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bpf: allow struct bpf_wq to be embedded in arraymaps and hashmaps

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Currently bpf_wq_cancel_and_free() is just a placeholder as there is
no memory allocation for bpf_wq just yet.

Again, duplication of the bpf_timer approach

Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Link: https://lore.kernel.org/r/20240420-bpf_wq-v2-9-6c986a5a741f@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Benjamin Tissoires 2024-04-20 11:09:09 +02:00 committed by Alexei Starovoitov
parent d940c9b94d
commit 246331e3f1
5 changed files with 73 additions and 19 deletions
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2
include/linux/bpf.h
View file

@ -534,6 +534,7 @@ static inline void zero_map_value(struct bpf_map *map, void *dst)
void copy_map_value_locked(struct bpf_map *map, void *dst, void *src,
bool lock_src);
void bpf_timer_cancel_and_free(void *timer);
void bpf_wq_cancel_and_free(void *timer);
void bpf_list_head_free(const struct btf_field *field, void *list_head,
struct bpf_spin_lock *spin_lock);
void bpf_rb_root_free(const struct btf_field *field, void *rb_root,
@ -2204,6 +2205,7 @@ void bpf_map_free_record(struct bpf_map *map);
struct btf_record *btf_record_dup(const struct btf_record *rec);
bool btf_record_equal(const struct btf_record *rec_a, const struct btf_record *rec_b);
void bpf_obj_free_timer(const struct btf_record *rec, void *obj);
void bpf_obj_free_workqueue(const struct btf_record *rec, void *obj);
void bpf_obj_free_fields(const struct btf_record *rec, void *obj);
void __bpf_obj_drop_impl(void *p, const struct btf_record *rec, bool percpu);

18
kernel/bpf/arraymap.c
View file

@ -428,17 +428,21 @@ static void *array_map_vmalloc_addr(struct bpf_array *array)
return (void *)round_down((unsigned long)array, PAGE_SIZE);
}
static void array_map_free_timers(struct bpf_map *map)
static void array_map_free_timers_wq(struct bpf_map *map)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
int i;
/* We don't reset or free fields other than timer on uref dropping to zero. */
if (!btf_record_has_field(map->record, BPF_TIMER))
return;
/* We don't reset or free fields other than timer and workqueue
* on uref dropping to zero.
*/
if (btf_record_has_field(map->record, BPF_TIMER))
for (i = 0; i < array->map.max_entries; i++)
bpf_obj_free_timer(map->record, array_map_elem_ptr(array, i));
for (i = 0; i < array->map.max_entries; i++)
bpf_obj_free_timer(map->record, array_map_elem_ptr(array, i));
if (btf_record_has_field(map->record, BPF_WORKQUEUE))
for (i = 0; i < array->map.max_entries; i++)
bpf_obj_free_workqueue(map->record, array_map_elem_ptr(array, i));
}
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
@ -782,7 +786,7 @@ const struct bpf_map_ops array_map_ops = {
.map_alloc = array_map_alloc,
.map_free = array_map_free,
.map_get_next_key = array_map_get_next_key,
.map_release_uref = array_map_free_timers,
.map_release_uref = array_map_free_timers_wq,
.map_lookup_elem = array_map_lookup_elem,
.map_update_elem = array_map_update_elem,
.map_delete_elem = array_map_delete_elem,

55
kernel/bpf/hashtab.c
View file

@ -240,6 +240,26 @@ static void htab_free_prealloced_timers(struct bpf_htab *htab)
}
}
static void htab_free_prealloced_wq(struct bpf_htab *htab)
{
u32 num_entries = htab->map.max_entries;
int i;
if (!btf_record_has_field(htab->map.record, BPF_WORKQUEUE))
return;
if (htab_has_extra_elems(htab))
num_entries += num_possible_cpus();
for (i = 0; i < num_entries; i++) {
struct htab_elem *elem;
elem = get_htab_elem(htab, i);
bpf_obj_free_workqueue(htab->map.record,
elem->key + round_up(htab->map.key_size, 8));
cond_resched();
}
}
static void htab_free_prealloced_fields(struct bpf_htab *htab)
{
u32 num_entries = htab->map.max_entries;
@ -1495,7 +1515,7 @@ static void delete_all_elements(struct bpf_htab *htab)
migrate_enable();
}
static void htab_free_malloced_timers(struct bpf_htab *htab)
static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer)
{
int i;
@ -1507,24 +1527,35 @@ static void htab_free_malloced_timers(struct bpf_htab *htab)
hlist_nulls_for_each_entry(l, n, head, hash_node) {
/* We only free timer on uref dropping to zero */
bpf_obj_free_timer(htab->map.record, l->key + round_up(htab->map.key_size, 8));
if (is_timer)
bpf_obj_free_timer(htab->map.record,
l->key + round_up(htab->map.key_size, 8));
else
bpf_obj_free_workqueue(htab->map.record,
l->key + round_up(htab->map.key_size, 8));
}
cond_resched_rcu();
}
rcu_read_unlock();
}
static void htab_map_free_timers(struct bpf_map *map)
static void htab_map_free_timers_and_wq(struct bpf_map *map)
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
/* We only free timer on uref dropping to zero */
if (!btf_record_has_field(htab->map.record, BPF_TIMER))
return;
if (!htab_is_prealloc(htab))
htab_free_malloced_timers(htab);
else
htab_free_prealloced_timers(htab);
/* We only free timer and workqueue on uref dropping to zero */
if (btf_record_has_field(htab->map.record, BPF_TIMER)) {
if (!htab_is_prealloc(htab))
htab_free_malloced_timers_or_wq(htab, true);
else
htab_free_prealloced_timers(htab);
}
if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE)) {
if (!htab_is_prealloc(htab))
htab_free_malloced_timers_or_wq(htab, false);
else
htab_free_prealloced_wq(htab);
}
}
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
@ -2260,7 +2291,7 @@ const struct bpf_map_ops htab_map_ops = {
.map_alloc = htab_map_alloc,
.map_free = htab_map_free,
.map_get_next_key = htab_map_get_next_key,
.map_release_uref = htab_map_free_timers,
.map_release_uref = htab_map_free_timers_and_wq,
.map_lookup_elem = htab_map_lookup_elem,
.map_lookup_and_delete_elem = htab_map_lookup_and_delete_elem,
.map_update_elem = htab_map_update_elem,
@ -2281,7 +2312,7 @@ const struct bpf_map_ops htab_lru_map_ops = {
.map_alloc = htab_map_alloc,
.map_free = htab_map_free,
.map_get_next_key = htab_map_get_next_key,
.map_release_uref = htab_map_free_timers,
.map_release_uref = htab_map_free_timers_and_wq,
.map_lookup_elem = htab_lru_map_lookup_elem,
.map_lookup_and_delete_elem = htab_lru_map_lookup_and_delete_elem,
.map_lookup_elem_sys_only = htab_lru_map_lookup_elem_sys,

8
kernel/bpf/helpers.c
View file

@ -1468,6 +1468,14 @@ void bpf_timer_cancel_and_free(void *val)
kfree_rcu(t, cb.rcu);
}
/* This function is called by map_delete/update_elem for individual element and
* by ops->map_release_uref when the user space reference to a map reaches zero.
*/
void bpf_wq_cancel_and_free(void *val)
{
BTF_TYPE_EMIT(struct bpf_wq);
}
BPF_CALL_2(bpf_kptr_xchg, void *, map_value, void *, ptr)
{
unsigned long *kptr = map_value;

9
kernel/bpf/syscall.c
View file

@ -661,6 +661,13 @@ void bpf_obj_free_timer(const struct btf_record *rec, void *obj)
bpf_timer_cancel_and_free(obj + rec->timer_off);
}
void bpf_obj_free_workqueue(const struct btf_record *rec, void *obj)
{
if (WARN_ON_ONCE(!btf_record_has_field(rec, BPF_WORKQUEUE)))
return;
bpf_wq_cancel_and_free(obj + rec->wq_off);
}
void bpf_obj_free_fields(const struct btf_record *rec, void *obj)
{
const struct btf_field *fields;
@ -682,6 +689,7 @@ void bpf_obj_free_fields(const struct btf_record *rec, void *obj)
bpf_timer_cancel_and_free(field_ptr);
break;
case BPF_WORKQUEUE:
bpf_wq_cancel_and_free(field_ptr);
break;
case BPF_KPTR_UNREF:
WRITE_ONCE(*(u64 *)field_ptr, 0);
@ -1119,6 +1127,7 @@ static int map_check_btf(struct bpf_map *map, struct bpf_token *token,
}
break;
case BPF_TIMER:
case BPF_WORKQUEUE:
if (map->map_type != BPF_MAP_TYPE_HASH &&
map->map_type != BPF_MAP_TYPE_LRU_HASH &&
map->map_type != BPF_MAP_TYPE_ARRAY) {