From: Hou Tao <houtao1@xxxxxxxxxx>
When destroying sock storage, it invokes bpf_local_storage_destroy() to
remove all storage elements saved in the sock storage. The destroy
procedure will call bpf_selem_free() to free the element, and
bpf_selem_free() calls bpf_obj_free_fields() to free the special fields
in map value (e.g., kptr). Since kptrs may be allocated from bpf memory
allocator, migrate_{disable|enable} pairs are necessary for the freeing
of these kptrs.
To simplify reasoning about when migrate_disable() is needed for the
freeing of these dynamically-allocated kptrs, let the caller to
guarantee migration is disabled before invoking bpf_obj_free_fields().
Therefore, the patch adds migrate_{disable|enable} pair in
bpf_sock_storage_free(). 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>
---
net/core/bpf_sk_storage.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
index 2f4ed83a75ae6..aa536ecd5d390 100644
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -50,15 +50,16 @@ void bpf_sk_storage_free(struct sock *sk)
{
struct bpf_local_storage *sk_storage;
+ migrate_disable();
rcu_read_lock();
sk_storage = rcu_dereference(sk->sk_bpf_storage);
- if (!sk_storage) {
- rcu_read_unlock();
- return;
- }
+ if (!sk_storage)
+ goto out;
bpf_local_storage_destroy(sk_storage);
+out:
rcu_read_unlock();
+ migrate_enable();
}
static void bpf_sk_storage_map_free(struct bpf_map *map)
--
2.29.2
