKER(head));
} while (he != RHT_NULLS_MARKER(bkt));
/* Ensure we see any new tables. */
smp_rmb();
@ -597,10 +671,10 @@ static inline void *__rhashtable_insert_fast(
.ht = ht,
.key = key,
};
struct rhash_lock_head __rcu **bkt;
struct rhash_head __rcu **pprev;
struct bucket_table *tbl;
struct rhash_head *head;
spinlock_t *lock;
unsigned int hash;
int elasticity;
void *data;
@ -609,23 +683,22 @@ static inline void *__rhashtable_insert_fast(
tbl = rht_dereference_rcu(ht->tbl, ht);
hash = rht_head_hashfn(ht, tbl, obj, params);
lock = rht_bucket_lock(tbl, hash);
spin_lock_bh(lock);
elasticity = RHT_ELASTICITY;
bkt = rht_bucket_insert(ht, tbl, hash);
data = ERR_PTR(-ENOMEM);
if (!bkt)
goto out;
pprev = NULL;
rht_lock(tbl, bkt);
if (unlikely(rcu_access_pointer(tbl->future_tbl))) {
slow_path:
spin_unlock_bh(lock);
rht_unlock(tbl, bkt);
rcu_read_unlock();
return rhashtable_insert_slow(ht, key, obj);
}
elasticity = RHT_ELASTICITY;
pprev = rht_bucket_insert(ht, tbl, hash);
data = ERR_PTR(-ENOMEM);
if (!pprev)
goto out;
rht_for_each_from(head, *pprev, tbl, hash) {
rht_for_each_from(head, rht_ptr(*bkt), tbl, hash) {
struct rhlist_head *plist;
struct rhlist_head *list;
@ -641,7 +714,7 @@ static inline void *__rhashtable_insert_fast(
data = rht_obj(ht, head);
if (!rhlist)
goto out;
goto out_unlock;
list = container_of(obj, struct rhlist_head, rhead);
@ -650,9 +723,13 @@ static inline void *__rhashtable_insert_fast(
RCU_INIT_POINTER(list->next, plist);
head = rht_dereference_bucket(head->next, tbl, hash);
RCU_INIT_POINTER(list->rhead.next, head);
rcu_assign_pointer(*pprev, obj);
goto good;
if (pprev) {
rcu_assign_pointer(*pprev, obj);
rht_unlock(tbl, bkt);
} else
rht_assign_unlock(tbl, bkt, obj);
data = NULL;
goto out;
}
if (elasticity <= 0)
@ -660,12 +737,13 @@ static inline void *__rhashtable_insert_fast(
data = ERR_PTR(-E2BIG);
if (unlikely(rht_grow_above_max(ht, tbl)))
goto out;
goto out_unlock;
if (unlikely(rht_grow_above_100(ht, tbl)))
goto slow_path;
head = rht_dereference_bucket(*pprev, tbl, hash);
/* Inserting at head of list makes unlocking free. */
head = rht_ptr(rht_dereference_bucket(*bkt, tbl, hash));
RCU_INIT_POINTER(obj->next, head);
if (rhlist) {
@ -675,20 +753,21 @@ static inline void *__rhashtable_insert_fast(
RCU_INIT_POINTER(list->next, NULL);
}
rcu_assign_pointer(*pprev, obj);
atomic_inc(&ht->nelems);
rht_assign_unlock(tbl, bkt, obj);
if (rht_grow_above_75(ht, tbl))
schedule_work(&ht->run_work);
good:
data = NULL;
out:
spin_unlock_bh(lock);
rcu_read_unlock();
return data;
out_unlock:
rht_unlock(tbl, bkt);
goto out;
}
/**
@ -697,9 +776,9 @@ static inline void *__rhashtable_insert_fast(
* @obj: pointer to hash head inside object
* @params: hash table parameters
*
* Will take a per bucket spinlock to protect against mutual mutations
* Will take the per bucket bitlock to protect against mutual mutations
* on the same bucket. Multiple insertions may occur in parallel unless
* they map to the same bucket lock.
* they map to the same bucket.
*
* It is safe to call this function from atomic context.
*
@ -726,9 +805,9 @@ static inline int rhashtable_insert_fast(
* @list: pointer to hash list head inside object
* @params: hash table parameters
*
* Will take a per bucket spinlock to protect against mutual mutations
* Will take the per bucket bitlock to protect against mutual mutations
* on the same bucket. Multiple insertions may occur in parallel unless
* they map to the same bucket lock.
* they map to the same bucket.
*
* It is safe to call this function from atomic context.
*
@ -749,9 +828,9 @@ static inline int rhltable_insert_key(
* @list: pointer to hash list head inside object
* @params: hash table parameters
*
* Will take a per bucket spinlock to protect against mutual mutations
* Will take the per bucket bitlock to protect against mutual mutations
* on the same bucket. Multiple insertions may occur in parallel unless
* they map to the same bucket lock.
* they map to the same bucket.
*
* It is safe to call this function from atomic context.
*
@ -878,19 +957,20 @@ static inline int __rhashtable_remove_fast_one(
struct rhash_head *obj, const struct rhashtable_params params,
bool rhlist)
{
struct rhash_lock_head __rcu **bkt;
struct rhash_head __rcu **pprev;
struct rhash_head *he;
spinlock_t * lock;
unsigned int hash;
int err = -ENOENT;
hash = rht_head_hashfn(ht, tbl, obj, params);
lock = rht_bucket_lock(tbl, hash);
bkt = rht_bucket_var(tbl, hash);
if (!bkt)
return -ENOENT;
pprev = NULL;
rht_lock(tbl, bkt);
spin_lock_bh(lock);
pprev = rht_bucket_var(tbl, hash);
rht_for_each_from(he, *pprev, tbl, hash) {
rht_for_each_from(he, rht_ptr(*bkt), tbl, hash) {
struct rhlist_head *list;
list = container_of(he, struct rhlist_head, rhead);
@ -930,12 +1010,17 @@ static inline int __rhashtable_remove_fast_one(
}
}
rcu_assign_pointer(*pprev, obj);
break;
if (pprev) {
rcu_assign_pointer(*pprev, obj);
rht_unlock(tbl, bkt);
} else {
rht_assign_unlock(tbl, bkt, obj);
}
goto unlocked;
}
spin_unlock_bh(lock);
rht_unlock(tbl, bkt);
unlocked:
if (err > 0) {
atomic_dec(&ht->nelems);
if (unlikely(ht->p.automatic_shrinking &&
@ -1024,9 +1109,9 @@ static inline int __rhashtable_replace_fast(
struct rhash_head *obj_old, struct rhash_head *obj_new,
const struct rhashtable_params params)
{
struct rhash_lock_head __rcu **bkt;
struct rhash_head __rcu **pprev;
struct rhash_head *he;
spinlock_t *lock;
unsigned int hash;
int err = -ENOENT;
@ -1037,25 +1122,33 @@ static inline int __rhashtable_replace_fast(
if (hash != rht_head_hashfn(ht, tbl, obj_new, params))
return -EINVAL;
lock = rht_bucket_lock(tbl, hash);
bkt = rht_bucket_var(tbl, hash);
if (!bkt)
return -ENOENT;
spin_lock_bh(lock);
pprev = NULL;
rht_lock(tbl, bkt);
pprev = rht_bucket_var(tbl, hash);
rht_for_each_from(he, *pprev, tbl, hash) {
rht_for_each_from(he, rht_ptr(*bkt), tbl, hash) {
if (he != obj_old) {
pprev = &he->next;
continue;
}
rcu_assign_pointer(obj_new->next, obj_old->next);
rcu_assign_pointer(*pprev, obj_new);
if (pprev) {
rcu_assign_pointer(*pprev, obj_new);
rht_unlock(tbl, bkt);
} else {
rht_assign_unlock(tbl, bkt, obj_new);
}
err = 0;
break;
goto unlocked;
}
spin_unlock_bh(lock);
rht_unlock(tbl, bkt);
unlocked:
return err;
}

1
ipc/util.c
View File

@ -101,7 +101,6 @@ static const struct rhashtable_params ipc_kht_params = {
.head_offset = offsetof(struct kern_ipc_perm, khtnode),
.key_offset = offsetof(struct kern_ipc_perm, key),
.key_len = FIELD_SIZEOF(struct kern_ipc_perm, key),
.locks_mul = 1,
.automatic_shrinking = true,
};

159
lib/rhashtable.c
View File

@ -31,11 +31,10 @@
#define HASH_DEFAULT_SIZE 64UL
#define HASH_MIN_SIZE 4U
#define BUCKET_LOCKS_PER_CPU 32UL
union nested_table {
union nested_table __rcu *table;
struct rhash_head __rcu *bucket;
struct rhash_lock_head __rcu *bucket;
};
static u32 head_hashfn(struct rhashtable *ht,
@ -56,9 +55,11 @@ EXPORT_SYMBOL_GPL(lockdep_rht_mutex_is_held);
int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash)
{
spinlock_t *lock = rht_bucket_lock(tbl, hash);
return (debug_locks) ? lockdep_is_held(lock) : 1;
if (!debug_locks)
return 1;
if (unlikely(tbl->nest))
return 1;
return bit_spin_is_locked(1, (unsigned long *)&tbl->buckets[hash]);
}
EXPORT_SYMBOL_GPL(lockdep_rht_bucket_is_held);
#else
@ -104,7 +105,6 @@ static void bucket_table_free(const struct bucket_table *tbl)
if (tbl->nest)
nested_bucket_table_free(tbl);
free_bucket_spinlocks(tbl->locks);
kvfree(tbl);
}
@ -131,9 +131,11 @@ static union nested_table *nested_table_alloc(struct rhashtable *ht,
INIT_RHT_NULLS_HEAD(ntbl[i].bucket);
}
rcu_assign_pointer(*prev, ntbl);
return ntbl;
if (cmpxchg(prev, NULL, ntbl) == NULL)
return ntbl;
/* Raced with another thread. */
kfree(ntbl);
return rcu_dereference(*prev);
}
static struct bucket_table *nested_bucket_table_alloc(struct rhashtable *ht,
@ -169,8 +171,9 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
gfp_t gfp)
{
struct bucket_table *tbl = NULL;
size_t size, max_locks;
size_t size;
int i;
static struct lock_class_key __key;
size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]);
tbl = kvzalloc(size, gfp);
@ -185,18 +188,10 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
if (tbl == NULL)
return NULL;
lockdep_init_map(&tbl->dep_map, "rhashtable_bucket", &__key, 0);
tbl->size = size;
max_locks = size >> 1;
if (tbl->nest)
max_locks = min_t(size_t, max_locks, 1U << tbl->nest);
if (alloc_bucket_spinlocks(&tbl->locks, &tbl->locks_mask, max_locks,
ht->p.locks_mul, gfp) < 0) {
bucket_table_free(tbl);
return NULL;
}
rcu_head_init(&tbl->rcu);
INIT_LIST_HEAD(&tbl->walkers);
@ -221,14 +216,15 @@ static struct bucket_table *rhashtable_last_table(struct rhashtable *ht,
return new_tbl;
}
static int rhashtable_rehash_one(struct rhashtable *ht, unsigned int old_hash)
static int rhashtable_rehash_one(struct rhashtable *ht,
struct rhash_lock_head __rcu **bkt,
unsigned int old_hash)
{
struct bucket_table *old_tbl = rht_dereference(ht->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;
spinlock_t *new_bucket_lock;
struct rhash_head **pprev = NULL;
unsigned int new_hash;
if (new_tbl->nest)
@ -236,7 +232,7 @@ static int rhashtable_rehash_one(struct rhashtable *ht, unsigned int old_hash)
err = -ENOENT;
rht_for_each(entry, old_tbl, old_hash) {
rht_for_each_from(entry, rht_ptr(*bkt), old_tbl, old_hash) {
err = 0;
next = rht_dereference_bucket(entry->next, old_tbl, old_hash);
@ -251,18 +247,20 @@ static int rhashtable_rehash_one(struct rhashtable *ht, unsigned int old_hash)
new_hash = head_hashfn(ht, new_tbl, entry);
new_bucket_lock = rht_bucket_lock(new_tbl, new_hash);
rht_lock_nested(new_tbl, &new_tbl->buckets[new_hash], SINGLE_DEPTH_NESTING);
spin_lock_nested(new_bucket_lock, SINGLE_DEPTH_NESTING);
head = rht_dereference_bucket(new_tbl->buckets[new_hash],
new_tbl, new_hash);
head = rht_ptr(rht_dereference_bucket(new_tbl->buckets[new_hash],
new_tbl, new_hash));
RCU_INIT_POINTER(entry->next, head);
rcu_assign_pointer(new_tbl->buckets[new_hash], entry);
spin_unlock(new_bucket_lock);
rht_assign_unlock(new_tbl, &new_tbl->buckets[new_hash], entry);
rcu_assign_pointer(*pprev, next);
if (pprev)
rcu_assign_pointer(*pprev, next);
else
/* Need to preserved the bit lock. */
rcu_assign_pointer(*bkt, rht_ptr_locked(next));
out:
return err;
@ -272,19 +270,19 @@ static int rhashtable_rehash_chain(struct rhashtable *ht,
unsigned int old_hash)
{
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
spinlock_t *old_bucket_lock;
struct rhash_lock_head __rcu **bkt = rht_bucket_var(old_tbl, old_hash);
int err;
old_bucket_lock = rht_bucket_lock(old_tbl, old_hash);
if (!bkt)
return 0;
rht_lock(old_tbl, bkt);
spin_lock_bh(old_bucket_lock);
while (!(err = rhashtable_rehash_one(ht, old_hash)))
while (!(err = rhashtable_rehash_one(ht, bkt, old_hash)))
;
if (err == -ENOENT)
err = 0;
spin_unlock_bh(old_bucket_lock);
rht_unlock(old_tbl, bkt);
return err;
}
@ -481,6 +479,7 @@ static int rhashtable_insert_rehash(struct rhashtable *ht,
}
static void *rhashtable_lookup_one(struct rhashtable *ht,
struct rhash_lock_head __rcu **bkt,
struct bucket_table *tbl, unsigned int hash,
const void *key, struct rhash_head *obj)
{
@ -488,13 +487,12 @@ static void *rhashtable_lookup_one(struct rhashtable *ht,
.ht = ht,
.key = key,
};
struct rhash_head __rcu **pprev;
struct rhash_head **pprev = NULL;
struct rhash_head *head;
int elasticity;
elasticity = RHT_ELASTICITY;
pprev = rht_bucket_var(tbl, hash);
rht_for_each_from(head, *pprev, tbl, hash) {
rht_for_each_from(head, rht_ptr(*bkt), tbl, hash) {
struct rhlist_head *list;
struct rhlist_head *plist;
@ -516,7 +514,11 @@ static void *rhashtable_lookup_one(struct rhashtable *ht,
RCU_INIT_POINTER(list->next, plist);
head = rht_dereference_bucket(head->next, tbl, hash);
RCU_INIT_POINTER(list->rhead.next, head);
rcu_assign_pointer(*pprev, obj);
if (pprev)
rcu_assign_pointer(*pprev, obj);
else
/* Need to preserve the bit lock */
rcu_assign_pointer(*bkt, rht_ptr_locked(obj));
return NULL;
}
@ -528,12 +530,12 @@ static void *rhashtable_lookup_one(struct rhashtable *ht,
}
static struct bucket_table *rhashtable_insert_one(struct rhashtable *ht,
struct rhash_lock_head __rcu **bkt,
struct bucket_table *tbl,
unsigned int hash,
struct rhash_head *obj,
void *data)
{
struct rhash_head __rcu **pprev;
struct bucket_table *new_tbl;
struct rhash_head *head;
@ -556,11 +558,7 @@ static struct bucket_table *rhashtable_insert_one(struct rhashtable *ht,
if (unlikely(rht_grow_above_100(ht, tbl)))
return ERR_PTR(-EAGAIN);
pprev = rht_bucket_insert(ht, tbl, hash);
if (!pprev)
return ERR_PTR(-ENOMEM);
head = rht_dereference_bucket(*pprev, tbl, hash);
head = rht_ptr(rht_dereference_bucket(*bkt, tbl, hash));
RCU_INIT_POINTER(obj->next, head);
if (ht->rhlist) {
@ -570,7 +568,10 @@ static struct bucket_table *rhashtable_insert_one(struct rhashtable *ht,
RCU_INIT_POINTER(list->next, NULL);
}
rcu_assign_pointer(*pprev, obj);
/* bkt is always the head of the list, so it holds
* the lock, which we need to preserve
*/
rcu_assign_pointer(*bkt, rht_ptr_locked(obj));
atomic_inc(&ht->nelems);
if (rht_grow_above_75(ht, tbl))
@ -584,6 +585,7 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key,
{
struct bucket_table *new_tbl;
struct bucket_table *tbl;
struct rhash_lock_head __rcu **bkt;
unsigned int hash;
void *data;
@ -592,14 +594,25 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key,
do {
tbl = new_tbl;
hash = rht_head_hashfn(ht, tbl, obj, ht->p);
spin_lock_bh(rht_bucket_lock(tbl, hash));
if (rcu_access_pointer(tbl->future_tbl))
/* Failure is OK */
bkt = rht_bucket_var(tbl, hash);
else
bkt = rht_bucket_insert(ht, tbl, hash);
if (bkt == NULL) {
new_tbl = rht_dereference_rcu(tbl->future_tbl, ht);
data = ERR_PTR(-EAGAIN);
} else {
rht_lock(tbl, bkt);
data = rhashtable_lookup_one(ht, bkt, tbl,
hash, key, obj);
new_tbl = rhashtable_insert_one(ht, bkt, tbl,
hash, obj, data);
if (PTR_ERR(new_tbl) != -EEXIST)
data = ERR_CAST(new_tbl);
data = rhashtable_lookup_one(ht, tbl, hash, key, obj);
new_tbl = rhashtable_insert_one(ht, tbl, hash, obj, data);
if (PTR_ERR(new_tbl) != -EEXIST)
data = ERR_CAST(new_tbl);
spin_unlock_bh(rht_bucket_lock(tbl, hash));
rht_unlock(tbl, bkt);
}
} while (!IS_ERR_OR_NULL(new_tbl));
if (PTR_ERR(data) == -EAGAIN)
@ -1026,11 +1039,6 @@ int rhashtable_init(struct rhashtable *ht,
size = rounded_hashtable_size(&ht->p);
if (params->locks_mul)
ht->p.locks_mul = roundup_pow_of_two(params->locks_mul);
else
ht->p.locks_mul = BUCKET_LOCKS_PER_CPU;
ht->key_len = ht->p.key_len;
if (!params->hashfn) {
ht->p.hashfn = jhash;
@ -1132,7 +1140,7 @@ void rhashtable_free_and_destroy(struct rhashtable *ht,
struct rhash_head *pos, *next;
cond_resched();
for (pos = rht_dereference(*rht_bucket(tbl, i), ht),
for (pos = rht_ptr(rht_dereference(*rht_bucket(tbl, i), ht)),
next = !rht_is_a_nulls(pos) ?
rht_dereference(pos->next, ht) : NULL;
!rht_is_a_nulls(pos);
@ -1159,11 +1167,10 @@ void rhashtable_destroy(struct rhashtable *ht)
}
EXPORT_SYMBOL_GPL(rhashtable_destroy);
struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,
unsigned int hash)
struct rhash_lock_head __rcu **__rht_bucket_nested(const struct bucket_table *tbl,
unsigned int hash)
{
const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
static struct rhash_head __rcu *rhnull;
unsigned int index = hash & ((1 << tbl->nest) - 1);
unsigned int size = tbl->size >> tbl->nest;
unsigned int subhash = hash;
@ -1181,20 +1188,28 @@ struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,
subhash >>= shift;
}
if (!ntbl) {
if (!rhnull)
INIT_RHT_NULLS_HEAD(rhnull);
return &rhnull;
}
if (!ntbl)
return NULL;
return &ntbl[subhash].bucket;
}
EXPORT_SYMBOL_GPL(__rht_bucket_nested);
struct rhash_lock_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,
unsigned int hash)
{
static struct rhash_lock_head __rcu *rhnull;
if (!rhnull)
INIT_RHT_NULLS_HEAD(rhnull);
return __rht_bucket_nested(tbl, hash) ?: &rhnull;
}
EXPORT_SYMBOL_GPL(rht_bucket_nested);
struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
struct bucket_table *tbl,
unsigned int hash)
struct rhash_lock_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
struct bucket_table *tbl,
unsigned int hash)
{
const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
unsigned int index = hash & ((1 << tbl->nest) - 1);

2
lib/test_rhashtable.c
View File

@ -500,7 +500,7 @@ static unsigned int __init print_ht(struct rhltable *rhlt)
struct rhash_head *pos, *next;
struct test_obj_rhl *p;
pos = rht_dereference(tbl->buckets[i], ht);
pos = rht_ptr(rht_dereference(tbl->buckets[i], ht));
next = !rht_is_a_nulls(pos) ? rht_dereference(pos->next, ht) : NULL;
if (!rht_is_a_nulls(pos)) {

1
net/bridge/br_fdb.c
View File

@ -33,7 +33,6 @@ static const struct rhashtable_params br_fdb_rht_params = {
.key_offset = offsetof(struct net_bridge_fdb_entry, key),
.key_len = sizeof(struct net_bridge_fdb_key),
.automatic_shrinking = true,
.locks_mul = 1,
};
static struct kmem_cache *br_fdb_cache __read_mostly;

1
net/bridge/br_multicast.c
View File

@ -44,7 +44,6 @@ static const struct rhashtable_params br_mdb_rht_params = {
.key_offset = offsetof(struct net_bridge_mdb_entry, addr),
.key_len = sizeof(struct br_ip),
.automatic_shrinking = true,
.locks_mul = 1,
};
static void br_multicast_start_querier(struct net_bridge *br,

1
net/bridge/br_vlan.c
View File

@ -21,7 +21,6 @@ static const struct rhashtable_params br_vlan_rht_params = {
.key_offset = offsetof(struct net_bridge_vlan, vid),
.key_len = sizeof(u16),
.nelem_hint = 3,
.locks_mul = 1,
.max_size = VLAN_N_VID,
.obj_cmpfn = br_vlan_cmp,
.automatic_shrinking = true,

1
net/bridge/br_vlan_tunnel.c
View File

@ -34,7 +34,6 @@ static const struct rhashtable_params br_vlan_tunnel_rht_params = {
.key_offset = offsetof(struct net_bridge_vlan, tinfo.tunnel_id),
.key_len = sizeof(__be64),
.nelem_hint = 3,
.locks_mul = 1,
.obj_cmpfn = br_vlan_tunid_cmp,
.automatic_shrinking = true,
};

1
net/ipv4/ipmr.c
View File

@ -373,7 +373,6 @@ static const struct rhashtable_params ipmr_rht_params = {
.key_offset = offsetof(struct mfc_cache, cmparg),
.key_len = sizeof(struct mfc_cache_cmp_arg),
.nelem_hint = 3,
.locks_mul = 1,
.obj_cmpfn = ipmr_hash_cmp,
.automatic_shrinking = true,
};

1
net/ipv6/ip6mr.c
View File

@ -355,7 +355,6 @@ static const struct rhashtable_params ip6mr_rht_params = {
.key_offset = offsetof(struct mfc6_cache, cmparg),
.key_len = sizeof(struct mfc6_cache_cmp_arg),
.nelem_hint = 3,
.locks_mul = 1,
.obj_cmpfn = ip6mr_hash_cmp,
.automatic_shrinking = true,
};

1
net/netfilter/nf_tables_api.c
View File

@ -53,7 +53,6 @@ static const struct rhashtable_params nft_chain_ht_params = {
.hashfn = nft_chain_hash,
.obj_hashfn = nft_chain_hash_obj,
.obj_cmpfn = nft_chain_hash_cmp,
.locks_mul = 1,
.automatic_shrinking = true,
};