// SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */ #include <vmlinux.h> #include <bpf/bpf_helpers.h> #include "bpf_misc.h" #include "bpf_experimental.h" struct node_data { struct bpf_list_node l; int key; }; #define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8))) private(A) struct bpf_spin_lock glock; private(A) struct bpf_list_head ghead __contains(node_data, l); #define list_entry(ptr, type, member) container_of(ptr, type, member) #define NR_NODES 16 int zero = 0; SEC("syscall") __retval(0) long list_peek(void *ctx) { struct bpf_list_node *l_n; struct node_data *n; int i, err = 0; bpf_spin_lock(&glock); l_n = bpf_list_front(&ghead); bpf_spin_unlock(&glock); if (l_n) return __LINE__; bpf_spin_lock(&glock); l_n = bpf_list_back(&ghead); bpf_spin_unlock(&glock); if (l_n) return __LINE__; for (i = zero; i < NR_NODES && can_loop; i++) { n = bpf_obj_new(typeof(*n)); if (!n) return __LINE__; n->key = i; bpf_spin_lock(&glock); bpf_list_push_back(&ghead, &n->l); bpf_spin_unlock(&glock); } bpf_spin_lock(&glock); l_n = bpf_list_front(&ghead); if (!l_n) { err = __LINE__; goto done; } n = list_entry(l_n, struct node_data, l); if (n->key != 0) { err = __LINE__; goto done; } l_n = bpf_list_back(&ghead); if (!l_n) { err = __LINE__; goto done; } n = list_entry(l_n, struct node_data, l); if (n->key != NR_NODES - 1) { err = __LINE__; goto done; } done: bpf_spin_unlock(&glock); return err; } #define TEST_FB(op, dolock) \ SEC("syscall") \ __failure __msg(MSG) \ long test_##op##_spinlock_##dolock(void *ctx) \ { \ struct bpf_list_node *l_n; \ __u64 jiffies = 0; \ \ if (dolock) \ bpf_spin_lock(&glock); \ l_n = bpf_list_##op(&ghead); \ if (l_n) \ jiffies = bpf_jiffies64(); \ if (dolock) \ bpf_spin_unlock(&glock); \ \ return !!jiffies; \ } #define MSG "call bpf_list_{{(front|back).+}}; R0{{(_w)?}}=ptr_or_null_node_data(id={{[0-9]+}},non_own_ref" TEST_FB(front, true) TEST_FB(back, true) #undef MSG #define MSG "bpf_spin_lock at off=0 must be held for bpf_list_head" TEST_FB(front, false) TEST_FB(back, false) #undef MSG char _license[] SEC("license") = "GPL";