From: Mathieu Desnoyers Date: Fri, 24 Aug 2012 17:22:13 +0000 (-0400) Subject: rcuja: implement delete function X-Git-Url: http://git.lttng.org/?a=commitdiff_plain;h=af3cbd45cc33c5e887fe9b6abf4d4ab633e0daad;p=userspace-rcu.git rcuja: implement delete function Signed-off-by: Mathieu Desnoyers --- diff --git a/rcuja/rcuja.c b/rcuja/rcuja.c index ea4c887..6b54219 100644 --- a/rcuja/rcuja.c +++ b/rcuja/rcuja.c @@ -590,35 +590,21 @@ int _ja_node_set_nth(const struct cds_ja_type *type, } static -int ja_linear_node_clear_nth(const struct cds_ja_type *type, +int ja_linear_node_clear_ptr(const struct cds_ja_type *type, struct cds_ja_inode *node, struct cds_ja_shadow_node *shadow_node, - uint8_t n) + struct cds_ja_inode_flag **node_flag_ptr) { uint8_t nr_child; - uint8_t *values, *nr_child_ptr; - struct cds_ja_inode_flag **pointers; - unsigned int i; + uint8_t *nr_child_ptr; assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL); nr_child_ptr = &node->u.data[0]; - dbg_printf("linear clear nth: nr_child_ptr %p\n", nr_child_ptr); + dbg_printf("linear clear ptr: nr_child_ptr %p\n", nr_child_ptr); nr_child = *nr_child_ptr; assert(nr_child <= type->max_linear_child); - values = &node->u.data[1]; - pointers = (struct cds_ja_inode_flag **) align_ptr_size(&values[type->max_linear_child]); - for (i = 0; i < nr_child; i++) { - if (values[i] == n) { - if (pointers[i]) - break; - else - return -ENOENT; - } - } - if (i >= nr_child) - return -ENOENT; if (shadow_node->fallback_removal_count) { shadow_node->fallback_removal_count--; } else { @@ -627,8 +613,8 @@ int ja_linear_node_clear_nth(const struct cds_ja_type *type, return -EFBIG; } } - assert(pointers[i] != NULL); - rcu_assign_pointer(pointers[i], NULL); + assert(*node_flag_ptr != NULL); + rcu_assign_pointer(*node_flag_ptr, NULL); /* * Value and nr_child are never changed (would cause ABA issue). * Instead, we leave the pointer to NULL and recompact the node @@ -637,7 +623,7 @@ int ja_linear_node_clear_nth(const struct cds_ja_type *type, * Only update the shadow node accounting. */ shadow_node->nr_child--; - dbg_printf("linear set nth: %u child, shadow: %u child, for node %p shadow %p\n", + dbg_printf("linear clear ptr: %u child, shadow: %u child, for node %p shadow %p\n", (unsigned int) CMM_LOAD_SHARED(*nr_child_ptr), (unsigned int) shadow_node->nr_child, node, shadow_node); @@ -646,9 +632,10 @@ int ja_linear_node_clear_nth(const struct cds_ja_type *type, } static -int ja_pool_node_clear_nth(const struct cds_ja_type *type, +int ja_pool_node_clear_ptr(const struct cds_ja_type *type, struct cds_ja_inode *node, struct cds_ja_shadow_node *shadow_node, + struct cds_ja_inode_flag **node_flag_ptr, uint8_t n) { struct cds_ja_inode *linear; @@ -656,43 +643,39 @@ int ja_pool_node_clear_nth(const struct cds_ja_type *type, assert(type->type_class == RCU_JA_POOL); linear = (struct cds_ja_inode *) &node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order]; - return ja_linear_node_clear_nth(type, linear, shadow_node, n); + return ja_linear_node_clear_ptr(type, linear, shadow_node, node_flag_ptr); } static -int ja_pigeon_node_clear_nth(const struct cds_ja_type *type, +int ja_pigeon_node_clear_ptr(const struct cds_ja_type *type, struct cds_ja_inode *node, struct cds_ja_shadow_node *shadow_node, - uint8_t n) + struct cds_ja_inode_flag **node_flag_ptr) { - struct cds_ja_inode_flag **ptr; - assert(type->type_class == RCU_JA_PIGEON); - ptr = &((struct cds_ja_inode_flag **) node->u.data)[n]; - if (!*ptr) - return -ENOENT; - rcu_assign_pointer(*ptr, NULL); + rcu_assign_pointer(*node_flag_ptr, NULL); shadow_node->nr_child--; return 0; } /* - * _ja_node_clear_nth: clear nth item within a node. Return an error + * _ja_node_clear_ptr: clear ptr item within a node. Return an error * (negative error value) if it is not found (-ENOENT). */ static -int _ja_node_clear_nth(const struct cds_ja_type *type, +int _ja_node_clear_ptr(const struct cds_ja_type *type, struct cds_ja_inode *node, struct cds_ja_shadow_node *shadow_node, + struct cds_ja_inode_flag **node_flag_ptr, uint8_t n) { switch (type->type_class) { case RCU_JA_LINEAR: - return ja_linear_node_clear_nth(type, node, shadow_node, n); + return ja_linear_node_clear_ptr(type, node, shadow_node, node_flag_ptr); case RCU_JA_POOL: - return ja_pool_node_clear_nth(type, node, shadow_node, n); + return ja_pool_node_clear_ptr(type, node, shadow_node, node_flag_ptr, n); case RCU_JA_PIGEON: - return ja_pigeon_node_clear_nth(type, node, shadow_node, n); + return ja_pigeon_node_clear_ptr(type, node, shadow_node, node_flag_ptr); case RCU_JA_NULL: return -ENOENT; default: @@ -717,11 +700,12 @@ int ja_node_recompact(enum ja_recompact mode, struct cds_ja_inode *old_node, struct cds_ja_shadow_node *shadow_node, struct cds_ja_inode_flag **old_node_flag, uint8_t n, - struct cds_ja_inode_flag *child_node_flag) + struct cds_ja_inode_flag *child_node_flag, + struct cds_ja_inode_flag **nullify_node_flag_ptr) { unsigned int new_type_index; struct cds_ja_inode *new_node; - struct cds_ja_shadow_node *new_shadow_node; + struct cds_ja_shadow_node *new_shadow_node = NULL; const struct cds_ja_type *new_type; struct cds_ja_inode_flag *new_node_flag; int ret; @@ -791,7 +775,7 @@ retry: /* for fallback */ ja_linear_node_get_ith_pos(old_type, old_node, i, &v, &iter); if (!iter) continue; - if (mode == JA_RECOMPACT_DEL && v == n) + if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter) continue; ret = _ja_node_set_nth(new_type, new_node, new_shadow_node, @@ -823,7 +807,7 @@ retry: /* for fallback */ j, &v, &iter); if (!iter) continue; - if (mode == JA_RECOMPACT_DEL && v == n) + if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter) continue; ret = _ja_node_set_nth(new_type, new_node, new_shadow_node, @@ -853,7 +837,7 @@ retry: /* for fallback */ iter = ja_pigeon_node_get_ith_pos(old_type, old_node, i); if (!iter) continue; - if (mode == JA_RECOMPACT_DEL && i == n) + if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter) continue; ret = _ja_node_set_nth(new_type, new_node, new_shadow_node, @@ -903,6 +887,7 @@ end: fallback_toosmall: /* fallback if next pool is too small */ + assert(new_shadow_node); ret = rcuja_shadow_clear(ja->ht, new_node, new_shadow_node, RCUJA_SHADOW_CLEAR_FREE_NODE); assert(!ret); @@ -942,12 +927,12 @@ int ja_node_set_nth(struct cds_ja *ja, case -ENOSPC: /* Not enough space in node, need to recompact. */ ret = ja_node_recompact(JA_RECOMPACT_ADD, ja, type_index, type, node, - shadow_node, node_flag, n, child_node_flag); + shadow_node, node_flag, n, child_node_flag, NULL); break; case -ERANGE: /* Node needs to be recompacted. */ ret = ja_node_recompact(JA_RECOMPACT, ja, type_index, type, node, - shadow_node, node_flag, n, child_node_flag); + shadow_node, node_flag, n, child_node_flag, NULL); break; } return ret; @@ -958,43 +943,47 @@ int ja_node_set_nth(struct cds_ja *ja, * error value otherwise. */ static -int ja_node_clear_nth(struct cds_ja *ja, - struct cds_ja_inode_flag **node_flag, uint8_t n, - struct cds_ja_shadow_node *shadow_node) +int ja_node_clear_ptr(struct cds_ja *ja, + struct cds_ja_inode_flag **node_flag_ptr, /* Pointer to location to nullify */ + struct cds_ja_inode_flag **parent_node_flag_ptr, /* Address of parent ptr in its parent */ + struct cds_ja_shadow_node *shadow_node, /* of parent */ + uint8_t n) { int ret; unsigned int type_index; const struct cds_ja_type *type; struct cds_ja_inode *node; - dbg_printf("ja_node_clear_nth for n=%u, node %p, shadow %p\n", - (unsigned int) n, ja_node_ptr(*node_flag), shadow_node); + dbg_printf("ja_node_clear_ptr for node %p, shadow %p, target ptr %p\n", + ja_node_ptr(*parent_node_flag_ptr), shadow_node, node_flag_ptr); - node = ja_node_ptr(*node_flag); - type_index = ja_node_type(*node_flag); + node = ja_node_ptr(*parent_node_flag_ptr); + type_index = ja_node_type(*parent_node_flag_ptr); type = &ja_types[type_index]; - ret = _ja_node_clear_nth(type, node, shadow_node, n); + ret = _ja_node_clear_ptr(type, node, shadow_node, node_flag_ptr, n); if (ret == -EFBIG) { /* Should to try recompaction. */ ret = ja_node_recompact(JA_RECOMPACT_DEL, ja, type_index, type, node, - shadow_node, node_flag, n, NULL); + shadow_node, parent_node_flag_ptr, n, NULL, + node_flag_ptr); } return ret; } -struct cds_hlist_head *cds_ja_lookup(struct cds_ja *ja, uint64_t key) +struct cds_hlist_head cds_ja_lookup(struct cds_ja *ja, uint64_t key) { unsigned int tree_depth, i; struct cds_ja_inode_flag *node_flag; + struct cds_hlist_head head = { NULL }; if (caa_unlikely(key > ja->key_max)) - return NULL; + return head; tree_depth = ja->tree_depth; node_flag = rcu_dereference(ja->root); /* level 0: root node */ if (!ja_node_ptr(node_flag)) - return NULL; + return head; for (i = 1; i < tree_depth; i++) { uint8_t iter_key; @@ -1005,11 +994,12 @@ struct cds_hlist_head *cds_ja_lookup(struct cds_ja *ja, uint64_t key) dbg_printf("cds_ja_lookup iter key lookup %u finds node_flag %p\n", (unsigned int) iter_key, node_flag); if (!ja_node_ptr(node_flag)) - return NULL; + return head; } /* Last level lookup succeded. We got an actual match. */ - return (struct cds_hlist_head *) node_flag; + head.next = (struct cds_hlist_node *) node_flag; + return head; } /* @@ -1034,8 +1024,7 @@ int ja_attach_node(struct cds_ja *ja, struct cds_ja_node *child_node) { struct cds_ja_shadow_node *shadow_node = NULL, - *parent_shadow_node = NULL, - *iter_shadow_node; + *parent_shadow_node = NULL; struct cds_ja_inode *node = ja_node_ptr(node_flag); struct cds_ja_inode *parent_node = ja_node_ptr(parent_node_flag); struct cds_hlist_head head; @@ -1067,16 +1056,6 @@ int ja_attach_node(struct cds_ja *ja, cds_hlist_add_head_rcu(&child_node->list, &head); iter_node_flag = (struct cds_ja_inode_flag *) head.next; - /* Create shadow node for the leaf node */ - dbg_printf("leaf shadow node creation\n"); - iter_shadow_node = rcuja_shadow_set(ja->ht, - ja_node_ptr(iter_node_flag), NULL); - if (!iter_shadow_node) { - ret = -ENOMEM; - goto check_error; - } - created_nodes[nr_created_nodes++] = iter_node_flag; - for (i = ja->tree_depth; i > (int) level; i--) { uint8_t iter_key; @@ -1144,20 +1123,21 @@ end: } /* - * Lock the hlist head shadow node mutex, and add node to list of - * duplicates. Failure can happen if concurrent removal removes the last - * node with same key before we get the lock. + * Lock the parent containing the hlist head pointer, and add node to list of + * duplicates. Failure can happen if concurrent update changes the + * parent before we get the lock. We return -EAGAIN in that case. * Return 0 on success, negative error value on failure. */ static int ja_chain_node(struct cds_ja *ja, + struct cds_ja_inode_flag *parent_node_flag, struct cds_hlist_head *head, struct cds_ja_node *node) { struct cds_ja_shadow_node *shadow_node; shadow_node = rcuja_shadow_lookup_lock(ja->ht, - (struct cds_ja_inode *) head); + ja_node_ptr(parent_node_flag)); if (!shadow_node) return -EAGAIN; cds_hlist_add_head_rcu(&node->list, head); @@ -1224,7 +1204,8 @@ retry: parent2_node_flag, key, i, new_node); } else { ret = ja_chain_node(ja, - (struct cds_hlist_head *) ja_node_ptr(node_flag), + parent_node_flag, + (struct cds_hlist_head *) node_flag_ptr, new_node); } if (ret == -EAGAIN) @@ -1233,26 +1214,164 @@ end: return ret; } +/* + * Note: there is no need to lookup the pointer address associated with + * each node's nth item after taking the lock: it's already been done by + * cds_ja_del while holding the rcu read-side lock, and our node rules + * ensure that when a match value -> pointer is found in a node, it is + * _NEVER_ changed for that node without recompaction, and recompaction + * reallocates the node. + */ static int ja_detach_node(struct cds_ja *ja, struct cds_ja_inode_flag **snapshot, + struct cds_ja_inode_flag ***snapshot_ptr, + uint8_t *snapshot_n, int nr_snapshot, uint64_t key, struct cds_ja_node *node) { - int ret; + struct cds_ja_shadow_node *shadow_nodes[JA_MAX_DEPTH]; + struct cds_ja_inode_flag **node_flag_ptr = NULL, + *parent_node_flag = NULL, + **parent_node_flag_ptr = NULL; + struct cds_ja_inode_flag *iter_node_flag; + int ret, i, nr_shadow = 0, nr_clear = 0; + uint8_t n; assert(nr_snapshot == ja->tree_depth - 1); + /* + * From the last internal level node going up, get the node + * lock, check if the node has only one child left. If it is the + * case, we continue iterating upward. When we reach a node + * which has more that one child left, we lock the parent, and + * proceed to the node deletion (removing its children too). + */ + for (i = nr_snapshot - 1; i >= 1; i--) { + struct cds_ja_shadow_node *shadow_node; + + shadow_node = rcuja_shadow_lookup_lock(ja->ht, + ja_node_ptr(snapshot[i])); + if (!shadow_node) { + ret = -EAGAIN; + goto end; + } + assert(shadow_node->nr_child > 0); + shadow_nodes[nr_shadow++] = shadow_node; + nr_clear++; + if (i == nr_snapshot - 1) { + /* + * Re-check that last internal node level has + * only one child, else trigger a retry. + */ + if (shadow_node->nr_child != 1) { + ret = -EAGAIN; + goto end; + } + } + if (shadow_node->nr_child > 1 || i == 1) { + /* Lock parent and break */ + shadow_node = rcuja_shadow_lookup_lock(ja->ht, + ja_node_ptr(snapshot[i - 1])); + if (!shadow_node) { + ret = -EAGAIN; + goto end; + } + shadow_nodes[nr_shadow++] = shadow_node; + node_flag_ptr = snapshot_ptr[i]; + n = snapshot_n[i]; + parent_node_flag_ptr = snapshot_ptr[i - 1]; + parent_node_flag = snapshot[i - 1]; + if (i > 1) { + /* + * Lock parent's parent, in case we need + * to recompact parent. + */ + shadow_node = rcuja_shadow_lookup_lock(ja->ht, + ja_node_ptr(snapshot[i - 2])); + if (!shadow_node) { + ret = -EAGAIN; + goto end; + } + shadow_nodes[nr_shadow++] = shadow_node; + } + break; + } + } + + /* + * At this point, we want to delete all nodes in shadow_nodes + * (except the last one, which is either the root or the parent + * of the upmost node with 1 child). OK to as to free lock here, + * because RCU read lock is held, and free only performed in + * call_rcu. + */ + + for (i = 0; i < nr_clear; i++) { + ret = rcuja_shadow_clear(ja->ht, + shadow_nodes[i]->node, + shadow_nodes[i], + RCUJA_SHADOW_CLEAR_FREE_NODE + | RCUJA_SHADOW_CLEAR_FREE_LOCK); + assert(!ret); + } + + iter_node_flag = parent_node_flag; + /* Remove from parent */ + ret = ja_node_clear_ptr(ja, + node_flag_ptr, /* Pointer to location to nullify */ + &iter_node_flag, /* Old new parent ptr in its parent */ + shadow_nodes[nr_clear], /* of parent */ + n); + + /* Update address of parent ptr in its parent */ + rcu_assign_pointer(*parent_node_flag_ptr, iter_node_flag); + +end: + for (i = 0; i < nr_shadow; i++) + rcuja_shadow_unlock(shadow_nodes[i]); + return ret; +} + +static +int ja_unchain_node(struct cds_ja *ja, + struct cds_ja_inode_flag *parent_node_flag, + struct cds_ja_node *node) +{ + struct cds_ja_shadow_node *shadow_node; + int ret = 0; + + shadow_node = rcuja_shadow_lookup_lock(ja->ht, + ja_node_ptr(parent_node_flag)); + if (!shadow_node) + return -EAGAIN; + /* + * Retry if another thread removed all but one of duplicates + * since check. + */ + if (shadow_node->nr_child == 1) { + ret = -EAGAIN; + goto end; + } + cds_hlist_del_rcu(&node->list); +end: + rcuja_shadow_unlock(shadow_node); return ret; } +/* + * Called with RCU read lock held. + */ int cds_ja_del(struct cds_ja *ja, uint64_t key, struct cds_ja_node *node) { unsigned int tree_depth, i; struct cds_ja_inode_flag *snapshot[JA_MAX_DEPTH]; + struct cds_ja_inode_flag **snapshot_ptr[JA_MAX_DEPTH]; + uint8_t snapshot_n[JA_MAX_DEPTH]; struct cds_ja_inode_flag *node_flag; + struct cds_ja_inode_flag **prev_node_flag_ptr; int nr_snapshot = 0; int ret; @@ -1265,8 +1384,11 @@ retry: key, node); /* snapshot for level 0 is only for shadow node lookup */ + snapshot_n[nr_snapshot] = 0; + snapshot_ptr[nr_snapshot] = NULL; snapshot[nr_snapshot++] = (struct cds_ja_inode_flag *) &ja->root; node_flag = rcu_dereference(ja->root); + prev_node_flag_ptr = &ja->root; /* Iterate on all internal levels */ for (i = 1; i < tree_depth; i++) { @@ -1277,13 +1399,20 @@ retry: if (!ja_node_ptr(node_flag)) { return -ENOENT; } - snapshot[nr_snapshot++] = node_flag; iter_key = (uint8_t) (key >> (JA_BITS_PER_BYTE * (tree_depth - i - 1))); + if (nr_snapshot <= 1) + snapshot_n[nr_snapshot] = 0; + else + snapshot_n[nr_snapshot - 1] = iter_key; + + snapshot_ptr[nr_snapshot] = prev_node_flag_ptr; + snapshot[nr_snapshot++] = node_flag; node_flag = ja_node_get_nth(node_flag, - NULL, + &prev_node_flag_ptr, iter_key); - dbg_printf("cds_ja_del iter key lookup %u finds node_flag %p\n", - (unsigned int) iter_key, node_flag); + dbg_printf("cds_ja_del iter key lookup %u finds node_flag %p, prev_node_flag_ptr %p\n", + (unsigned int) iter_key, node_flag, + prev_node_flag_ptr); } /* @@ -1295,22 +1424,32 @@ retry: } else { struct cds_hlist_head *hlist_head; struct cds_hlist_node *hlist_node; - struct cds_ja_node *entry; - int found; + struct cds_ja_node *entry, *match = NULL; + int count = 0; hlist_head = (struct cds_hlist_head *) ja_node_ptr(node_flag); - cds_hlist_for_each_entry(entry, + cds_hlist_for_each_entry_rcu(entry, hlist_node, hlist_head, list) { - if (entry == node) { - found = 1; - break; - } + if (entry == node) + match = entry; + count++; } - if (!found) + if (!match) return -ENOENT; - ret = ja_detach_node(ja, snapshot, nr_snapshot, key, node); + assert(count > 0); + if (count == 1) { + /* + * Removing last of duplicates. + */ + snapshot_ptr[nr_snapshot] = prev_node_flag_ptr; + snapshot[nr_snapshot++] = node_flag; + ret = ja_detach_node(ja, snapshot, snapshot_ptr, + snapshot_n, nr_snapshot, key, node); + } else { + ret = ja_unchain_node(ja, node_flag, entry); + } } if (ret == -EAGAIN) goto retry; diff --git a/tests/test_urcu_ja.c b/tests/test_urcu_ja.c index 7c6190d..d933bae 100644 --- a/tests/test_urcu_ja.c +++ b/tests/test_urcu_ja.c @@ -207,11 +207,11 @@ int test_8bit_key(void) printf("Test #2: successful key lookup (8-bit).\n"); for (key = 0; key < 200; key++) { - struct cds_hlist_head *head; + struct cds_hlist_head head; rcu_read_lock(); head = cds_ja_lookup(test_ja, key); - if (!head) { + if (cds_hlist_empty(&head)) { fprintf(stderr, "Error lookup node %" PRIu64 "\n", key); assert(0); } @@ -220,11 +220,11 @@ int test_8bit_key(void) printf("OK\n"); printf("Test #3: unsuccessful key lookup (8-bit).\n"); for (key = 200; key < 240; key++) { - struct cds_hlist_head *head; + struct cds_hlist_head head; rcu_read_lock(); head = cds_ja_lookup(test_ja, key); - if (head) { + if (!cds_hlist_empty(&head)) { fprintf(stderr, "Error unexpected lookup node %" PRIu64 "\n", key); @@ -277,11 +277,11 @@ int test_16bit_key(void) printf("Test #2: successful key lookup (16-bit).\n"); //for (key = 0; key < 10000; key++) { for (key = 0; key < 65536; key+=256) { - struct cds_hlist_head *head; + struct cds_hlist_head head; rcu_read_lock(); head = cds_ja_lookup(test_ja, key); - if (!head) { + if (cds_hlist_empty(&head)) { fprintf(stderr, "Error lookup node %" PRIu64 "\n", key); assert(0); } @@ -290,11 +290,11 @@ int test_16bit_key(void) printf("OK\n"); printf("Test #3: unsuccessful key lookup (16-bit).\n"); for (key = 11000; key <= 11002; key++) { - struct cds_hlist_head *head; + struct cds_hlist_head head; rcu_read_lock(); head = cds_ja_lookup(test_ja, key); - if (head) { + if (!cds_hlist_empty(&head)) { fprintf(stderr, "Error unexpected lookup node %" PRIu64 "\n", key); @@ -356,11 +356,11 @@ int test_sparse_key(unsigned int bits) printf("Test #2: successful key lookup (%u-bit).\n", bits); zerocount = 0; for (key = 0; key <= max_key && (key != 0 || zerocount < 1); key += 1ULL << (bits - 8)) { - struct cds_hlist_head *head; + struct cds_hlist_head head; rcu_read_lock(); head = cds_ja_lookup(test_ja, key); - if (!head) { + if (cds_hlist_empty(&head)) { fprintf(stderr, "Error lookup node %" PRIu64 "\n", key); assert(0); } @@ -373,11 +373,11 @@ int test_sparse_key(unsigned int bits) printf("Test #3: unsuccessful key lookup (%u-bit).\n", bits); zerocount = 0; for (key = 0; key <= max_key && (key != 0 || zerocount < 1); key += 1ULL << (bits - 8)) { - struct cds_hlist_head *head; + struct cds_hlist_head head; rcu_read_lock(); head = cds_ja_lookup(test_ja, key + 42); - if (head) { + if (!cds_hlist_empty(&head)) { fprintf(stderr, "Error unexpected lookup node %" PRIu64 "\n", key + 42);