net/packet: constify packet_lookup_frame() and __tpacket_has_room()
Goal is to be able to use __tpacket_has_room() without holding a lock.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 66fcfd5..273bffd 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -460,10 +460,10 @@ static __u32 __packet_set_timestamp(struct packet_sock *po, void *frame,
return ts_status;
}
-static void *packet_lookup_frame(struct packet_sock *po,
- struct packet_ring_buffer *rb,
- unsigned int position,
- int status)
+static void *packet_lookup_frame(const struct packet_sock *po,
+ const struct packet_ring_buffer *rb,
+ unsigned int position,
+ int status)
{
unsigned int pg_vec_pos, frame_offset;
union tpacket_uhdr h;
@@ -1198,12 +1198,12 @@ static void packet_free_pending(struct packet_sock *po)
#define ROOM_LOW 0x1
#define ROOM_NORMAL 0x2
-static bool __tpacket_has_room(struct packet_sock *po, int pow_off)
+static bool __tpacket_has_room(const struct packet_sock *po, int pow_off)
{
int idx, len;
- len = po->rx_ring.frame_max + 1;
- idx = po->rx_ring.head;
+ len = READ_ONCE(po->rx_ring.frame_max) + 1;
+ idx = READ_ONCE(po->rx_ring.head);
if (pow_off)
idx += len >> pow_off;
if (idx >= len)