diff mbox series

[net-next,3/4] netlink: support all extack types in dumps

Message ID 20240420023543.3300306-4-kuba@kernel.org (mailing list archive)
State New
Headers show
Series netdev: support dumping a single netdev in qstats | expand

Commit Message

Jakub Kicinski April 20, 2024, 2:35 a.m. UTC 
Note that when this commit message refers to netlink dump
it only means the actual dumping part, the parsing / dump
start is handled by the same code as "doit".

Commit 4a19edb60d02 ("netlink: Pass extack to dump handlers")
added support for returning extack messages from dump handlers,
but left out other extack info, e.g. bad attribute.

This used to be fine because until YNL we had little practical
use for the machine readable attributes, and only messages were
used in practice.

YNL flips the preference 180 degrees, it's now much more useful
to point to a bad attr with NL_SET_BAD_ATTR() than type
an English message saying "attribute XYZ is $reason-why-bad".

Support all of extack. The fact that extack only gets added if
it fits remains unaddressed.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 net/netlink/af_netlink.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

Comments

David Ahern April 21, 2024, 1 a.m. UTC | #1 
On 4/19/24 8:35 PM, Jakub Kicinski wrote:
> Note that when this commit message refers to netlink dump
> it only means the actual dumping part, the parsing / dump
> start is handled by the same code as "doit".
> 
> Commit 4a19edb60d02 ("netlink: Pass extack to dump handlers")
> added support for returning extack messages from dump handlers,
> but left out other extack info, e.g. bad attribute.
> 
> This used to be fine because until YNL we had little practical
> use for the machine readable attributes, and only messages were
> used in practice.
> 
> YNL flips the preference 180 degrees, it's now much more useful
> to point to a bad attr with NL_SET_BAD_ATTR() than type
> an English message saying "attribute XYZ is $reason-why-bad".
> 
> Support all of extack. The fact that extack only gets added if
> it fits remains unaddressed.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
>  net/netlink/af_netlink.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>
diff mbox series

Patch

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index c5bb09597831..fa9c090cf629 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2198,7 +2198,7 @@  netlink_ack_tlv_len(struct netlink_sock *nlk, int err,
 
 static void
 netlink_ack_tlv_fill(struct sk_buff *in_skb, struct sk_buff *skb,
-		     struct nlmsghdr *nlh, int err,
+		     const struct nlmsghdr *nlh, int err,
 		     const struct netlink_ext_ack *extack)
 {
 	if (extack->_msg)
@@ -2214,7 +2214,7 @@  netlink_ack_tlv_fill(struct sk_buff *in_skb, struct sk_buff *skb,
 	    !WARN_ON((u8 *)extack->bad_attr < in_skb->data ||
 		     (u8 *)extack->bad_attr >= in_skb->data + in_skb->len))
 		WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
-				    (u8 *)extack->bad_attr - (u8 *)nlh));
+				    (u8 *)extack->bad_attr - (const u8 *)nlh));
 	if (extack->policy)
 		netlink_policy_dump_write_attr(skb, extack->policy,
 					       NLMSGERR_ATTR_POLICY);
@@ -2225,7 +2225,7 @@  netlink_ack_tlv_fill(struct sk_buff *in_skb, struct sk_buff *skb,
 	    !WARN_ON((u8 *)extack->miss_nest < in_skb->data ||
 		     (u8 *)extack->miss_nest > in_skb->data + in_skb->len))
 		WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_MISS_NEST,
-				    (u8 *)extack->miss_nest - (u8 *)nlh));
+				    (u8 *)extack->miss_nest - (const u8 *)nlh));
 }
 
 /*
@@ -2238,6 +2238,7 @@  static int netlink_dump_done(struct netlink_sock *nlk, struct sk_buff *skb,
 			     struct netlink_ext_ack *extack)
 {
 	struct nlmsghdr *nlh;
+	size_t extack_len;
 
 	nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(nlk->dump_done_errno),
 			       NLM_F_MULTI | cb->answer_flags);
@@ -2247,10 +2248,14 @@  static int netlink_dump_done(struct netlink_sock *nlk, struct sk_buff *skb,
 	nl_dump_check_consistent(cb, nlh);
 	memcpy(nlmsg_data(nlh), &nlk->dump_done_errno, sizeof(nlk->dump_done_errno));
 
-	if (extack->_msg && test_bit(NETLINK_F_EXT_ACK, &nlk->flags)) {
+	extack_len = netlink_ack_tlv_len(nlk, nlk->dump_done_errno, extack);
+	if (extack_len) {
 		nlh->nlmsg_flags |= NLM_F_ACK_TLVS;
-		if (!nla_put_string(skb, NLMSGERR_ATTR_MSG, extack->_msg))
+		if (skb_tailroom(skb) >= extack_len) {
+			netlink_ack_tlv_fill(cb->skb, skb, cb->nlh,
+					     nlk->dump_done_errno, extack);
 			nlmsg_end(skb, nlh);
+		}
 	}
 
 	return 0;