diff options
| author | Puranjay Mohan <puranjay@kernel.org> | 2026-08-04 06:45:56 -0700 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2026-08-05 10:44:35 -0700 |
| commit | 39f047682fe3ccc272dbebb6d1ecba8fc1e0d8b4 (patch) | |
| tree | 5d48ee5c76c7da095bd9e63f7ac8a2e2dd1b15fa | |
| parent | e93347704878aa8a54b3154114d13e57e8923e27 (diff) | |
bpf: Inline bpf_iter_num_destroy() as a no-op
Once destroy() returns the stack slot is no longer tracked as iterator
state, so zeroing it is dead work. Make the kfunc a no-op and inline the
call to a single BPF_JA 0 (the fixup can't drop the instruction outright,
so emit a nop; the JITs elide it).
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260804134601.2305303-5-puranjay@kernel.org
| -rw-r--r-- | kernel/bpf/bpf_iter.c | 4 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 4 |
2 files changed, 5 insertions, 3 deletions
diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c index d19f1b2861d2..14a5fdfa0421 100644 --- a/kernel/bpf/bpf_iter.c +++ b/kernel/bpf/bpf_iter.c @@ -818,9 +818,7 @@ __bpf_kfunc int *bpf_iter_num_next(struct bpf_iter_num* it) __bpf_kfunc void bpf_iter_num_destroy(struct bpf_iter_num *it) { - struct bpf_iter_num_kern *s = (void *)it; - - s->cur = s->end = 0; + /* no-op */ } __bpf_kfunc_end_defs(); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 80c3cb654b89..4db151e24355 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20047,6 +20047,10 @@ int bpf_fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, insn_buf[i++] = BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 0); insn_buf[i++] = BPF_MOV64_IMM(BPF_REG_0, 0); *cnt = i; + } else if (desc->func_id == special_kfunc_list[KF_bpf_iter_num_destroy]) { + /* bpf_iter_num_destroy() is a no-op; emit a nop to drop the call */ + insn_buf[0] = BPF_JMP_A(0); + *cnt = 1; } if (env->insn_aux_data[insn_idx].arg_prog) { |