diff mbox series

[v2,net-next,7/7] neighbour: Convert RTM_SETNEIGHTBL to RCU.

Message ID 20250418012727.57033-8-kuniyu@amazon.com (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series neighbour: Convert RTM_GETNEIGH and RTM_{GET,SET}NEIGHTBL to RCU. | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 1 maintainers not CCed: gnaaman@drivenets.com
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 2 this patch: 2
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 40 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2025-04-18--12-00 (tests: 916)

Commit Message

Kuniyuki Iwashima April 18, 2025, 1:26 a.m. UTC 
neightbl_set() fetches neigh_tables[] and updates attributes under
write_lock_bh(&tbl->lock), so RTNL is not needed.

Let's fetch the table under RCU and drop RTNL for RTM_SETNEIGHTBL.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/core/neighbour.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 38732d8f0ed7..09894e559244 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2281,8 +2281,10 @@  static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh,
 
 	ndtmsg = nlmsg_data(nlh);
 
+	rcu_read_lock();
+
 	for (tidx = 0; tidx < NEIGH_NR_TABLES; tidx++) {
-		tbl = rcu_dereference_rtnl(neigh_tables[tidx]);
+		tbl = rcu_dereference(neigh_tables[tidx]);
 		if (!tbl)
 			continue;
 		if (ndtmsg->ndtm_family && tbl->family != ndtmsg->ndtm_family)
@@ -2293,8 +2295,10 @@  static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh,
 		}
 	}
 
-	if (!found)
-		return -ENOENT;
+	if (!found) {
+		err = -ENOENT;
+		goto errout_rcu;
+	}
 
 	/*
 	 * We acquire tbl->lock to be nice to the periodic timers and
@@ -2421,6 +2425,8 @@  static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh,
 
 errout_tbl_lock:
 	write_unlock_bh(&tbl->lock);
+errout_rcu:
+	rcu_read_unlock();
 errout:
 	return err;
 }
@@ -3817,7 +3823,8 @@  static const struct rtnl_msg_handler neigh_rtnl_msg_handlers[] __initconst = {
 	 .flags = RTNL_FLAG_DOIT_UNLOCKED | RTNL_FLAG_DUMP_UNLOCKED},
 	{.msgtype = RTM_GETNEIGHTBL, .dumpit = neightbl_dump_info,
 	 .flags = RTNL_FLAG_DUMP_UNLOCKED},
-	{.msgtype = RTM_SETNEIGHTBL, .doit = neightbl_set},
+	{.msgtype = RTM_SETNEIGHTBL, .doit = neightbl_set,
+	 .flags = RTNL_FLAG_DOIT_UNLOCKED},
 };
 
 static int __init neigh_init(void)