diff mbox series

[v2,net-next] ipv6: remove RTNL protection from ip6addrlbl_dump()

Message ID 20240404132413.2633866-1-edumazet@google.com (mailing list archive)
State Accepted
Commit eec53cc38c4aba41bc3fabd0a75bc30c2c8ea332
Delegated to: Netdev Maintainers
Headers show
Series [v2,net-next] ipv6: remove RTNL protection from ip6addrlbl_dump() | expand

Checks

Context Check Description
netdev/series_format success Single patches do not need cover letters
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: 943 this patch: 943
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: 954 this patch: 954
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: 954 this patch: 954
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 62 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-2024-04-07--00-00 (tests: 956)

Commit Message

Eric Dumazet April 4, 2024, 1:24 p.m. UTC 
No longer hold RTNL while calling ip6addrlbl_dump()
("ip addrlabel show")

ip6addrlbl_dump() was already mostly relying on RCU anyway.

Add READ_ONCE()/WRITE_ONCE() annotations around
net->ipv6.ip6addrlbl_table.seq

Note that ifal_seq value is currently ignored in iproute2,
and a bit weak.

We might user later cb->seq  / nl_dump_check_consistent()
protocol if needed.

Also change return value for a completed dump,
so that NLMSG_DONE can be appended to current skb,
saving one recvmsg() system call.

v2: read net->ipv6.ip6addrlbl_table.seq once, (David Ahern)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link:https://lore.kernel.org/netdev/67f5cb70-14a4-4455-8372-f039da2f15c2@kernel.org/
---
 net/ipv6/addrlabel.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

Comments

David Ahern April 4, 2024, 6:06 p.m. UTC | #1 
On 4/4/24 7:24 AM, Eric Dumazet wrote:
> No longer hold RTNL while calling ip6addrlbl_dump()
> ("ip addrlabel show")
> 
> ip6addrlbl_dump() was already mostly relying on RCU anyway.
> 
> Add READ_ONCE()/WRITE_ONCE() annotations around
> net->ipv6.ip6addrlbl_table.seq
> 
> Note that ifal_seq value is currently ignored in iproute2,
> and a bit weak.
> 
> We might user later cb->seq  / nl_dump_check_consistent()
> protocol if needed.
> 
> Also change return value for a completed dump,
> so that NLMSG_DONE can be appended to current skb,
> saving one recvmsg() system call.
> 
> v2: read net->ipv6.ip6addrlbl_table.seq once, (David Ahern)
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Link:https://lore.kernel.org/netdev/67f5cb70-14a4-4455-8372-f039da2f15c2@kernel.org/
> ---
>  net/ipv6/addrlabel.c | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>
patchwork-bot+netdevbpf@kernel.org April 8, 2024, 10:10 a.m. UTC | #2 
Hello:

This patch was applied to netdev/net-next.git (main)
by David S. Miller <davem@davemloft.net>:

On Thu,  4 Apr 2024 13:24:13 +0000 you wrote:
> No longer hold RTNL while calling ip6addrlbl_dump()
> ("ip addrlabel show")
> 
> ip6addrlbl_dump() was already mostly relying on RCU anyway.
> 
> Add READ_ONCE()/WRITE_ONCE() annotations around
> net->ipv6.ip6addrlbl_table.seq
> 
> [...]

Here is the summary with links:
  - [v2,net-next] ipv6: remove RTNL protection from ip6addrlbl_dump()
    https://git.kernel.org/netdev/net-next/c/eec53cc38c4a

You are awesome, thank you!
diff mbox series

Patch

diff --git a/net/ipv6/addrlabel.c b/net/ipv6/addrlabel.c
index 17ac45aa7194ce9c148ed95e14dd575d17feeb98..acd70b5992a7b9c1aadcfb9a279da7fe6aebfed9 100644
--- a/net/ipv6/addrlabel.c
+++ b/net/ipv6/addrlabel.c
@@ -234,7 +234,8 @@  static int __ip6addrlbl_add(struct net *net, struct ip6addrlbl_entry *newp,
 		hlist_add_head_rcu(&newp->list, &net->ipv6.ip6addrlbl_table.head);
 out:
 	if (!ret)
-		net->ipv6.ip6addrlbl_table.seq++;
+		WRITE_ONCE(net->ipv6.ip6addrlbl_table.seq,
+			   net->ipv6.ip6addrlbl_table.seq + 1);
 	return ret;
 }
 
@@ -445,7 +446,7 @@  static void ip6addrlbl_putmsg(struct nlmsghdr *nlh,
 };
 
 static int ip6addrlbl_fill(struct sk_buff *skb,
-			   struct ip6addrlbl_entry *p,
+			   const struct ip6addrlbl_entry *p,
 			   u32 lseq,
 			   u32 portid, u32 seq, int event,
 			   unsigned int flags)
@@ -498,7 +499,8 @@  static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	struct net *net = sock_net(skb->sk);
 	struct ip6addrlbl_entry *p;
 	int idx = 0, s_idx = cb->args[0];
-	int err;
+	int err = 0;
+	u32 lseq;
 
 	if (cb->strict_check) {
 		err = ip6addrlbl_valid_dump_req(nlh, cb->extack);
@@ -507,10 +509,11 @@  static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	}
 
 	rcu_read_lock();
+	lseq = READ_ONCE(net->ipv6.ip6addrlbl_table.seq);
 	hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {
 		if (idx >= s_idx) {
 			err = ip6addrlbl_fill(skb, p,
-					      net->ipv6.ip6addrlbl_table.seq,
+					      lseq,
 					      NETLINK_CB(cb->skb).portid,
 					      nlh->nlmsg_seq,
 					      RTM_NEWADDRLABEL,
@@ -522,7 +525,7 @@  static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	}
 	rcu_read_unlock();
 	cb->args[0] = idx;
-	return skb->len;
+	return err;
 }
 
 static inline int ip6addrlbl_msgsize(void)
@@ -614,7 +617,7 @@  static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 
 	rcu_read_lock();
 	p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);
-	lseq = net->ipv6.ip6addrlbl_table.seq;
+	lseq = READ_ONCE(net->ipv6.ip6addrlbl_table.seq);
 	if (p)
 		err = ip6addrlbl_fill(skb, p, lseq,
 				      NETLINK_CB(in_skb).portid,
@@ -647,6 +650,7 @@  int __init ipv6_addr_label_rtnl_register(void)
 		return ret;
 	ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETADDRLABEL,
 				   ip6addrlbl_get,
-				   ip6addrlbl_dump, RTNL_FLAG_DOIT_UNLOCKED);
+				   ip6addrlbl_dump, RTNL_FLAG_DOIT_UNLOCKED |
+						    RTNL_FLAG_DUMP_UNLOCKED);
 	return ret;
 }