X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=rcuja%2Frcuja-shadow-nodes.c;h=5ef68d58631bd5d7a673496f78e755ce78b97a90;hb=11c5e01644e22c2c3c372da0e93e09a8f43239ac;hp=6094b7ad13a19556145556ab6829e8beccc4e4f5;hpb=195e72d3c13aa84df6d149b342468ff04f200343;p=userspace-rcu.git diff --git a/rcuja/rcuja-shadow-nodes.c b/rcuja/rcuja-shadow-nodes.c index 6094b7a..5ef68d5 100644 --- a/rcuja/rcuja-shadow-nodes.c +++ b/rcuja/rcuja-shadow-nodes.c @@ -24,30 +24,317 @@ #include #include #include - -/* - * The hash table used by judy array updates only for the shadow node - * mapping rely on standard urcu_mb flavor. It does not put any - * requirement on the RCU flavor used by applications using the judy - * array. - */ -#include - #include #include #include #include #include +#include +#include #include "rcuja-internal.h" #include "bitfield.h" +static unsigned long hash_seed; + +/* + * Hash function + * Source: http://burtleburtle.net/bob/c/lookup3.c + * Originally Public Domain + */ + +#define rot(x, k) (((x) << (k)) | ((x) >> (32 - (k)))) + +#define mix(a, b, c) \ +do { \ + a -= c; a ^= rot(c, 4); c += b; \ + b -= a; b ^= rot(a, 6); a += c; \ + c -= b; c ^= rot(b, 8); b += a; \ + a -= c; a ^= rot(c, 16); c += b; \ + b -= a; b ^= rot(a, 19); a += c; \ + c -= b; c ^= rot(b, 4); b += a; \ +} while (0) + +#define final(a, b, c) \ +{ \ + c ^= b; c -= rot(b, 14); \ + a ^= c; a -= rot(c, 11); \ + b ^= a; b -= rot(a, 25); \ + c ^= b; c -= rot(b, 16); \ + a ^= c; a -= rot(c, 4);\ + b ^= a; b -= rot(a, 14); \ + c ^= b; c -= rot(b, 24); \ +} + +static inline __attribute__((unused)) +uint32_t hash_u32( + const uint32_t *k, /* the key, an array of uint32_t values */ + size_t length, /* the length of the key, in uint32_ts */ + uint32_t initval) /* the previous hash, or an arbitrary value */ +{ + uint32_t a, b, c; + + /* Set up the internal state */ + a = b = c = 0xdeadbeef + (((uint32_t) length) << 2) + initval; + + /*----------------------------------------- handle most of the key */ + while (length > 3) { + a += k[0]; + b += k[1]; + c += k[2]; + mix(a, b, c); + length -= 3; + k += 3; + } + + /*----------------------------------- handle the last 3 uint32_t's */ + switch (length) { /* all the case statements fall through */ + case 3: c += k[2]; + case 2: b += k[1]; + case 1: a += k[0]; + final(a, b, c); + case 0: /* case 0: nothing left to add */ + break; + } + /*---------------------------------------------- report the result */ + return c; +} + +static inline +void hashword2( + const uint32_t *k, /* the key, an array of uint32_t values */ + size_t length, /* the length of the key, in uint32_ts */ + uint32_t *pc, /* IN: seed OUT: primary hash value */ + uint32_t *pb) /* IN: more seed OUT: secondary hash value */ +{ + uint32_t a, b, c; + + /* Set up the internal state */ + a = b = c = 0xdeadbeef + ((uint32_t) (length << 2)) + *pc; + c += *pb; + + /*----------------------------------------- handle most of the key */ + while (length > 3) { + a += k[0]; + b += k[1]; + c += k[2]; + mix(a, b, c); + length -= 3; + k += 3; + } + + /*----------------------------------- handle the last 3 uint32_t's */ + switch (length) { /* all the case statements fall through */ + case 3: c += k[2]; + case 2: b += k[1]; + case 1: a += k[0]; + final(a, b, c); + case 0: /* case 0: nothing left to add */ + break; + } + /*---------------------------------------------- report the result */ + *pc = c; + *pb = b; +} + +#if (CAA_BITS_PER_LONG == 32) +static +unsigned long hash_pointer(const void *_key, unsigned long seed) +{ + unsigned int key = (unsigned int) _key; + + return hash_u32(&key, 1, seed); +} +#else +static +unsigned long hash_pointer(const void *_key, unsigned long seed) +{ + union { + uint64_t v64; + uint32_t v32[2]; + } v; + union { + uint64_t v64; + uint32_t v32[2]; + } key; + + v.v64 = (uint64_t) seed; + key.v64 = (uint64_t) _key; + hashword2(key.v32, 2, &v.v32[0], &v.v32[1]); + return v.v64; +} +#endif + +static +int match_pointer(struct cds_lfht_node *node, const void *key) +{ + struct rcu_ja_shadow_node *shadow = + caa_container_of(node, struct rcu_ja_shadow_node, ht_node); + + return (key == shadow->node); +} + +__attribute__((visibility("protected"))) +struct rcu_ja_shadow_node *rcuja_shadow_lookup_lock(struct cds_lfht *ht, + struct rcu_ja_node *node) +{ + struct cds_lfht_iter iter; + struct cds_lfht_node *lookup_node; + struct rcu_ja_shadow_node *shadow_node; + const struct rcu_flavor_struct *flavor; + int ret; + + flavor = cds_lfht_rcu_flavor(ht); + flavor->read_lock(); + cds_lfht_lookup(ht, hash_pointer(node, hash_seed), + match_pointer, node, &iter); + + lookup_node = cds_lfht_iter_get_node(&iter); + if (!lookup_node) { + shadow_node = NULL; + goto rcu_unlock; + } + shadow_node = caa_container_of(lookup_node, + struct rcu_ja_shadow_node, ht_node); + ret = pthread_mutex_lock(shadow_node->lock); + assert(!ret); + if (cds_lfht_is_node_deleted(lookup_node)) { + ret = pthread_mutex_unlock(shadow_node->lock); + assert(!ret); + shadow_node = NULL; + } +rcu_unlock: + flavor->read_unlock(); + return shadow_node; +} + __attribute__((visibility("protected"))) -struct cds_lfht *rcuja_create_ht(void) +void rcuja_shadow_unlock(struct rcu_ja_shadow_node *shadow_node) { - return cds_lfht_new(1, 1, 0, + int ret; + + ret = pthread_mutex_unlock(shadow_node->lock); + assert(!ret); +} + +__attribute__((visibility("protected"))) +int rcuja_shadow_set(struct cds_lfht *ht, + struct rcu_ja_node *new_node, + struct rcu_ja_shadow_node *inherit_from) +{ + struct rcu_ja_shadow_node *shadow_node; + struct cds_lfht_node *ret_node; + const struct rcu_flavor_struct *flavor; + + shadow_node = calloc(sizeof(*shadow_node), 1); + if (!shadow_node) + return -ENOMEM; + + shadow_node->node = new_node; + /* + * Lock can be inherited from previous node at this position. + */ + if (inherit_from) { + shadow_node->lock = inherit_from->lock; + } else { + shadow_node->lock = calloc(sizeof(*shadow_node->lock), 1); + if (!shadow_node->lock) { + free(shadow_node); + return -ENOMEM; + } + pthread_mutex_init(shadow_node->lock, NULL); + } + + flavor = cds_lfht_rcu_flavor(ht); + flavor->read_lock(); + ret_node = cds_lfht_add_unique(ht, + hash_pointer(new_node, hash_seed), + match_pointer, + new_node, + &shadow_node->ht_node); + flavor->read_unlock(); + + if (ret_node != &shadow_node->ht_node) { + free(shadow_node); + return -EEXIST; + } + return 0; +} + +static +void free_shadow_node_and_node(struct rcu_head *head) +{ + struct rcu_ja_shadow_node *shadow_node = + caa_container_of(head, struct rcu_ja_shadow_node, head); + free(shadow_node->node); + free(shadow_node); +} + +static +void free_shadow_node_and_node_and_lock(struct rcu_head *head) +{ + struct rcu_ja_shadow_node *shadow_node = + caa_container_of(head, struct rcu_ja_shadow_node, head); + free(shadow_node->node); + free(shadow_node->lock); + free(shadow_node); +} + +__attribute__((visibility("protected"))) +int rcuja_shadow_clear(struct cds_lfht *ht, + struct rcu_ja_node *node, + unsigned int flags) +{ + struct cds_lfht_iter iter; + struct cds_lfht_node *lookup_node; + struct rcu_ja_shadow_node *shadow_node; + const struct rcu_flavor_struct *flavor; + int ret, lockret; + + flavor = cds_lfht_rcu_flavor(ht); + flavor->read_lock(); + cds_lfht_lookup(ht, hash_pointer(node, hash_seed), + match_pointer, node, &iter); + lookup_node = cds_lfht_iter_get_node(&iter); + if (!lookup_node) { + ret = -ENOENT; + goto rcu_unlock; + } + shadow_node = caa_container_of(lookup_node, + struct rcu_ja_shadow_node, ht_node); + lockret = pthread_mutex_lock(shadow_node->lock); + assert(!lockret); + + /* + * Holding the mutex across deletion, and by also re-checking if + * the node is deleted with mutex held at lookup ensure that we + * don't let RCU JA use a node being removed. + */ + ret = cds_lfht_del(ht, lookup_node); + if (!ret) { + assert(flags & RCUJA_SHADOW_CLEAR_FREE_NODE); + if (flags & RCUJA_SHADOW_CLEAR_FREE_LOCK) { + flavor->update_call_rcu(&shadow_node->head, + free_shadow_node_and_node_and_lock); + } else { + flavor->update_call_rcu(&shadow_node->head, + free_shadow_node_and_node); + } + } + lockret = pthread_mutex_unlock(shadow_node->lock); + assert(!lockret); +rcu_unlock: + flavor->read_unlock(); + + return ret; +} + +__attribute__((visibility("protected"))) +struct cds_lfht *rcuja_create_ht(const struct rcu_flavor_struct *flavor) +{ + return _cds_lfht_new(1, 1, 0, CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, - NULL); + NULL, flavor, NULL); } __attribute__((visibility("protected"))) @@ -58,3 +345,9 @@ void rcuja_delete_ht(struct cds_lfht *ht) ret = cds_lfht_destroy(ht, NULL); assert(!ret); } + +__attribute__((constructor)) +void rcuja_ht_init(void) +{ + hash_seed = (unsigned long) time(NULL); +}