From: Hou Tao <houtao1@xxxxxxxxxx>
bpf_local_storage_map_free() invokes bpf_selem_unlink() to unlink and
free the element from the storage map. It may invoke
bpf_obj_free_fields() to free the special fields in the map value. Since
these special fields may be allocated from bpf memory allocator,
migrate_{disable|enable} pairs are necessary for the freeing of these
objects.
To simplify reasoning about when migrate_disable() is needed for the
freeing of these dynamically-allocated objects, let the caller to
guarantee migration is disabled before invoking bpf_obj_free_fields().
Therefore, the patch moves migrate_{disable|enable} out of the
busy_counter condition and calls migrate_disable() before invoking
bpf_obj_free_fields(). The migrate_{disable|enable} pairs in the
underlying implementation of bpf_obj_free_fields() will be removed by
the following patch.
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
kernel/bpf/bpf_local_storage.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c
index 615a3034baeb..b649cf736438 100644
--- a/kernel/bpf/bpf_local_storage.c
+++ b/kernel/bpf/bpf_local_storage.c
@@ -905,15 +905,13 @@ void bpf_local_storage_map_free(struct bpf_map *map,
while ((selem = hlist_entry_safe(
rcu_dereference_raw(hlist_first_rcu(&b->list)),
struct bpf_local_storage_elem, map_node))) {
- if (busy_counter) {
- migrate_disable();
+ migrate_disable();
+ if (busy_counter)
this_cpu_inc(*busy_counter);
- }
bpf_selem_unlink(selem, true);
- if (busy_counter) {
+ if (busy_counter)
this_cpu_dec(*busy_counter);
- migrate_enable();
- }
+ migrate_enable();
cond_resched_rcu();
}
rcu_read_unlock();
--
2.29.2
