xfrm: Flushing empty SPD generates false events

Observed similar behavior on SPD as previouly seen on SAD flushing..
This fixes it.

cheers,
jamal
commit 428b20432dc31bc2e01a94cd451cf5a2c00d2bf4
Author: Jamal Hadi Salim <hadi@cyberus.ca>
Date:   Thu Feb 11 05:49:38 2010 -0500

    xfrm: Flushing empty SPD generates false events

    To see the effect make sure you have an empty SPD.
    On window1 "ip xfrm mon" and on window2 issue "ip xfrm policy flush"
    You get prompt back in window1 and you see the flush event on window2.
    With this fix, you still get prompt on window1 but no event on window2.
Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/key/af_key.c

@@ -2713,7 +2713,7 @@ static int pfkey_spdflush(struct sock *sk, struct sk_buff *skb, struct sadb_msg
 	audit_info.secid = 0;
 	err = xfrm_policy_flush(net, XFRM_POLICY_TYPE_MAIN, &audit_info);
 	if (err)
-		return err;
+		return 0;
 	c.data.type = XFRM_POLICY_TYPE_MAIN;
 	c.event = XFRM_MSG_FLUSHPOLICY;
 	c.pid = hdr->sadb_msg_pid;

net/xfrm/xfrm_policy.c

@@ -771,7 +771,8 @@ xfrm_policy_flush_secctx_check(struct net *net, u8 type, struct xfrm_audit *audi
 
 int xfrm_policy_flush(struct net *net, u8 type, struct xfrm_audit *audit_info)
 {
-	int dir, err = 0;
+	int dir, err = 0, cnt = 0;
+	struct xfrm_policy *dp;
 
 	write_lock_bh(&xfrm_policy_lock);
 
@@ -789,8 +790,10 @@ int xfrm_policy_flush(struct net *net, u8 type, struct xfrm_audit *audit_info)
 				     &net->xfrm.policy_inexact[dir], bydst) {
 			if (pol->type != type)
 				continue;
-			__xfrm_policy_unlink(pol, dir);
+			dp = __xfrm_policy_unlink(pol, dir);
 			write_unlock_bh(&xfrm_policy_lock);
+			if (dp)
+				cnt++;
 
 			xfrm_audit_policy_delete(pol, 1, audit_info->loginuid,
 						 audit_info->sessionid,
@@ -809,8 +812,10 @@ int xfrm_policy_flush(struct net *net, u8 type, struct xfrm_audit *audit_info)
 					     bydst) {
 				if (pol->type != type)
 					continue;
-				__xfrm_policy_unlink(pol, dir);
+				dp = __xfrm_policy_unlink(pol, dir);
 				write_unlock_bh(&xfrm_policy_lock);
+				if (dp)
+					cnt++;
 
 				xfrm_audit_policy_delete(pol, 1,
 							 audit_info->loginuid,
@@ -824,6 +829,8 @@ int xfrm_policy_flush(struct net *net, u8 type, struct xfrm_audit *audit_info)
 		}
 
 	}
+	if (!cnt)
+		err = -ESRCH;
 	atomic_inc(&flow_cache_genid);
 out:
 	write_unlock_bh(&xfrm_policy_lock);

net/xfrm/xfrm_user.c

@@ -1677,7 +1677,7 @@ static int xfrm_flush_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
 	audit_info.secid = NETLINK_CB(skb).sid;
 	err = xfrm_policy_flush(net, type, &audit_info);
 	if (err)
-		return err;
+		return 0;
 	c.data.type = type;
 	c.event = nlh->nlmsg_type;
 	c.seq = nlh->nlmsg_seq;