can: join filters with per-CPU variables

index 00c13ef..8c75446 100644
@@ -74,6 +74,11 @@ MODULE_ALIAS("can-proto-1");
  * storing the single filter in dfilter, to avoid using dynamic memory.
  */
 
+struct uniqframe {
+	const struct sk_buff *skb;
+	ktime_t tstamp;
+};
+
 struct raw_sock {
 	struct sock sk;
 	int bound;

@@ -86,6 +91,7 @@ struct raw_sock {
 	struct can_filter dfilter; /* default/single filter */
 	struct can_filter *filter; /* pointer to filter(s) */
 	can_err_mask_t err_mask;
+	struct uniqframe __percpu *uniq;
 };
 
 /*

@@ -123,6 +129,15 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
 	if (!ro->fd_frames && oskb->len != CAN_MTU)
 		return;
 
+	/* eliminate multiple filter matches for the same skb */
+	if (this_cpu_ptr(ro->uniq)->skb == oskb &&
+	    ktime_equal(this_cpu_ptr(ro->uniq)->tstamp, oskb->tstamp)) {
+		return;
+	} else {
+		this_cpu_ptr(ro->uniq)->skb = oskb;
+		this_cpu_ptr(ro->uniq)->tstamp = oskb->tstamp;
+	}
+
 	/* clone the given skb to be able to enqueue it into the rcv queue */
 	skb = skb_clone(oskb, GFP_ATOMIC);
 	if (!skb)

@@ -297,6 +312,11 @@ static int raw_init(struct sock *sk)
 	ro->recv_own_msgs    = 0;
 	ro->fd_frames        = 0;
 
+	/* alloc_percpu provides zero'ed memory */
+	ro->uniq = alloc_percpu(struct uniqframe);
+	if (unlikely(!ro->uniq))
+		return -ENOMEM;
+
 	/* set notifier */
 	ro->notifier.notifier_call = raw_notifier;
 

@@ -339,6 +359,7 @@ static int raw_release(struct socket *sock)
 	ro->ifindex = 0;
 	ro->bound   = 0;
 	ro->count   = 0;
+	free_percpu(ro->uniq);
 
 	sock_orphan(sk);
 	sock->sk = NULL;

index 78ec76f..8735f108 100644
@@ -57,6 +57,7 @@ enum {
 	CAN_RAW_LOOPBACK,	/* local loopback (default:on)       */
 	CAN_RAW_RECV_OWN_MSGS,	/* receive my own msgs (default:off) */
 	CAN_RAW_FD_FRAMES,	/* allow CAN FD frames (default:off) */
+	CAN_RAW_JOIN_FILTERS,	/* all filters must match to trigger */
 };
 
 #endif /* !_UAPI_CAN_RAW_H */

index 8c75446..7b94554 100644
@@ -77,6 +77,7 @@ MODULE_ALIAS("can-proto-1");
 struct uniqframe {
 	const struct sk_buff *skb;
 	ktime_t tstamp;
+	unsigned int join_rx_count;
 };
 
 struct raw_sock {

@@ -87,6 +88,7 @@ struct raw_sock {
 	int loopback;
 	int recv_own_msgs;
 	int fd_frames;
+	int join_filters;
 	int count;                 /* number of active filters */
 	struct can_filter dfilter; /* default/single filter */
 	struct can_filter *filter; /* pointer to filter(s) */

@@ -132,10 +134,21 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
 	/* eliminate multiple filter matches for the same skb */
 	if (this_cpu_ptr(ro->uniq)->skb == oskb &&
 	    ktime_equal(this_cpu_ptr(ro->uniq)->tstamp, oskb->tstamp)) {
-		return;
+		if (ro->join_filters) {
+			this_cpu_inc(ro->uniq->join_rx_count);
+			/* drop frame until all enabled filters matched */
+			if (this_cpu_ptr(ro->uniq)->join_rx_count < ro->count)
+				return;
+		} else {
+			return;
+		}
 	} else {
 		this_cpu_ptr(ro->uniq)->skb = oskb;
 		this_cpu_ptr(ro->uniq)->tstamp = oskb->tstamp;
+		this_cpu_ptr(ro->uniq)->join_rx_count = 1;
+		/* drop first frame to check all enabled filters? */
+		if (ro->join_filters && ro->count > 1)
+			return;
 	}
 
 	/* clone the given skb to be able to enqueue it into the rcv queue */

@@ -311,6 +324,7 @@ static int raw_init(struct sock *sk)
 	ro->loopback         = 1;
 	ro->recv_own_msgs    = 0;
 	ro->fd_frames        = 0;
+	ro->join_filters     = 0;
 
 	/* alloc_percpu provides zero'ed memory */
 	ro->uniq = alloc_percpu(struct uniqframe);

@@ -604,6 +618,15 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
 
 		break;
 
+	case CAN_RAW_JOIN_FILTERS:
+		if (optlen != sizeof(ro->join_filters))
+			return -EINVAL;
+
+		if (copy_from_user(&ro->join_filters, optval, optlen))
+			return -EFAULT;
+
+		break;
+
 	default:
 		return -ENOPROTOOPT;
 	}

@@ -668,6 +691,12 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
 		val = &ro->fd_frames;
 		break;
 
+	case CAN_RAW_JOIN_FILTERS:
+		if (len > sizeof(int))
+			len = sizeof(int);
+		val = &ro->join_filters;
+		break;
+
 	default:
 		return -ENOPROTOOPT;
 	}