From 1b1a01db17af7a44cae8d8d7d7a18dbb056be40f Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Wed, 8 Jan 2025 09:07:13 +0800 Subject: [PATCH] bpf: Remove migrate_{disable|enable} from LPM trie 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 Link: https://lore.kernel.org/r/20250108010728.207536-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/lpm_trie.c | 20 ++++---------------- 1 file changed, 4 insertions(+), 16 deletions(-) diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index f8bc1e096182..e8a772e64324 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -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; }