[PATCH net-next 2/2] batman-adv: use skb_crc32c() instead of skb_seq_read()

From: Sven Eckelmann <[email protected]>

Make batadv_bla_check_duplist() just use the new function skb_crc32c(),
instead of calling skb_seq_read() with crc32c(). This is faster and
simpler.

Suggested-by: Eric Biggers <[email protected]>
Signed-off-by: Sven Eckelmann <[email protected]>
Signed-off-by: Simon Wunderlich <[email protected]>
---
 net/batman-adv/Kconfig                 |  1 +
 net/batman-adv/bridge_loop_avoidance.c | 51 ++++----------------------
 net/batman-adv/types.h                 |  2 +-
 3 files changed, 10 insertions(+), 44 deletions(-)

diff --git a/net/batman-adv/Kconfig b/net/batman-adv/Kconfig
index c299e2bc87eda..58c408b7a7d9c 100644
--- a/net/batman-adv/Kconfig
+++ b/net/batman-adv/Kconfig
@@ -35,6 +35,7 @@ config BATMAN_ADV_BLA
 	bool "Bridge Loop Avoidance"
 	depends on BATMAN_ADV && INET
 	select CRC16
+	select NET_CRC32C
 	default y
 	help
 	  This option enables BLA (Bridge Loop Avoidance), a mechanism
diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index b992ba12aa247..3dc791c15bf72 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -12,7 +12,6 @@
 #include <linux/compiler.h>
 #include <linux/container_of.h>
 #include <linux/crc16.h>
-#include <linux/crc32.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/etherdevice.h>
@@ -1585,45 +1584,11 @@ int batadv_bla_init(struct batadv_priv *bat_priv)
 	return 0;
 }
 
-/**
- * batadv_skb_crc32() - calculate CRC32 of the whole packet and skip bytes in
- *  the header
- * @skb: skb pointing to fragmented socket buffers
- * @payload_ptr: Pointer to position inside the head buffer of the skb
- *  marking the start of the data to be CRC'ed
- *
- * payload_ptr must always point to an address in the skb head buffer and not to
- * a fragment.
- *
- * Return: big endian crc32c of the checksummed data
- */
-static __be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr)
-{
-	unsigned int to = skb->len;
-	unsigned int consumed = 0;
-	struct skb_seq_state st;
-	unsigned int from;
-	unsigned int len;
-	const u8 *data;
-	u32 crc = 0;
-
-	from = (unsigned int)(payload_ptr - skb->data);
-
-	skb_prepare_seq_read(skb, from, to, &st);
-	while ((len = skb_seq_read(consumed, &data, &st)) != 0) {
-		crc = crc32c(crc, data, len);
-		consumed += len;
-	}
-
-	return htonl(crc);
-}
-
 /**
  * batadv_bla_check_duplist() - Check if a frame is in the broadcast dup.
  * @bat_priv: the bat priv with all the mesh interface information
  * @skb: contains the multicast packet to be checked
- * @payload_ptr: pointer to position inside the head buffer of the skb
- *  marking the start of the data to be CRC'ed
+ * @payload_offset: offset in the skb, marking the start of the data to be CRC'ed
  * @orig: originator mac address, NULL if unknown
  *
  * Check if it is on our broadcast list. Another gateway might have sent the
@@ -1638,16 +1603,18 @@ static __be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr)
  * Return: true if a packet is in the duplicate list, false otherwise.
  */
 static bool batadv_bla_check_duplist(struct batadv_priv *bat_priv,
-				     struct sk_buff *skb, u8 *payload_ptr,
+				     struct sk_buff *skb, int payload_offset,
 				     const u8 *orig)
 {
 	struct batadv_bcast_duplist_entry *entry;
 	bool ret = false;
+	int payload_len;
 	int i, curr;
-	__be32 crc;
+	u32 crc;
 
 	/* calculate the crc ... */
-	crc = batadv_skb_crc32(skb, payload_ptr);
+	payload_len = skb->len - payload_offset;
+	crc = skb_crc32c(skb, payload_offset, payload_len, 0);
 
 	spin_lock_bh(&bat_priv->bla.bcast_duplist_lock);
 
@@ -1727,7 +1694,7 @@ static bool batadv_bla_check_duplist(struct batadv_priv *bat_priv,
 static bool batadv_bla_check_ucast_duplist(struct batadv_priv *bat_priv,
 					   struct sk_buff *skb)
 {
-	return batadv_bla_check_duplist(bat_priv, skb, (u8 *)skb->data, NULL);
+	return batadv_bla_check_duplist(bat_priv, skb, 0, NULL);
 }
 
 /**
@@ -1745,12 +1712,10 @@ bool batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv,
 				    struct sk_buff *skb)
 {
 	struct batadv_bcast_packet *bcast_packet;
-	u8 *payload_ptr;
 
 	bcast_packet = (struct batadv_bcast_packet *)skb->data;
-	payload_ptr = (u8 *)(bcast_packet + 1);
 
-	return batadv_bla_check_duplist(bat_priv, skb, payload_ptr,
+	return batadv_bla_check_duplist(bat_priv, skb, sizeof(*bcast_packet),
 					bcast_packet->orig);
 }
 
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index ae1d7a8dc480f..8fc5fe0e9b053 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -734,7 +734,7 @@ struct batadv_bcast_duplist_entry {
 	u8 orig[ETH_ALEN];
 
 	/** @crc: crc32 checksum of broadcast payload */
-	__be32 crc;
+	u32 crc;
 
 	/** @entrytime: time when the broadcast packet was received */
 	unsigned long entrytime;
-- 
2.47.3