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bpf: Introduce the bpf_list_del kfunc.

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Allow users to remove any node from a linked list.

We have added an additional parameter bpf_list_head *head to
bpf_list_del, as the verifier requires the head parameter to
check whether the lock is being held.

Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260521032306.97118-5-kaitao.cheng@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Kaitao Cheng 2026-05-21 11:23:02 +08:00 committed by Alexei Starovoitov
parent 7c8c71591b
commit 187baa1096
2 changed files with 15 additions and 1 deletions
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10
kernel/bpf/helpers.c
View File

@ -2601,6 +2601,15 @@ __bpf_kfunc struct bpf_list_node *bpf_list_pop_back(struct bpf_list_head *head)
return __bpf_list_del(head, h->prev);
}
__bpf_kfunc struct bpf_list_node *bpf_list_del(struct bpf_list_head *head,
struct bpf_list_node *node__nonown_allowed)
{
struct bpf_list_node_kern *kn = (void *)node__nonown_allowed;
/* verifier guarantees node is a list node rather than list head */
return __bpf_list_del(head, &kn->list_head);
}
__bpf_kfunc struct bpf_list_node *bpf_list_front(struct bpf_list_head *head)
{
struct list_head *h = (struct list_head *)head;
@ -4733,6 +4742,7 @@ BTF_ID_FLAGS(func, bpf_list_push_back, KF_IMPLICIT_ARGS)
BTF_ID_FLAGS(func, bpf_list_push_back_impl)
BTF_ID_FLAGS(func, bpf_list_pop_front, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_list_pop_back, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_list_del, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_list_front, KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_list_back, KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_RCU | KF_RET_NULL)

6
kernel/bpf/verifier.c
View File

@ -10961,6 +10961,7 @@ enum special_kfunc_type {
KF_bpf_list_push_back,
KF_bpf_list_pop_front,
KF_bpf_list_pop_back,
KF_bpf_list_del,
KF_bpf_list_front,
KF_bpf_list_back,
KF_bpf_cast_to_kern_ctx,
@ -11029,6 +11030,7 @@ BTF_ID(func, bpf_list_push_back_impl)
BTF_ID(func, bpf_list_push_back)
BTF_ID(func, bpf_list_pop_front)
BTF_ID(func, bpf_list_pop_back)
BTF_ID(func, bpf_list_del)
BTF_ID(func, bpf_list_front)
BTF_ID(func, bpf_list_back)
BTF_ID(func, bpf_cast_to_kern_ctx)
@ -11549,6 +11551,7 @@ static bool is_bpf_list_api_kfunc(u32 btf_id)
return is_bpf_list_push_kfunc(btf_id) ||
btf_id == special_kfunc_list[KF_bpf_list_pop_front] ||
btf_id == special_kfunc_list[KF_bpf_list_pop_back] ||
btf_id == special_kfunc_list[KF_bpf_list_del] ||
btf_id == special_kfunc_list[KF_bpf_list_front] ||
btf_id == special_kfunc_list[KF_bpf_list_back];
}
@ -11671,7 +11674,8 @@ static bool check_kfunc_is_graph_node_api(struct bpf_verifier_env *env,
switch (node_field_type) {
case BPF_LIST_NODE:
ret = is_bpf_list_push_kfunc(kfunc_btf_id);
ret = is_bpf_list_push_kfunc(kfunc_btf_id) ||
kfunc_btf_id == special_kfunc_list[KF_bpf_list_del];
break;
case BPF_RB_NODE:
ret = (is_bpf_rbtree_add_kfunc(kfunc_btf_id) ||