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// SPDX-License-Identifier: GPL-2.0
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
char _license[] SEC("license") = "GPL";
struct {
__uint(type, BPF_MAP_TYPE_RINGBUF);
} ringbuf SEC(".maps");
/* inputs */
int pid = 0;
/* outputs */
long passed = 0;
long discarded = 0;
SEC("fentry/" SYS_PREFIX "sys_getpgid")
int test_ringbuf_write(void *ctx)
{
int *foo, cur_pid = bpf_get_current_pid_tgid() >> 32;
void *sample1, *sample2;
if (cur_pid != pid)
return 0;
sample1 = bpf_ringbuf_reserve(&ringbuf, 0x3000, 0);
if (!sample1)
return 0;
/* first one can pass */
sample2 = bpf_ringbuf_reserve(&ringbuf, 0x3000, 0);
if (!sample2) {
bpf_ringbuf_discard(sample1, 0);
__sync_fetch_and_add(&discarded, 1);
return 0;
}
/* second one must not */
__sync_fetch_and_add(&passed, 1);
foo = sample2 + 4084;
*foo = 256;
bpf_ringbuf_discard(sample1, 0);
bpf_ringbuf_discard(sample2, 0);
return 0;
}
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