net/packet: constify prb_lookup_block() and __tpacket_v3_has_room()

Goal is to be able to use __tpacket_v3_has_room() without holding a lock. Signed-off-by: Eric Dumazet <[email protected]> Signed-off-by: David S. Miller <[email protected]>
wafgo · Jun 15, 2019 · dcf70ce · dcf70ce
1 parent d4b5bd9
commit dcf70ce
Showing 1 changed file with 7 additions and 7 deletions.
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
@@ -1082,10 +1082,10 @@ static void *packet_current_rx_frame(struct packet_sock *po,
 	}
 }
 
-static void *prb_lookup_block(struct packet_sock *po,
-				     struct packet_ring_buffer *rb,
-				     unsigned int idx,
-				     int status)
+static void *prb_lookup_block(const struct packet_sock *po,
+			      const struct packet_ring_buffer *rb,
+			      unsigned int idx,
+			      int status)
 {
 	struct tpacket_kbdq_core *pkc  = GET_PBDQC_FROM_RB(rb);
 	struct tpacket_block_desc *pbd = GET_PBLOCK_DESC(pkc, idx);
@@ -1211,12 +1211,12 @@ static bool __tpacket_has_room(const struct packet_sock *po, int pow_off)
 	return packet_lookup_frame(po, &po->rx_ring, idx, TP_STATUS_KERNEL);
 }
 
-static bool __tpacket_v3_has_room(struct packet_sock *po, int pow_off)
+static bool __tpacket_v3_has_room(const struct packet_sock *po, int pow_off)
 {
 	int idx, len;
 
-	len = po->rx_ring.prb_bdqc.knum_blocks;
-	idx = po->rx_ring.prb_bdqc.kactive_blk_num;
+	len = READ_ONCE(po->rx_ring.prb_bdqc.knum_blocks);
+	idx = READ_ONCE(po->rx_ring.prb_bdqc.kactive_blk_num);
 	if (pow_off)
 		idx += len >> pow_off;
 	if (idx >= len)