netdev - [PATCH bpf-next v2 01/16] bpf: Remove migrate

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250108010728.207536-2-houtao@huaweicloud.com>
Date: Wed,  8 Jan 2025 09:07:13 +0800
From: Hou Tao <houtao@...weicloud.com>
To: bpf@...r.kernel.org,
	netdev@...r.kernel.org
Cc: Martin KaFai Lau <martin.lau@...ux.dev>,
	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	Andrii Nakryiko <andrii@...nel.org>,
	Eduard Zingerman <eddyz87@...il.com>,
	Song Liu <song@...nel.org>,
	Hao Luo <haoluo@...gle.com>,
	Yonghong Song <yonghong.song@...ux.dev>,
	Daniel Borkmann <daniel@...earbox.net>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...ichev.me>,
	Jiri Olsa <jolsa@...nel.org>,
	John Fastabend <john.fastabend@...il.com>,
	houtao1@...wei.com,
	xukuohai@...wei.com
Subject: [PATCH bpf-next v2 01/16] bpf: Remove migrate_{disable|enable} from LPM trie

From: Hou Tao <houtao1@...wei.com>

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@...wei.com>
---
 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 f8bc1e0961823..e8a772e643242 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;
 }
-- 
2.29.2