bpf: Consolidate spin_lock, timer management into btf_record

Now that kptr_off_tab has been refactored into btf_record, and can hold
more than one specific field type, accomodate bpf_spin_lock and
bpf_timer as well.

While they don't require any more metadata than offset, having all
special fields in one place allows us to share the same code for
allocated user defined types and handle both map values and these
allocated objects in a similar fashion.

As an optimization, we still keep spin_lock_off and timer_off offsets in
the btf_record structure, just to avoid having to find the btf_field
struct each time their offset is needed. This is mostly needed to
manipulate such objects in a map value at runtime. It's ok to hardcode
just one offset as more than one field is disallowed.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221103191013.1236066-8-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 8 insertions, 16 deletions

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index c5ea8f9bb7a9..50d254cd0709 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -222,7 +222,7 @@ static void htab_free_prealloced_timers(struct bpf_htab *htab)
 	u32 num_entries = htab->map.max_entries;
 	int i;
 
-	if (!map_value_has_timer(&htab->map))
+	if (!btf_record_has_field(htab->map.record, BPF_TIMER))
 		return;
 	if (htab_has_extra_elems(htab))
 		num_entries += num_possible_cpus();
@@ -231,9 +231,7 @@ static void htab_free_prealloced_timers(struct bpf_htab *htab)
 		struct htab_elem *elem;
 
 		elem = get_htab_elem(htab, i);
-		bpf_timer_cancel_and_free(elem->key +
-					  round_up(htab->map.key_size, 8) +
-					  htab->map.timer_off);
+		bpf_obj_free_timer(htab->map.record, elem->key + round_up(htab->map.key_size, 8));
 		cond_resched();
 	}
 }
@@ -763,8 +761,6 @@ static void check_and_free_fields(struct bpf_htab *htab,
 {
 	void *map_value = elem->key + round_up(htab->map.key_size, 8);
 
-	if (map_value_has_timer(&htab->map))
-		bpf_timer_cancel_and_free(map_value + htab->map.timer_off);
 	bpf_obj_free_fields(htab->map.record, map_value);
 }
 
@@ -1089,7 +1085,7 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
 	head = &b->head;
 
 	if (unlikely(map_flags & BPF_F_LOCK)) {
-		if (unlikely(!map_value_has_spin_lock(map)))
+		if (unlikely(!btf_record_has_field(map->record, BPF_SPIN_LOCK)))
 			return -EINVAL;
 		/* find an element without taking the bucket lock */
 		l_old = lookup_nulls_elem_raw(head, hash, key, key_size,
@@ -1472,12 +1468,8 @@ static void htab_free_malloced_timers(struct bpf_htab *htab)
 		struct htab_elem *l;
 
 		hlist_nulls_for_each_entry(l, n, head, hash_node) {
-			/* We don't reset or free kptr on uref dropping to zero,
-			 * hence just free timer.
-			 */
-			bpf_timer_cancel_and_free(l->key +
-						  round_up(htab->map.key_size, 8) +
-						  htab->map.timer_off);
+			/* 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));
 		}
 		cond_resched_rcu();
 	}
@@ -1488,8 +1480,8 @@ static void htab_map_free_timers(struct bpf_map *map)
 {
 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 
-	/* We don't reset or free kptr on uref dropping to zero. */
-	if (!map_value_has_timer(&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);
@@ -1673,7 +1665,7 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map,
 
 	elem_map_flags = attr->batch.elem_flags;
 	if ((elem_map_flags & ~BPF_F_LOCK) ||
-	    ((elem_map_flags & BPF_F_LOCK) && !map_value_has_spin_lock(map)))
+	    ((elem_map_flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_LOCK)))
 		return -EINVAL;
 
 	map_flags = attr->batch.flags;