diff mbox series

[net-next,2/4] ipv4: use rcu in ip_fib_check_default()

Message ID 20241004134720.579244-3-edumazet@google.com (mailing list archive)
State Accepted
Commit fc38b28365e5f1396209d2878a34065468765087
Delegated to: Netdev Maintainers
Headers show
Series ipv4: preliminary work for per-netns RTNL | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
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: 6 this patch: 6
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 5 of 5 maintainers
netdev/build_clang success Errors and warnings before: 6 this patch: 6
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: 5 this patch: 5
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 46 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

Commit Message

Eric Dumazet Oct. 4, 2024, 1:47 p.m. UTC 
fib_info_devhash[] is not resized in fib_info_hash_move().

fib_nh structs are already freed after an rcu grace period.

This will allow to remove fib_info_lock in the following patch.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/fib_semantics.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

Comments

Kuniyuki Iwashima Oct. 4, 2024, 10:39 p.m. UTC | #1 
Date: Fri,  4 Oct 2024 13:47:18 +0000
From: Eric Dumazet <edumazet@google.com>
> fib_info_devhash[] is not resized in fib_info_hash_move().
> 
> fib_nh structs are already freed after an rcu grace period.
> 
> This will allow to remove fib_info_lock in the following patch.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
diff mbox series

Patch

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 1219d1b325910322dd978f3962a4cafa8e8db10b..e0ffb4ffd95d0f9ebc796c3129bc2f494fb478dd 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -275,7 +275,7 @@  void fib_release_info(struct fib_info *fi)
 			change_nexthops(fi) {
 				if (!nexthop_nh->fib_nh_dev)
 					continue;
-				hlist_del(&nexthop_nh->nh_hash);
+				hlist_del_rcu(&nexthop_nh->nh_hash);
 			} endfor_nexthops(fi)
 		}
 		/* Paired with READ_ONCE() from fib_table_lookup() */
@@ -431,28 +431,23 @@  static struct fib_info *fib_find_info(struct fib_info *nfi)
 }
 
 /* Check, that the gateway is already configured.
- * Used only by redirect accept routine.
+ * Used only by redirect accept routine, under rcu_read_lock();
  */
 int ip_fib_check_default(__be32 gw, struct net_device *dev)
 {
 	struct hlist_head *head;
 	struct fib_nh *nh;
 
-	spin_lock(&fib_info_lock);
-
 	head = fib_info_devhash_bucket(dev);
 
-	hlist_for_each_entry(nh, head, nh_hash) {
+	hlist_for_each_entry_rcu(nh, head, nh_hash) {
 		if (nh->fib_nh_dev == dev &&
 		    nh->fib_nh_gw4 == gw &&
 		    !(nh->fib_nh_flags & RTNH_F_DEAD)) {
-			spin_unlock(&fib_info_lock);
 			return 0;
 		}
 	}
 
-	spin_unlock(&fib_info_lock);
-
 	return -1;
 }
 
@@ -1606,7 +1601,7 @@  struct fib_info *fib_create_info(struct fib_config *cfg,
 			if (!nexthop_nh->fib_nh_dev)
 				continue;
 			head = fib_info_devhash_bucket(nexthop_nh->fib_nh_dev);
-			hlist_add_head(&nexthop_nh->nh_hash, head);
+			hlist_add_head_rcu(&nexthop_nh->nh_hash, head);
 		} endfor_nexthops(fi)
 	}
 	spin_unlock_bh(&fib_info_lock);