287 lines
7.3 KiB
C
287 lines
7.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2021 Facebook */
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#include <linux/bpf.h>
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#include <time.h>
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#include <errno.h>
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#include <bpf/bpf_helpers.h>
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#include "bpf_tcp_helpers.h"
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char _license[] SEC("license") = "GPL";
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struct hmap_elem {
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int counter;
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struct bpf_timer timer;
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struct bpf_spin_lock lock; /* unused */
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};
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(max_entries, 1000);
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__type(key, int);
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__type(value, struct hmap_elem);
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} hmap SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(map_flags, BPF_F_NO_PREALLOC);
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__uint(max_entries, 1000);
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__type(key, int);
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__type(value, struct hmap_elem);
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} hmap_malloc SEC(".maps");
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struct elem {
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struct bpf_timer t;
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};
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__uint(max_entries, 2);
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__type(key, int);
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__type(value, struct elem);
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} array SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_LRU_HASH);
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__uint(max_entries, 4);
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__type(key, int);
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__type(value, struct elem);
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} lru SEC(".maps");
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__u64 bss_data;
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__u64 err;
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__u64 ok;
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__u64 callback_check = 52;
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__u64 callback2_check = 52;
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#define ARRAY 1
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#define HTAB 2
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#define HTAB_MALLOC 3
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#define LRU 4
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/* callback for array and lru timers */
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static int timer_cb1(void *map, int *key, struct bpf_timer *timer)
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{
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/* increment bss variable twice.
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* Once via array timer callback and once via lru timer callback
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*/
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bss_data += 5;
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/* *key == 0 - the callback was called for array timer.
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* *key == 4 - the callback was called from lru timer.
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*/
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if (*key == ARRAY) {
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struct bpf_timer *lru_timer;
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int lru_key = LRU;
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/* rearm array timer to be called again in ~35 seconds */
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if (bpf_timer_start(timer, 1ull << 35, 0) != 0)
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err |= 1;
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lru_timer = bpf_map_lookup_elem(&lru, &lru_key);
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if (!lru_timer)
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return 0;
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bpf_timer_set_callback(lru_timer, timer_cb1);
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if (bpf_timer_start(lru_timer, 0, 0) != 0)
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err |= 2;
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} else if (*key == LRU) {
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int lru_key, i;
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for (i = LRU + 1;
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i <= 100 /* for current LRU eviction algorithm this number
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* should be larger than ~ lru->max_entries * 2
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*/;
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i++) {
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struct elem init = {};
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/* lru_key cannot be used as loop induction variable
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* otherwise the loop will be unbounded.
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*/
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lru_key = i;
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/* add more elements into lru map to push out current
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* element and force deletion of this timer
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*/
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bpf_map_update_elem(map, &lru_key, &init, 0);
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/* look it up to bump it into active list */
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bpf_map_lookup_elem(map, &lru_key);
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/* keep adding until *key changes underneath,
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* which means that key/timer memory was reused
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*/
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if (*key != LRU)
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break;
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}
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/* check that the timer was removed */
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if (bpf_timer_cancel(timer) != -EINVAL)
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err |= 4;
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ok |= 1;
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}
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return 0;
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}
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SEC("fentry/bpf_fentry_test1")
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int BPF_PROG2(test1, int, a)
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{
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struct bpf_timer *arr_timer, *lru_timer;
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struct elem init = {};
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int lru_key = LRU;
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int array_key = ARRAY;
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arr_timer = bpf_map_lookup_elem(&array, &array_key);
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if (!arr_timer)
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return 0;
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bpf_timer_init(arr_timer, &array, CLOCK_MONOTONIC);
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bpf_map_update_elem(&lru, &lru_key, &init, 0);
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lru_timer = bpf_map_lookup_elem(&lru, &lru_key);
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if (!lru_timer)
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return 0;
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bpf_timer_init(lru_timer, &lru, CLOCK_MONOTONIC);
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bpf_timer_set_callback(arr_timer, timer_cb1);
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bpf_timer_start(arr_timer, 0 /* call timer_cb1 asap */, 0);
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/* init more timers to check that array destruction
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* doesn't leak timer memory.
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*/
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array_key = 0;
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arr_timer = bpf_map_lookup_elem(&array, &array_key);
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if (!arr_timer)
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return 0;
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bpf_timer_init(arr_timer, &array, CLOCK_MONOTONIC);
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return 0;
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}
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/* callback for prealloc and non-prealloca hashtab timers */
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static int timer_cb2(void *map, int *key, struct hmap_elem *val)
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{
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if (*key == HTAB)
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callback_check--;
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else
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callback2_check--;
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if (val->counter > 0 && --val->counter) {
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/* re-arm the timer again to execute after 1 usec */
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bpf_timer_start(&val->timer, 1000, 0);
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} else if (*key == HTAB) {
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struct bpf_timer *arr_timer;
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int array_key = ARRAY;
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/* cancel arr_timer otherwise bpf_fentry_test1 prog
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* will stay alive forever.
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*/
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arr_timer = bpf_map_lookup_elem(&array, &array_key);
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if (!arr_timer)
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return 0;
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if (bpf_timer_cancel(arr_timer) != 1)
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/* bpf_timer_cancel should return 1 to indicate
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* that arr_timer was active at this time
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*/
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err |= 8;
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/* try to cancel ourself. It shouldn't deadlock. */
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if (bpf_timer_cancel(&val->timer) != -EDEADLK)
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err |= 16;
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/* delete this key and this timer anyway.
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* It shouldn't deadlock either.
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*/
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bpf_map_delete_elem(map, key);
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/* in preallocated hashmap both 'key' and 'val' could have been
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* reused to store another map element (like in LRU above),
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* but in controlled test environment the below test works.
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* It's not a use-after-free. The memory is owned by the map.
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*/
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if (bpf_timer_start(&val->timer, 1000, 0) != -EINVAL)
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err |= 32;
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ok |= 2;
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} else {
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if (*key != HTAB_MALLOC)
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err |= 64;
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/* try to cancel ourself. It shouldn't deadlock. */
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if (bpf_timer_cancel(&val->timer) != -EDEADLK)
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err |= 128;
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/* delete this key and this timer anyway.
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* It shouldn't deadlock either.
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*/
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bpf_map_delete_elem(map, key);
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ok |= 4;
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}
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return 0;
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}
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int bpf_timer_test(void)
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{
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struct hmap_elem *val;
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int key = HTAB, key_malloc = HTAB_MALLOC;
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val = bpf_map_lookup_elem(&hmap, &key);
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if (val) {
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if (bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME) != 0)
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err |= 512;
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bpf_timer_set_callback(&val->timer, timer_cb2);
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bpf_timer_start(&val->timer, 1000, 0);
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}
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val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
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if (val) {
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if (bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME) != 0)
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err |= 1024;
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bpf_timer_set_callback(&val->timer, timer_cb2);
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bpf_timer_start(&val->timer, 1000, 0);
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}
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return 0;
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}
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SEC("fentry/bpf_fentry_test2")
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int BPF_PROG2(test2, int, a, int, b)
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{
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struct hmap_elem init = {}, *val;
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int key = HTAB, key_malloc = HTAB_MALLOC;
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init.counter = 10; /* number of times to trigger timer_cb2 */
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bpf_map_update_elem(&hmap, &key, &init, 0);
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val = bpf_map_lookup_elem(&hmap, &key);
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if (val)
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bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME);
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/* update the same key to free the timer */
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bpf_map_update_elem(&hmap, &key, &init, 0);
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bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);
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val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
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if (val)
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bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME);
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/* update the same key to free the timer */
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bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);
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/* init more timers to check that htab operations
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* don't leak timer memory.
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*/
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key = 0;
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bpf_map_update_elem(&hmap, &key, &init, 0);
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val = bpf_map_lookup_elem(&hmap, &key);
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if (val)
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bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME);
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bpf_map_delete_elem(&hmap, &key);
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bpf_map_update_elem(&hmap, &key, &init, 0);
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val = bpf_map_lookup_elem(&hmap, &key);
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if (val)
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bpf_timer_init(&val->timer, &hmap, CLOCK_BOOTTIME);
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/* and with non-prealloc htab */
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key_malloc = 0;
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bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);
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val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
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if (val)
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bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME);
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bpf_map_delete_elem(&hmap_malloc, &key_malloc);
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bpf_map_update_elem(&hmap_malloc, &key_malloc, &init, 0);
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val = bpf_map_lookup_elem(&hmap_malloc, &key_malloc);
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if (val)
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bpf_timer_init(&val->timer, &hmap_malloc, CLOCK_BOOTTIME);
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return bpf_timer_test();
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}
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