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bpf: allow using bpf_kptr_xchg even if the NON_OWN_REF flag is set

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When traversing an rbtree using bpf_rbtree_left/right, if bpf_kptr_xchg
is used to access the __kptr pointer contained in a node, it currently
requires first removing the node with bpf_rbtree_remove and clearing the
NON_OWN_REF flag, then re-adding the node to the original rbtree with
bpf_rbtree_add after usage. This process significantly degrades rbtree
traversal performance. The patch enables accessing __kptr pointers with
the NON_OWN_REF flag set while holding the lock, eliminating the need
for this remove-read-add sequence.

Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
Link: https://lore.kernel.org/r/20260214124042.62229-3-pilgrimtao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Kaitao Cheng 2026-02-14 20:40:39 +08:00 committed by Alexei Starovoitov
parent 964c074768
commit ee9886c40a
1 changed files with 3 additions and 1 deletions
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4
kernel/bpf/verifier.c
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@ -9309,7 +9309,8 @@ static const struct bpf_reg_types timer_types = { .types = { PTR_TO_MAP_VALUE }
static const struct bpf_reg_types kptr_xchg_dest_types = {
.types = {
PTR_TO_MAP_VALUE,
PTR_TO_BTF_ID | MEM_ALLOC
PTR_TO_BTF_ID | MEM_ALLOC,
PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF,
}
};
static const struct bpf_reg_types dynptr_types = {
@ -9473,6 +9474,7 @@ static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
}
case PTR_TO_BTF_ID | MEM_ALLOC:
case PTR_TO_BTF_ID | MEM_PERCPU | MEM_ALLOC:
case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF:
if (meta->func_id != BPF_FUNC_spin_lock && meta->func_id != BPF_FUNC_spin_unlock &&
meta->func_id != BPF_FUNC_kptr_xchg) {
verifier_bug(env, "unimplemented handling of MEM_ALLOC");