packet: Report rings cfg via diag engine

One extension bit may result in two nlattrs -- one per ring type.
If some ring type is not configured, then the respective nlatts
will be empty.

The structure reported contains the data, that is given to the
corresponding ring setup socket option.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/packet_diag.h

@@ -14,6 +14,7 @@ struct packet_diag_req {
 
 #define PACKET_SHOW_INFO	0x00000001 /* Basic packet_sk information */
 #define PACKET_SHOW_MCLIST	0x00000002 /* A set of packet_diag_mclist-s */
+#define PACKET_SHOW_RING_CFG	0x00000004 /* Rings configuration parameters */
 
 struct packet_diag_msg {
 	__u8	pdiag_family;
@@ -27,6 +28,8 @@ struct packet_diag_msg {
 enum {
 	PACKET_DIAG_INFO,
 	PACKET_DIAG_MCLIST,
+	PACKET_DIAG_RX_RING,
+	PACKET_DIAG_TX_RING,
 
 	PACKET_DIAG_MAX,
 };
@@ -54,4 +57,14 @@ struct packet_diag_mclist {
 	__u8	pdmc_addr[MAX_ADDR_LEN];
 };
 
+struct packet_diag_ring {
+	__u32	pdr_block_size;
+	__u32	pdr_block_nr;
+	__u32	pdr_frame_size;
+	__u32	pdr_frame_nr;
+	__u32	pdr_retire_tmo;
+	__u32	pdr_sizeof_priv;
+	__u32	pdr_features;
+};
+
 #endif

net/packet/diag.c

@@ -67,12 +67,54 @@ static int pdiag_put_mclist(const struct packet_sock *po, struct sk_buff *nlskb)
 	return 0;
 }
 
+static int pdiag_put_ring(struct packet_ring_buffer *ring, int ver, int nl_type,
+		struct sk_buff *nlskb)
+{
+	struct packet_diag_ring pdr;
+
+	if (!ring->pg_vec || ((ver > TPACKET_V2) &&
+				(nl_type == PACKET_DIAG_TX_RING)))
+		return 0;
+
+	pdr.pdr_block_size = ring->pg_vec_pages << PAGE_SHIFT;
+	pdr.pdr_block_nr = ring->pg_vec_len;
+	pdr.pdr_frame_size = ring->frame_size;
+	pdr.pdr_frame_nr = ring->frame_max + 1;
+
+	if (ver > TPACKET_V2) {
+		pdr.pdr_retire_tmo = ring->prb_bdqc.retire_blk_tov;
+		pdr.pdr_sizeof_priv = ring->prb_bdqc.blk_sizeof_priv;
+		pdr.pdr_features = ring->prb_bdqc.feature_req_word;
+	} else {
+		pdr.pdr_retire_tmo = 0;
+		pdr.pdr_sizeof_priv = 0;
+		pdr.pdr_features = 0;
+	}
+
+	return nla_put(nlskb, nl_type, sizeof(pdr), &pdr);
+}
+
+static int pdiag_put_rings_cfg(struct packet_sock *po, struct sk_buff *skb)
+{
+	int ret;
+
+	mutex_lock(&po->pg_vec_lock);
+	ret = pdiag_put_ring(&po->rx_ring, po->tp_version,
+			PACKET_DIAG_RX_RING, skb);
+	if (!ret)
+		ret = pdiag_put_ring(&po->tx_ring, po->tp_version,
+				PACKET_DIAG_TX_RING, skb);
+	mutex_unlock(&po->pg_vec_lock);
+
+	return ret;
+}
+
 static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct packet_diag_req *req,
 		u32 pid, u32 seq, u32 flags, int sk_ino)
 {
 	struct nlmsghdr *nlh;
 	struct packet_diag_msg *rp;
-	const struct packet_sock *po = pkt_sk(sk);
+	struct packet_sock *po = pkt_sk(sk);
 
 	nlh = nlmsg_put(skb, pid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rp), flags);
 	if (!nlh)
@@ -93,6 +135,10 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct packet_diag
 			pdiag_put_mclist(po, skb))
 		goto out_nlmsg_trim;
 
+	if ((req->pdiag_show & PACKET_SHOW_RING_CFG) &&
+			pdiag_put_rings_cfg(po, skb))
+		goto out_nlmsg_trim;
+
 	return nlmsg_end(skb, nlh);
 
 out_nlmsg_trim: