packet: Report fanout status via diag engine

Reported value is the same reported by the FANOUT getsockoption, but
unlike it, the absent fanout setup results in absent nlattr, rather
than in nlattr with zero value. This is done so, since zero fanout
report may mean both -- no fanout, and fanout with both id and type zero.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 42 insertions, 21 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 8a1605ae4029..226b2cdfc339 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -207,24 +207,6 @@ static void prb_fill_vlan_info(struct tpacket_kbdq_core *,
                 struct tpacket3_hdr *);
 static void packet_flush_mclist(struct sock *sk);
 
-#define PACKET_FANOUT_MAX       256
-
-struct packet_fanout {
-#ifdef CONFIG_NET_NS
-        struct net              *net;
-#endif
-        unsigned int            num_members;
-        u16                     id;
-        u8                      type;
-        u8                      defrag;
-        atomic_t                rr_cur;
-        struct list_head        list;
-        struct sock             *arr[PACKET_FANOUT_MAX];
-        spinlock_t              lock;
-        atomic_t                sk_ref;
-        struct packet_type      prot_hook ____cacheline_aligned_in_smp;
-};
-
 struct packet_skb_cb {
         unsigned int origlen;
         union {
@@ -1148,7 +1130,8 @@ static int packet_rcv_fanout(struct sk_buff *skb, struct net_device *dev,
         return po->prot_hook.func(skb, dev, &po->prot_hook, orig_dev);
 }
 
-static DEFINE_MUTEX(fanout_mutex);
+DEFINE_MUTEX(fanout_mutex);
+EXPORT_SYMBOL_GPL(fanout_mutex);
 static LIST_HEAD(fanout_list);
 
 static void __fanout_link(struct sock *sk, struct packet_sock *po)
@@ -1260,9 +1243,9 @@ static void fanout_release(struct sock *sk)
         if (!f)
                 return;
 
+        mutex_lock(&fanout_mutex);
         po->fanout = NULL;
 
-        mutex_lock(&fanout_mutex);
         if (atomic_dec_and_test(&f->sk_ref)) {
                 list_del(&f->list);
                 dev_remove_pack(&f->prot_hook);
diff --git a/net/packet/diag.c b/net/packet/diag.c
index e3975e4d458c..bc33fbe8a5ef 100644
--- a/net/packet/diag.c
+++ b/net/packet/diag.c
@@ -109,6 +109,22 @@ static int pdiag_put_rings_cfg(struct packet_sock *po, struct sk_buff *skb)
         return ret;
 }
 
+static int pdiag_put_fanout(struct packet_sock *po, struct sk_buff *nlskb)
+{
+        int ret = 0;
+
+        mutex_lock(&fanout_mutex);
+        if (po->fanout) {
+                u32 val;
+
+                val = (u32)po->fanout->id | ((u32)po->fanout->type << 16);
+                ret = nla_put_u32(nlskb, PACKET_DIAG_FANOUT, val);
+        }
+        mutex_unlock(&fanout_mutex);
+
+        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)
 {
@@ -139,6 +155,10 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct packet_diag
                         pdiag_put_rings_cfg(po, skb))
                 goto out_nlmsg_trim;
 
+        if ((req->pdiag_show & PACKET_SHOW_FANOUT) &&
+                        pdiag_put_fanout(po, skb))
+                goto out_nlmsg_trim;
+
         return nlmsg_end(skb, nlh);
 
 out_nlmsg_trim:
diff --git a/net/packet/internal.h b/net/packet/internal.h
index 2c5fca28b242..44945f6b7252 100644
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -67,7 +67,25 @@ struct packet_ring_buffer {
         atomic_t                pending;
 };
 
-struct packet_fanout;
+extern struct mutex fanout_mutex;
+#define PACKET_FANOUT_MAX       256
+
+struct packet_fanout {
+#ifdef CONFIG_NET_NS
+        struct net              *net;
+#endif
+        unsigned int            num_members;
+        u16                     id;
+        u8                      type;
+        u8                      defrag;
+        atomic_t                rr_cur;
+        struct list_head        list;
+        struct sock             *arr[PACKET_FANOUT_MAX];
+        spinlock_t              lock;
+        atomic_t                sk_ref;
+        struct packet_type      prot_hook ____cacheline_aligned_in_smp;
+};
+
 struct packet_sock {
         /* struct sock has to be the first member of packet_sock */
         struct sock             sk;