bpf: Remove migrate_{disable|enable} in htab_elem_free

htab_elem_free() has two call-sites: delete_all_elements() has already
disabled migration, free_htab_elem() is invoked by other 4 functions:
__htab_map_lookup_and_delete_elem, __htab_map_lookup_and_delete_batch,
htab_map_update_elem and htab_map_delete_elem.

BPF syscall has already disabled migration before invoking
->map_update_elem, ->map_delete_elem, and ->map_lookup_and_delete_elem
callbacks for hash map. __htab_map_lookup_and_delete_batch() also
disables migration before invoking free_htab_elem(). ->map_update_elem()
and ->map_delete_elem() of hash map may be invoked by BPF program and
the running context of BPF program has already disabled migration.
Therefore, it is safe to remove the migration_{disable|enable} pair in
htab_elem_free()

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 42af7fac61b9c612fc7654e81c45abba225f7b05..bccae537f9d222c73eeecffc1e8efabe63b38d3b 100644 (file)
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -897,11 +897,9 @@ static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
 {
        check_and_free_fields(htab, l);
 
-       migrate_disable();
        if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
                bpf_mem_cache_free(&htab->pcpu_ma, l->ptr_to_pptr);
        bpf_mem_cache_free(&htab->ma, l);
-       migrate_enable();
 }
 
 static void htab_put_fd_value(struct bpf_htab *htab, struct htab_elem *l)