From: Kaitao Cheng <[email protected]> Extend the refcounted_kptr test: add a node to both an rbtree and a list, retrieve the node from the rbtree to obtain the node pointer, then add a new node after the first in the list, and finally use bpf_list_del to remove both nodes.
The test asserts that the list is non-empty after insert, asserts the first and last nodes after bpf_list_add, and asserts that the list is empty after removing both nodes. To verify the validity of bpf_list_del/add, the test also expects the verifier to reject calls to bpf_list_del/add made without holding the spin_lock. Signed-off-by: Kaitao Cheng <[email protected]> --- .../testing/selftests/bpf/bpf_experimental.h | 16 ++ .../selftests/bpf/progs/refcounted_kptr.c | 140 ++++++++++++++++++ 2 files changed, 156 insertions(+) diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h index 4b7210c318dd..005ca9d84677 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -85,6 +85,22 @@ extern int bpf_list_push_back_impl(struct bpf_list_head *head, /* Convenience macro to wrap over bpf_list_push_back_impl */ #define bpf_list_push_back(head, node) bpf_list_push_back_impl(head, node, NULL, 0) +/* Description + * Insert 'new' after 'prev' in the BPF linked list with head 'head'. + * The bpf_spin_lock protecting the list must be held. 'prev' must already + * be in that list; 'new' must not be in any list. The 'meta' and 'off' + * parameters are rewritten by the verifier, no need for BPF programs to + * set them. + * Returns + * 0 on success, -EINVAL if head is NULL, prev is not in the list with head, + * or new is already in a list. + */ +extern int bpf_list_add_impl(struct bpf_list_head *head, struct bpf_list_node *new, + struct bpf_list_node *prev, void *meta, __u64 off) __ksym; + +/* Convenience macro to wrap over bpf_list_add_impl */ +#define bpf_list_add(head, new, prev) bpf_list_add_impl(head, new, prev, NULL, 0) + /* Description * Remove the entry at the beginning of the BPF linked list. * Returns diff --git a/tools/testing/selftests/bpf/progs/refcounted_kptr.c b/tools/testing/selftests/bpf/progs/refcounted_kptr.c index 1aca85d86aeb..c2defa991acd 100644 --- a/tools/testing/selftests/bpf/progs/refcounted_kptr.c +++ b/tools/testing/selftests/bpf/progs/refcounted_kptr.c @@ -367,6 +367,146 @@ long insert_rbtree_and_stash__del_tree_##rem_tree(void *ctx) \ INSERT_STASH_READ(true, "insert_stash_read: remove from tree"); INSERT_STASH_READ(false, "insert_stash_read: don't remove from tree"); +/* + * Insert one node in tree and list, remove it from tree, add a second node + * after it with bpf_list_add, check bpf_list_is_first/is_last/empty, then + * remove both nodes from list via bpf_list_del. + */ +SEC("tc") +__description("list_add_del_and_check: test bpf_list_add/del/is_first/is_last/empty") +__success __retval(0) +long list_add_del_and_check(void *ctx) +{ + long err = 0; + struct bpf_rb_node *rb; + struct bpf_list_node *l_node, *l_node_ref; + struct node_data *n_rb, *n_new, *n_new_ref; + + err = __insert_in_tree_and_list(&head, &root, &lock); + if (err) + return err; + + bpf_spin_lock(&lock); + /* Test1: bpf_list_empty */ + if (bpf_list_empty(&head)) { + bpf_spin_unlock(&lock); + return -4; + } + + rb = bpf_rbtree_first(&root); + if (!rb) { + bpf_spin_unlock(&lock); + return -5; + } + + rb = bpf_rbtree_remove(&root, rb); + bpf_spin_unlock(&lock); + if (!rb) + return -6; + + n_rb = container_of(rb, struct node_data, r); + n_new = bpf_obj_new(typeof(*n_new)); + if (!n_new) { + bpf_obj_drop(n_rb); + return -7; + } + n_new_ref = bpf_refcount_acquire(n_new); + if (!n_new_ref) { + bpf_obj_drop(n_rb); + bpf_obj_drop(n_new); + return -8; + } + + bpf_spin_lock(&lock); + /* Test2: bpf_list_add */ + if (bpf_list_add(&head, &n_new->l, &n_rb->l)) { + bpf_spin_unlock(&lock); + bpf_obj_drop(n_rb); + bpf_obj_drop(n_new_ref); + return -9; + } + + /* Test3: bpf_list_is_first/is_last */ + if (!bpf_list_is_first(&head, &n_rb->l) || + !bpf_list_is_last(&head, &n_new_ref->l)) { + bpf_spin_unlock(&lock); + bpf_obj_drop(n_rb); + bpf_obj_drop(n_new_ref); + return -10; + } + + /* Test4: bpf_list_del */ + l_node = bpf_list_del(&head, &n_rb->l); + l_node_ref = bpf_list_del(&head, &n_new_ref->l); + bpf_spin_unlock(&lock); + bpf_obj_drop(n_rb); + bpf_obj_drop(n_new_ref); + + if (l_node) + bpf_obj_drop(container_of(l_node, struct node_data, l)); + else + err = -11; + + if (l_node_ref) + bpf_obj_drop(container_of(l_node_ref, struct node_data, l)); + else + err = -12; + + bpf_spin_lock(&lock); + /* Test5: bpf_list_empty */ + if (!bpf_list_empty(&head)) + err = -13; + bpf_spin_unlock(&lock); + return err; +} + +SEC("?tc") +__failure __msg("bpf_spin_lock at off=32 must be held for bpf_list_head") +long list_del_without_lock_fail(void *ctx) +{ + struct bpf_rb_node *rb; + struct bpf_list_node *l; + struct node_data *n; + + bpf_spin_lock(&lock); + rb = bpf_rbtree_first(&root); + bpf_spin_unlock(&lock); + if (!rb) + return -1; + + n = container_of(rb, struct node_data, r); + /* Error case: delete list node without holding lock */ + l = bpf_list_del(&head, &n->l); + if (!l) + return -2; + bpf_obj_drop(container_of(l, struct node_data, l)); + + return 0; +} + +SEC("?tc") +__failure __msg("bpf_spin_lock at off=32 must be held for bpf_list_head") +long list_add_without_lock_fail(void *ctx) +{ + struct bpf_rb_node *rb; + struct bpf_list_node *l; + struct node_data *n; + + bpf_spin_lock(&lock); + rb = bpf_rbtree_first(&root); + l = bpf_list_front(&head); + bpf_spin_unlock(&lock); + if (!rb || !l) + return -1; + + n = container_of(l, struct node_data, l); + /* Error case: add list node without holding lock */ + if (bpf_list_add(&head, &n->l, l)) + return -2; + + return 0; +} + SEC("tc") __success long rbtree_refcounted_node_ref_escapes(void *ctx) -- 2.50.1 (Apple Git-155)
