We can use skb_cow instead of a handwritten function to test and create a writable skb buffer. This also allows us to pre-allocate headroom to be able to send the data without re-allocating the buffer again to add the ethernet header.
Signed-off-by: Sven Eckelmann <[email protected]> --- batman-adv/routing.c | 77 +++++++++++++++---------------------------------- 1 files changed, 24 insertions(+), 53 deletions(-) diff --git a/batman-adv/routing.c b/batman-adv/routing.c index 2764122..7667c55 100644 --- a/batman-adv/routing.c +++ b/batman-adv/routing.c @@ -754,7 +754,6 @@ int recv_bat_packet(struct sk_buff *skb, { struct ethhdr *ethhdr; unsigned long flags; - struct sk_buff *skb_old; /* drop packet if it has not necessary minimum size */ if (skb_headlen(skb) < sizeof(struct batman_packet)) @@ -770,18 +769,11 @@ int recv_bat_packet(struct sk_buff *skb, if (is_bcast(ethhdr->h_source)) return NET_RX_DROP; - /* TODO: we use headlen instead of "length", because - * only this data is paged in. */ - /* create a copy of the skb, if needed, to modify it. */ - if (!skb_clone_writable(skb, skb_headlen(skb))) { - skb_old = skb; - skb = skb_copy(skb, GFP_ATOMIC); - if (!skb) - return NET_RX_DROP; - ethhdr = (struct ethhdr *)skb_mac_header(skb); - kfree_skb(skb_old); - } + if (skb_cow(skb, 0) < 0) + return NET_RX_DROP; + + ethhdr = (struct ethhdr *)skb_mac_header(skb); spin_lock_irqsave(&orig_hash_lock, flags); receive_aggr_bat_packet(ethhdr, @@ -801,7 +793,6 @@ static int recv_my_icmp_packet(struct sk_buff *skb, size_t icmp_len) struct orig_node *orig_node; struct icmp_packet_rr *icmp_packet; struct ethhdr *ethhdr; - struct sk_buff *skb_old; struct batman_if *batman_if; int ret; unsigned long flags; @@ -836,16 +827,11 @@ static int recv_my_icmp_packet(struct sk_buff *skb, size_t icmp_len) spin_unlock_irqrestore(&orig_hash_lock, flags); /* create a copy of the skb, if needed, to modify it. */ - skb_old = NULL; - if (!skb_clone_writable(skb, icmp_len)) { - skb_old = skb; - skb = skb_copy(skb, GFP_ATOMIC); - if (!skb) - return NET_RX_DROP; - icmp_packet = (struct icmp_packet_rr *)skb->data; - ethhdr = (struct ethhdr *)skb_mac_header(skb); - kfree_skb(skb_old); - } + if (skb_cow(skb, sizeof(struct ethhdr)) < 0) + return NET_RX_DROP; + + icmp_packet = (struct icmp_packet_rr *)skb->data; + ethhdr = (struct ethhdr *)skb_mac_header(skb); memcpy(icmp_packet->dst, icmp_packet->orig, ETH_ALEN); memcpy(icmp_packet->orig, @@ -869,7 +855,6 @@ static int recv_icmp_ttl_exceeded(struct sk_buff *skb, size_t icmp_len) struct orig_node *orig_node; struct icmp_packet *icmp_packet; struct ethhdr *ethhdr; - struct sk_buff *skb_old; struct batman_if *batman_if; int ret; unsigned long flags; @@ -905,15 +890,11 @@ static int recv_icmp_ttl_exceeded(struct sk_buff *skb, size_t icmp_len) spin_unlock_irqrestore(&orig_hash_lock, flags); /* create a copy of the skb, if needed, to modify it. */ - if (!skb_clone_writable(skb, icmp_len)) { - skb_old = skb; - skb = skb_copy(skb, GFP_ATOMIC); - if (!skb) - return NET_RX_DROP; - icmp_packet = (struct icmp_packet *) skb->data; - ethhdr = (struct ethhdr *)skb_mac_header(skb); - kfree_skb(skb_old); - } + if (skb_cow(skb, sizeof(struct ethhdr)) < 0) + return NET_RX_DROP; + + icmp_packet = (struct icmp_packet *) skb->data; + ethhdr = (struct ethhdr *)skb_mac_header(skb); memcpy(icmp_packet->dst, icmp_packet->orig, ETH_ALEN); memcpy(icmp_packet->orig, @@ -936,7 +917,6 @@ int recv_icmp_packet(struct sk_buff *skb) struct icmp_packet_rr *icmp_packet; struct ethhdr *ethhdr; struct orig_node *orig_node; - struct sk_buff *skb_old; struct batman_if *batman_if; int hdr_size = sizeof(struct icmp_packet); int ret; @@ -1002,15 +982,11 @@ int recv_icmp_packet(struct sk_buff *skb) spin_unlock_irqrestore(&orig_hash_lock, flags); /* create a copy of the skb, if needed, to modify it. */ - if (!skb_clone_writable(skb, hdr_size)) { - skb_old = skb; - skb = skb_copy(skb, GFP_ATOMIC); - if (!skb) - return NET_RX_DROP; - icmp_packet = (struct icmp_packet_rr *)skb->data; - ethhdr = (struct ethhdr *)skb_mac_header(skb); - kfree_skb(skb_old); - } + if (skb_cow(skb, sizeof(struct ethhdr)) < 0) + return NET_RX_DROP; + + icmp_packet = (struct icmp_packet_rr *)skb->data; + ethhdr = (struct ethhdr *)skb_mac_header(skb); /* decrement ttl */ icmp_packet->ttl--; @@ -1149,7 +1125,6 @@ static int route_unicast_packet(struct sk_buff *skb, struct batman_if *recv_if, struct orig_node *orig_node; struct neigh_node *router; struct batman_if *batman_if; - struct sk_buff *skb_old; uint8_t dstaddr[ETH_ALEN]; unsigned long flags; struct unicast_packet *unicast_packet = @@ -1185,15 +1160,11 @@ static int route_unicast_packet(struct sk_buff *skb, struct batman_if *recv_if, spin_unlock_irqrestore(&orig_hash_lock, flags); /* create a copy of the skb, if needed, to modify it. */ - if (!skb_clone_writable(skb, hdr_size)) { - skb_old = skb; - skb = skb_copy(skb, GFP_ATOMIC); - if (!skb) - return NET_RX_DROP; - unicast_packet = (struct unicast_packet *) skb->data; - ethhdr = (struct ethhdr *)skb_mac_header(skb); - kfree_skb(skb_old); - } + if (skb_cow(skb, sizeof(struct ethhdr)) < 0) + return NET_RX_DROP; + + unicast_packet = (struct unicast_packet *) skb->data; + ethhdr = (struct ethhdr *)skb_mac_header(skb); /* decrement ttl */ unicast_packet->ttl--; -- 1.7.1
