Re: [PATCH v5 bpf-next 04/11] bpf: Add map side support for bpf timers.
From: Martin KaFai Lau <hidden>
Date: 2021-07-09 01:51:43
Also in:
bpf
On Wed, Jul 07, 2021 at 06:18:26PM -0700, Alexei Starovoitov wrote: [ ... ]
quoted hunk ↗ jump to hunk
+static void array_map_free_timers(struct bpf_map *map) +{ + struct bpf_array *array = container_of(map, struct bpf_array, map); + int i; + + if (likely(!map_value_has_timer(map))) + return; + + for (i = 0; i < array->map.max_entries; i++) + bpf_timer_cancel_and_free(array->value + array->elem_size * i + + map->timer_off); +} + /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ static void array_map_free(struct bpf_map *map) {@@ -382,6 +402,7 @@ static void array_map_free(struct bpf_map *map) if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY) bpf_array_free_percpu(array); + array_map_free_timers(map);
array_map_free() is called when map->refcnt reached 0. By then, map->usercnt should have reached 0 before and array_map_free_timers() should have already been called, so no need to call it here again? The same goes for hashtab. [ ... ]
quoted hunk ↗ jump to hunk
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index cb4b72997d9b..7780131f710e 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c@@ -3046,43 +3046,92 @@ static void btf_struct_log(struct btf_verifier_env *env, btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t)); } -/* find 'struct bpf_spin_lock' in map value. - * return >= 0 offset if found - * and < 0 in case of error - */ -int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t) +static int btf_find_struct_field(const struct btf *btf, const struct btf_type *t, + const char *name, int sz, int align) { const struct btf_member *member; u32 i, off = -ENOENT; - if (!__btf_type_is_struct(t)) - return -EINVAL; - for_each_member(i, t, member) { const struct btf_type *member_type = btf_type_by_id(btf, member->type); if (!__btf_type_is_struct(member_type)) continue; - if (member_type->size != sizeof(struct bpf_spin_lock)) + if (member_type->size != sz) continue; - if (strcmp(__btf_name_by_offset(btf, member_type->name_off), - "bpf_spin_lock")) + if (strcmp(__btf_name_by_offset(btf, member_type->name_off), name)) continue; if (off != -ENOENT) - /* only one 'struct bpf_spin_lock' is allowed */ + /* only one such field is allowed */ return -E2BIG; off = btf_member_bit_offset(t, member); if (off % 8) /* valid C code cannot generate such BTF */ return -EINVAL; off /= 8; - if (off % __alignof__(struct bpf_spin_lock)) - /* valid struct bpf_spin_lock will be 4 byte aligned */ + if (off % align) + return -EINVAL; + } + return off; +} + +static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t, + const char *name, int sz, int align) +{ + const struct btf_var_secinfo *vsi; + u32 i, off = -ENOENT; + + for_each_vsi(i, t, vsi) { + const struct btf_type *var = btf_type_by_id(btf, vsi->type); + const struct btf_type *var_type = btf_type_by_id(btf, var->type); + + if (!__btf_type_is_struct(var_type)) + continue; + if (var_type->size != sz) + continue; + if (vsi->size != sz) + continue; + if (strcmp(__btf_name_by_offset(btf, var_type->name_off), name)) + continue; + if (off != -ENOENT) + /* only one such field is allowed */ + return -E2BIG; + off = vsi->offset; + if (off % align) return -EINVAL; } return off; } +static int btf_find_field(const struct btf *btf, const struct btf_type *t, + const char *name, int sz, int align) +{ + + if (__btf_type_is_struct(t)) + return btf_find_struct_field(btf, t, name, sz, align); + else if (btf_type_is_datasec(t)) + return btf_find_datasec_var(btf, t, name, sz, align);
iiuc, a global struct bpf_timer is not supported. I am not sure why it needs to find the timer in datasec here. or it meant to error out and potentially give a verifier log? I don't see where is the verifier reporting error though.
+static void htab_free_malloced_timers(struct bpf_htab *htab)
+{
+ int i;
+
+ rcu_read_lock();
+ for (i = 0; i < htab->n_buckets; i++) {
+ struct hlist_nulls_head *head = select_bucket(htab, i);
+ struct hlist_nulls_node *n;
+ struct htab_elem *l;
+
+ hlist_nulls_for_each_entry(l, n, head, hash_node)need the _rcu() variant here. May be put rcu_read_lock/unlock() in the loop and do a cond_resched() in case the hashtab is large.