diff mbox series

[net-next,3/5] ipv6: use READ_ONCE()/WRITE_ONCE() on fib6_table->fib_seq

Message ID 20241009184405.3752829-4-edumazet@google.com (mailing list archive)
State Accepted
Commit e60ea45447768c48309b944596a8a34f6bae50e2
Delegated to: Netdev Maintainers
Headers show
Series net: remove RTNL from fib_seq_sum() | 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: 6 this patch: 6
netdev/build_tools success Errors and warnings before: 0 (+1) this patch: 0 (+1)
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: 502 this patch: 502
netdev/checkpatch warning CHECK: Please use a blank line after function/struct/union/enum declarations
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-2024-10-11--15-00 (tests: 776)

Commit Message

Eric Dumazet Oct. 9, 2024, 6:44 p.m. UTC 
Using RTNL to protect ops->fib_rules_seq reads seems a big hammer.

Writes are protected by RTNL.
We can use READ_ONCE() when reading it.

Constify 'struct net' argument of fib6_tables_seq_read() and
fib6_rules_seq_read().

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/net/ip6_fib.h |  8 ++++----
 net/ipv6/fib6_rules.c |  2 +-
 net/ipv6/ip6_fib.c    | 14 +++++++-------
 3 files changed, 12 insertions(+), 12 deletions(-)

Comments

Kuniyuki Iwashima Oct. 9, 2024, 11:55 p.m. UTC | #1 
From: Eric Dumazet <edumazet@google.com>
Date: Wed,  9 Oct 2024 18:44:03 +0000
> Using RTNL to protect ops->fib_rules_seq reads seems a big hammer.
> 
> Writes are protected by RTNL.
> We can use READ_ONCE() when reading it.
> 
> Constify 'struct net' argument of fib6_tables_seq_read() and
> fib6_rules_seq_read().
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

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

Patch

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 6cb867ce4878423fbb9049e69445a6dbf8f31ba7..7c87873ae211c5fa80d34e8f3b8df0e813976390 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -394,7 +394,7 @@  struct fib6_table {
 	struct fib6_node	tb6_root;
 	struct inet_peer_base	tb6_peers;
 	unsigned int		flags;
-	unsigned int		fib_seq;
+	unsigned int		fib_seq; /* writes protected by rtnl_mutex */
 	struct hlist_head       tb6_gc_hlist;	/* GC candidates */
 #define RT6_TABLE_HAS_DFLT_ROUTER	BIT(0)
 };
@@ -563,7 +563,7 @@  int call_fib6_notifiers(struct net *net, enum fib_event_type event_type,
 int __net_init fib6_notifier_init(struct net *net);
 void __net_exit fib6_notifier_exit(struct net *net);
 
-unsigned int fib6_tables_seq_read(struct net *net);
+unsigned int fib6_tables_seq_read(const struct net *net);
 int fib6_tables_dump(struct net *net, struct notifier_block *nb,
 		     struct netlink_ext_ack *extack);
 
@@ -632,7 +632,7 @@  void fib6_rules_cleanup(void);
 bool fib6_rule_default(const struct fib_rule *rule);
 int fib6_rules_dump(struct net *net, struct notifier_block *nb,
 		    struct netlink_ext_ack *extack);
-unsigned int fib6_rules_seq_read(struct net *net);
+unsigned int fib6_rules_seq_read(const struct net *net);
 
 static inline bool fib6_rules_early_flow_dissect(struct net *net,
 						 struct sk_buff *skb,
@@ -676,7 +676,7 @@  static inline int fib6_rules_dump(struct net *net, struct notifier_block *nb,
 {
 	return 0;
 }
-static inline unsigned int fib6_rules_seq_read(struct net *net)
+static inline unsigned int fib6_rules_seq_read(const struct net *net)
 {
 	return 0;
 }
diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
index 04a9ed5e8310f23cb7d947b732be5dd19916bf39..c85c1627cb16ed0bdfe4c6026bb0132cdd7be6b7 100644
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -56,7 +56,7 @@  int fib6_rules_dump(struct net *net, struct notifier_block *nb,
 	return fib_rules_dump(net, nb, AF_INET6, extack);
 }
 
-unsigned int fib6_rules_seq_read(struct net *net)
+unsigned int fib6_rules_seq_read(const struct net *net)
 {
 	return fib_rules_seq_read(net, AF_INET6);
 }
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index eb111d20615c6274647eeb413d0b9475aaa3ae6c..cea160b249d2d75d03c867d2298da76eb0c7114e 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -345,17 +345,17 @@  static void __net_init fib6_tables_init(struct net *net)
 
 #endif
 
-unsigned int fib6_tables_seq_read(struct net *net)
+unsigned int fib6_tables_seq_read(const struct net *net)
 {
 	unsigned int h, fib_seq = 0;
 
 	rcu_read_lock();
 	for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
-		struct hlist_head *head = &net->ipv6.fib_table_hash[h];
-		struct fib6_table *tb;
+		const struct hlist_head *head = &net->ipv6.fib_table_hash[h];
+		const struct fib6_table *tb;
 
 		hlist_for_each_entry_rcu(tb, head, tb6_hlist)
-			fib_seq += tb->fib_seq;
+			fib_seq += READ_ONCE(tb->fib_seq);
 	}
 	rcu_read_unlock();
 
@@ -400,7 +400,7 @@  int call_fib6_entry_notifiers(struct net *net,
 		.rt = rt,
 	};
 
-	rt->fib6_table->fib_seq++;
+	WRITE_ONCE(rt->fib6_table->fib_seq, rt->fib6_table->fib_seq + 1);
 	return call_fib6_notifiers(net, event_type, &info.info);
 }
 
@@ -416,7 +416,7 @@  int call_fib6_multipath_entry_notifiers(struct net *net,
 		.nsiblings = nsiblings,
 	};
 
-	rt->fib6_table->fib_seq++;
+	WRITE_ONCE(rt->fib6_table->fib_seq, rt->fib6_table->fib_seq + 1);
 	return call_fib6_notifiers(net, event_type, &info.info);
 }
 
@@ -427,7 +427,7 @@  int call_fib6_entry_notifiers_replace(struct net *net, struct fib6_info *rt)
 		.nsiblings = rt->fib6_nsiblings,
 	};
 
-	rt->fib6_table->fib_seq++;
+	WRITE_ONCE(rt->fib6_table->fib_seq, rt->fib6_table->fib_seq + 1);
 	return call_fib6_notifiers(net, FIB_EVENT_ENTRY_REPLACE, &info.info);
 }