[net-next,3/8] net/packet: constify prb_lookup_block() and __tpacket_v3_has_room()
diff mbox series

Message ID 20190612165233.109749-4-edumazet@google.com
State Accepted
Delegated to: David Miller
Headers show
Series
  • net/packet: better behavior under DDOS
Related show

Commit Message

Eric Dumazet June 12, 2019, 4:52 p.m. UTC
Goal is to be able to use __tpacket_v3_has_room() without holding
a lock.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/packet/af_packet.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

Patch
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diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 273bffd2130d36cceb9947540a8511a51895874a..5ef63d0c3ad0a184a03429fdd52cad26349647d1 100644
--- 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)