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// 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";
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