From 97a6ec4ac021f7fbec05c15a3aa0c4aaf0461af5 Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Mon, 4 Dec 2017 10:31:41 -0800 Subject: rhashtable: Change rhashtable_walk_start to return void Most callers of rhashtable_walk_start don't care about a resize event which is indicated by a return value of -EAGAIN. So calls to rhashtable_walk_start are wrapped wih code to ignore -EAGAIN. Something like this is common: ret = rhashtable_walk_start(rhiter); if (ret && ret != -EAGAIN) goto out; Since zero and -EAGAIN are the only possible return values from the function this check is pointless. The condition never evaluates to true. This patch changes rhashtable_walk_start to return void. This simplifies code for the callers that ignore -EAGAIN. For the few cases where the caller cares about the resize event, particularly where the table can be walked in mulitple parts for netlink or seq file dump, the function rhashtable_walk_start_check has been added that returns -EAGAIN on a resize event. Signed-off-by: Tom Herbert Acked-by: Herbert Xu Signed-off-by: David S. Miller --- include/linux/rhashtable.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index 361c08e35dbc..13ccc483738d 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -378,7 +378,13 @@ void *rhashtable_insert_slow(struct rhashtable *ht, const void *key, void rhashtable_walk_enter(struct rhashtable *ht, struct rhashtable_iter *iter); void rhashtable_walk_exit(struct rhashtable_iter *iter); -int rhashtable_walk_start(struct rhashtable_iter *iter) __acquires(RCU); +int rhashtable_walk_start_check(struct rhashtable_iter *iter) __acquires(RCU); + +static inline void rhashtable_walk_start(struct rhashtable_iter *iter) +{ + (void)rhashtable_walk_start_check(iter); +} + void *rhashtable_walk_next(struct rhashtable_iter *iter); void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU); -- cgit v1.2.3 From 2db54b475ae918d274bfc276416c384ba95e9f94 Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Mon, 4 Dec 2017 10:31:42 -0800 Subject: rhashtable: Add rhastable_walk_peek This function is like rhashtable_walk_next except that it only returns the current element in the inter and does not advance the iter. This patch also creates __rhashtable_walk_find_next. It finds the next element in the table when the entry cached in iter is NULL or at the end of a slot. __rhashtable_walk_find_next is called from rhashtable_walk_next and rhastable_walk_peek. end_of_table is an added field to the iter structure. This indicates that the end of table was reached (walker.tbl being NULL is not a sufficient condition for end of table). Signed-off-by: Tom Herbert Acked-by: Herbert Xu Signed-off-by: David S. Miller --- include/linux/rhashtable.h | 2 + lib/rhashtable.c | 103 ++++++++++++++++++++++++++++++++++++++------- 2 files changed, 89 insertions(+), 16 deletions(-) (limited to 'include/linux') diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index 13ccc483738d..542b1b265ac4 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -207,6 +207,7 @@ struct rhashtable_iter { 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) @@ -386,6 +387,7 @@ static inline void rhashtable_walk_start(struct rhashtable_iter *iter) } void *rhashtable_walk_next(struct rhashtable_iter *iter); +void *rhashtable_walk_peek(struct rhashtable_iter *iter); void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU); void rhashtable_free_and_destroy(struct rhashtable *ht, diff --git a/lib/rhashtable.c b/lib/rhashtable.c index 1935e86ed477..6fc52d82efe6 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -707,6 +707,7 @@ void rhashtable_walk_enter(struct rhashtable *ht, struct rhashtable_iter *iter) iter->p = NULL; iter->slot = 0; iter->skip = 0; + iter->end_of_table = 0; spin_lock(&ht->lock); iter->walker.tbl = @@ -761,7 +762,7 @@ int rhashtable_walk_start_check(struct rhashtable_iter *iter) list_del(&iter->walker.list); spin_unlock(&ht->lock); - if (!iter->walker.tbl) { + if (!iter->walker.tbl && !iter->end_of_table) { iter->walker.tbl = rht_dereference_rcu(ht->tbl, ht); return -EAGAIN; } @@ -771,18 +772,16 @@ int rhashtable_walk_start_check(struct rhashtable_iter *iter) EXPORT_SYMBOL_GPL(rhashtable_walk_start_check); /** - * rhashtable_walk_next - Return the next object and advance the iterator + * __rhashtable_walk_find_next - Find the next element in a table (or the first + * one in case of a new walk). + * * @iter: Hash table iterator * - * Note that you must call rhashtable_walk_stop when you are finished - * with the walk. + * Returns the found object or NULL when the end of the table is reached. * - * Returns the next object or NULL when the end of the table is reached. - * - * Returns -EAGAIN if resize event occured. Note that the iterator - * will rewind back to the beginning and you may continue to use it. + * Returns -EAGAIN if resize event occurred. */ -void *rhashtable_walk_next(struct rhashtable_iter *iter) +static void *__rhashtable_walk_find_next(struct rhashtable_iter *iter) { struct bucket_table *tbl = iter->walker.tbl; struct rhlist_head *list = iter->list; @@ -790,13 +789,8 @@ void *rhashtable_walk_next(struct rhashtable_iter *iter) struct rhash_head *p = iter->p; bool rhlist = ht->rhlist; - if (p) { - if (!rhlist || !(list = rcu_dereference(list->next))) { - p = rcu_dereference(p->next); - list = container_of(p, struct rhlist_head, rhead); - } - goto next; - } + if (!tbl) + return NULL; for (; iter->slot < tbl->size; iter->slot++) { int skip = iter->skip; @@ -840,12 +834,89 @@ next: iter->slot = 0; iter->skip = 0; return ERR_PTR(-EAGAIN); + } else { + iter->end_of_table = true; } return NULL; } + +/** + * rhashtable_walk_next - Return the next object and advance the iterator + * @iter: Hash table iterator + * + * Note that you must call rhashtable_walk_stop when you are finished + * with the walk. + * + * Returns the next object or NULL when the end of the table is reached. + * + * Returns -EAGAIN if resize event occurred. Note that the iterator + * will rewind back to the beginning and you may continue to use it. + */ +void *rhashtable_walk_next(struct rhashtable_iter *iter) +{ + struct rhlist_head *list = iter->list; + struct rhashtable *ht = iter->ht; + struct rhash_head *p = iter->p; + bool rhlist = ht->rhlist; + + if (p) { + if (!rhlist || !(list = rcu_dereference(list->next))) { + p = rcu_dereference(p->next); + list = container_of(p, struct rhlist_head, rhead); + } + if (!rht_is_a_nulls(p)) { + iter->skip++; + iter->p = p; + iter->list = list; + return rht_obj(ht, rhlist ? &list->rhead : p); + } + + /* At the end of this slot, switch to next one and then find + * next entry from that point. + */ + iter->skip = 0; + iter->slot++; + } + + return __rhashtable_walk_find_next(iter); +} EXPORT_SYMBOL_GPL(rhashtable_walk_next); +/** + * rhashtable_walk_peek - Return the next object but don't advance the iterator + * @iter: Hash table iterator + * + * Returns the next object or NULL when the end of the table is reached. + * + * Returns -EAGAIN if resize event occurred. Note that the iterator + * will rewind back to the beginning and you may continue to use it. + */ +void *rhashtable_walk_peek(struct rhashtable_iter *iter) +{ + struct rhlist_head *list = iter->list; + struct rhashtable *ht = iter->ht; + struct rhash_head *p = iter->p; + + if (p) + return rht_obj(ht, ht->rhlist ? &list->rhead : p); + + /* No object found in current iter, find next one in the table. */ + + if (iter->skip) { + /* A nonzero skip value points to the next entry in the table + * beyond that last one that was found. Decrement skip so + * we find the current value. __rhashtable_walk_find_next + * will restore the original value of skip assuming that + * the table hasn't changed. + */ + iter->skip--; + } + + return __rhashtable_walk_find_next(iter); +} +EXPORT_SYMBOL_GPL(rhashtable_walk_peek); + /** * rhashtable_walk_stop - Finish a hash table walk * @iter: Hash table iterator -- cgit v1.2.3 From 2b86093135d014624f668658e1636f22a3027fc2 Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Mon, 4 Dec 2017 10:31:43 -0800 Subject: rhashtable: abstract out function to get hash Split out most of rht_key_hashfn which is calculating the hash into its own function. This way the hash function can be called separately to get the hash value. Acked-by: Thomas Graf Signed-off-by: Tom Herbert Signed-off-by: David S. Miller --- include/linux/rhashtable.h | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-) (limited to 'include/linux') diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index 542b1b265ac4..c9df2527e0cd 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -240,34 +240,42 @@ static inline unsigned int rht_bucket_index(const struct bucket_table *tbl, return (hash >> RHT_HASH_RESERVED_SPACE) & (tbl->size - 1); } -static inline unsigned int rht_key_hashfn( - struct rhashtable *ht, const struct bucket_table *tbl, - const void *key, const struct rhashtable_params params) +static inline unsigned int rht_key_get_hash(struct rhashtable *ht, + const void *key, const struct rhashtable_params params, + unsigned int hash_rnd) { unsigned int hash; /* params must be equal to ht->p if it isn't constant. */ if (!__builtin_constant_p(params.key_len)) - hash = ht->p.hashfn(key, ht->key_len, tbl->hash_rnd); + hash = ht->p.hashfn(key, ht->key_len, hash_rnd); else if (params.key_len) { unsigned int key_len = params.key_len; if (params.hashfn) - hash = params.hashfn(key, key_len, tbl->hash_rnd); + hash = params.hashfn(key, key_len, hash_rnd); else if (key_len & (sizeof(u32) - 1)) - hash = jhash(key, key_len, tbl->hash_rnd); + hash = jhash(key, key_len, hash_rnd); else - hash = jhash2(key, key_len / sizeof(u32), - tbl->hash_rnd); + hash = jhash2(key, key_len / sizeof(u32), hash_rnd); } else { unsigned int key_len = ht->p.key_len; if (params.hashfn) - hash = params.hashfn(key, key_len, tbl->hash_rnd); + hash = params.hashfn(key, key_len, hash_rnd); else - hash = jhash(key, key_len, tbl->hash_rnd); + hash = jhash(key, key_len, hash_rnd); } + return hash; +} + +static inline unsigned int rht_key_hashfn( + struct rhashtable *ht, const struct bucket_table *tbl, + const void *key, const struct rhashtable_params params) +{ + unsigned int hash = rht_key_get_hash(ht, key, params, tbl->hash_rnd); + return rht_bucket_index(tbl, hash); } -- cgit v1.2.3 From 92f36cca5773cbaa78c46ccf49503964a52da294 Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Mon, 4 Dec 2017 10:31:44 -0800 Subject: spinlock: Add library function to allocate spinlock buckets array Add two new library functions: alloc_bucket_spinlocks and free_bucket_spinlocks. These are used to allocate and free an array of spinlocks that are useful as locks for hash buckets. The interface specifies the maximum number of spinlocks in the array as well as a CPU multiplier to derive the number of spinlocks to allocate. The number allocated is rounded up to a power of two to make the array amenable to hash lookup. Signed-off-by: Tom Herbert Signed-off-by: David S. Miller --- include/linux/spinlock.h | 6 ++++++ lib/Makefile | 2 +- lib/bucket_locks.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 61 insertions(+), 1 deletion(-) create mode 100644 lib/bucket_locks.c (limited to 'include/linux') diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index a39186194cd6..10fd28b118ee 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -414,4 +414,10 @@ extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock); #define atomic_dec_and_lock(atomic, lock) \ __cond_lock(lock, _atomic_dec_and_lock(atomic, lock)) +int alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *lock_mask, + size_t max_size, unsigned int cpu_mult, + gfp_t gfp); + +void free_bucket_spinlocks(spinlock_t *locks); + #endif /* __LINUX_SPINLOCK_H */ diff --git a/lib/Makefile b/lib/Makefile index d11c48ec8ffd..a6c8529dd9b2 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -39,7 +39,7 @@ obj-y += bcd.o div64.o sort.o parser.o debug_locks.o random32.o \ gcd.o lcm.o list_sort.o uuid.o flex_array.o iov_iter.o clz_ctz.o \ bsearch.o find_bit.o llist.o memweight.o kfifo.o \ percpu-refcount.o percpu_ida.o rhashtable.o reciprocal_div.o \ - once.o refcount.o usercopy.o errseq.o + once.o refcount.o usercopy.o errseq.o bucket_locks.o obj-$(CONFIG_STRING_SELFTEST) += test_string.o obj-y += string_helpers.o obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o diff --git a/lib/bucket_locks.c b/lib/bucket_locks.c new file mode 100644 index 000000000000..266a97c5708b --- /dev/null +++ b/lib/bucket_locks.c @@ -0,0 +1,54 @@ +#include +#include +#include +#include +#include + +/* Allocate an array of spinlocks to be accessed by a hash. Two arguments + * indicate the number of elements to allocate in the array. max_size + * gives the maximum number of elements to allocate. cpu_mult gives + * the number of locks per CPU to allocate. The size is rounded up + * to a power of 2 to be suitable as a hash table. + */ + +int alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *locks_mask, + size_t max_size, unsigned int cpu_mult, gfp_t gfp) +{ + spinlock_t *tlocks = NULL; + unsigned int i, size; +#if defined(CONFIG_PROVE_LOCKING) + unsigned int nr_pcpus = 2; +#else + unsigned int nr_pcpus = num_possible_cpus(); +#endif + + if (cpu_mult) { + nr_pcpus = min_t(unsigned int, nr_pcpus, 64UL); + size = min_t(unsigned int, nr_pcpus * cpu_mult, max_size); + } else { + size = max_size; + } + + if (sizeof(spinlock_t) != 0) { + if (gfpflags_allow_blocking(gfp)) + tlocks = kvmalloc(size * sizeof(spinlock_t), gfp); + else + tlocks = kmalloc_array(size, sizeof(spinlock_t), gfp); + if (!tlocks) + return -ENOMEM; + for (i = 0; i < size; i++) + spin_lock_init(&tlocks[i]); + } + + *locks = tlocks; + *locks_mask = size - 1; + + return 0; +} +EXPORT_SYMBOL(alloc_bucket_spinlocks); + +void free_bucket_spinlocks(spinlock_t *locks) +{ + kvfree(locks); +} +EXPORT_SYMBOL(free_bucket_spinlocks); -- cgit v1.2.3