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bpf: Remove migrate_{disable|enable} from LPM trie

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Both bpf program and bpf syscall may invoke ->update or ->delete
operation for LPM trie. For bpf program, its running context has already
disabled migration explicitly through (migrate_disable()) or implicitly
through (preempt_disable() or disable irq). For bpf syscall, the
migration is disabled through the use of bpf_disable_instrumentation()
before invoking the corresponding map operation callback.

Therefore, it is safe to remove the migrate_{disable|enable){} pair from
LPM trie.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Hou Tao 2025-01-08 09:07:13 +08:00 committed by Alexei Starovoitov
parent bfaac2a0b9
commit 1b1a01db17
1 changed files with 4 additions and 16 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

20
kernel/bpf/lpm_trie.c
View file

@ -289,16 +289,11 @@ static void *trie_lookup_elem(struct bpf_map *map, void *_key)
}
static struct lpm_trie_node *lpm_trie_node_alloc(struct lpm_trie *trie,
const void *value,
bool disable_migration)
const void *value)
{
struct lpm_trie_node *node;
if (disable_migration)
migrate_disable();
node = bpf_mem_cache_alloc(&trie->ma);
if (disable_migration)
migrate_enable();
if (!node)
return NULL;
@ -342,10 +337,8 @@ static long trie_update_elem(struct bpf_map *map,
if (key->prefixlen > trie->max_prefixlen)
return -EINVAL;
/* Allocate and fill a new node. Need to disable migration before
* invoking bpf_mem_cache_alloc().
*/
new_node = lpm_trie_node_alloc(trie, value, true);
/* Allocate and fill a new node */
new_node = lpm_trie_node_alloc(trie, value);
if (!new_node)
return -ENOMEM;
@ -425,8 +418,7 @@ static long trie_update_elem(struct bpf_map *map,
goto out;
}
/* migration is disabled within the locked scope */
im_node = lpm_trie_node_alloc(trie, NULL, false);
im_node = lpm_trie_node_alloc(trie, NULL);
if (!im_node) {
trie->n_entries--;
ret = -ENOMEM;
@ -452,11 +444,9 @@ static long trie_update_elem(struct bpf_map *map,
out:
raw_spin_unlock_irqrestore(&trie->lock, irq_flags);
migrate_disable();
if (ret)
bpf_mem_cache_free(&trie->ma, new_node);
bpf_mem_cache_free_rcu(&trie->ma, free_node);
migrate_enable();
return ret;
}
@ -555,10 +545,8 @@ static long trie_delete_elem(struct bpf_map *map, void *_key)
out:
raw_spin_unlock_irqrestore(&trie->lock, irq_flags);
migrate_disable();
bpf_mem_cache_free_rcu(&trie->ma, free_parent);
bpf_mem_cache_free_rcu(&trie->ma, free_node);
migrate_enable();
return ret;
}