diff mbox

[RFC] netlink: send exterr cookie on success

Message ID 20170407194402.4181-1-johannes@sipsolutions.net
State RFC, archived
Delegated to: David Miller
Headers show

Commit Message

Johannes Berg April 7, 2017, 7:44 p.m. UTC 
From: Johannes Berg <johannes.berg@intel.com>

This is for Jamal, it allows the subsystem to return an arbitrary
cookie to identify a new object/operation, perhaps to delete or
cancel it later.

This is actually something we use a lot in wifi too, though I'm
not sure how we could do the backport necessary for that (since
we sadly need to ship to all kinds of old kernels)

Also contains the missing (err) check I pointed out - I'll squash
this patch into the first of the exterr after I test it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 include/linux/netlink.h      |  2 ++
 include/uapi/linux/netlink.h |  4 ++++
 net/netlink/af_netlink.c     | 28 +++++++++++++++++++---------
 3 files changed, 25 insertions(+), 9 deletions(-)

Comments

Jiri Benc April 8, 2017, 3:28 p.m. UTC | #1 
On Fri,  7 Apr 2017 21:44:02 +0200, Johannes Berg wrote:
> @@ -67,6 +67,8 @@ struct netlink_ext_err {
>  	u32 ext_code;
>  	u32 msg_offset;
>  	u16 attr;
> +	const u8 *cookie;
> +	u8 cookie_len;
>  };

Perhaps the structure should be named just "netlink_ext" or so? It
seems it'll pick up some non-error related usage, such as the cookies
here or, in the future, flags indicating how the message should be
parsed.

Thanks,

 Jiri
Johannes Berg April 8, 2017, 3:50 p.m. UTC | #2 
On Sat, 2017-04-08 at 11:28 -0400, Jiri Benc wrote:
> Perhaps the structure should be named just "netlink_ext" or so? It
> seems it'll pick up some non-error related usage, such as the cookies
> here or, in the future, flags indicating how the message should be
> parsed.

Fair point, I'll call it netlink_ext_ack.

johannes
diff mbox

Patch

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 662f343dc68b..76a0b0a22349 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -67,6 +67,8 @@  struct netlink_ext_err {
 	u32 ext_code;
 	u32 msg_offset;
 	u16 attr;
+	const u8 *cookie;
+	u8 cookie_len;
 };
 
 extern void netlink_kernel_release(struct sock *sk);
diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h
index 0ef970e6f9f5..72a398e0f332 100644
--- a/include/uapi/linux/netlink.h
+++ b/include/uapi/linux/netlink.h
@@ -119,6 +119,9 @@  struct nlmsgerr {
  * @NLMSGERR_ATTR_CODE: extended per-subsystem error code (u32)
  * @NLMSGERR_ATTR_ATTR: top-level attribute that caused the error
  *	(or is missing, u16)
+ * @NLMSGERR_ATTR_COOKIE: arbitrary subsystem specific cookie to
+ *	be used - in the success case - to identify a created
+ *	object or operation or similar (binary)
  */
 enum nlmsgerr_attrs {
 	NLMSGERR_ATTR_UNUSED,
@@ -126,6 +129,7 @@  enum nlmsgerr_attrs {
 	NLMSGERR_ATTR_OFFS,
 	NLMSGERR_ATTR_CODE,
 	NLMSGERR_ATTR_ATTR,
+	NLMSGERR_ATTR_COOKIE,
 };
 
 #define NETLINK_ADD_MEMBERSHIP		1
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 532d906af3be..6b256e540bc1 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2277,6 +2277,9 @@  void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
 			if (exterr && exterr->attr)
 				payload += nla_total_size(sizeof(u16));
 		}
+	} else if (nlk->flags & NETLINK_F_EXT_ACK) {
+		if (exterr && exterr->cookie_len)
+			payload += nla_total_size(exterr->cookie_len);
 	}
 
 	skb = nlmsg_new(payload, GFP_KERNEL);
@@ -2301,15 +2304,22 @@  void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
 	memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
 
 	if (nlk->flags & NETLINK_F_EXT_ACK) {
-		if (exterr && exterr->msg)
-			WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG,
-					       exterr->msg));
-		if (exterr && exterr->msg_offset)
-			WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
-					    exterr->msg_offset));
-		if (exterr && exterr->attr)
-			WARN_ON(nla_put_u16(skb, NLMSGERR_ATTR_ATTR,
-					    exterr->attr));
+		if (err) {
+			if (exterr && exterr->msg)
+				WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG,
+						       exterr->msg));
+			if (exterr && exterr->msg_offset)
+				WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
+						    exterr->msg_offset));
+			if (exterr && exterr->attr)
+				WARN_ON(nla_put_u16(skb, NLMSGERR_ATTR_ATTR,
+						    exterr->attr));
+		} else {
+			if (exterr && exterr->attr)
+				WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,
+						exterr->cookie_len,
+						exterr->cookie));
+		}
 	}
 
 	netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid, MSG_DONTWAIT);