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net: pktgen: fix pkt_size 

The commit 879c7220e8 ("net: pktgen: Observe needed_headroom
of the device") increased the 'pkt_overhead' field value by
LL_RESERVED_SPACE.
As a side effect the generated packet size, computed as:

	/* Eth + IPh + UDPh + mpls */
	datalen = pkt_dev->cur_pkt_size - 14 - 20 - 8 -
		  pkt_dev->pkt_overhead;

is decreased by the same value.
The above changed slightly the behavior of existing pktgen users,
and made the procfs interface somewhat inconsistent.
Fix it by restoring the previous pkt_overhead value and using
LL_RESERVED_SPACE as extralen in skb allocation.
Also, change pktgen_alloc_skb() to only partially reserve
the headroom to allow the caller to prefetch from ll header
start.

v1 -> v2:
 - fixed some typos in the comments

Fixes: 879c7220e8 ("net: pktgen: Observe needed_headroom of the device")
Suggested-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2016-09-30 16:56:45 +02:00 committed by David S. Miller
parent b82d44d784
commit 63d75463c9
1 changed files with 10 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
net/core/pktgen.c
View File

@ -2286,7 +2286,7 @@ static void spin(struct pktgen_dev *pkt_dev, ktime_t spin_until)
static inline void set_pkt_overhead(struct pktgen_dev *pkt_dev)
{
pkt_dev->pkt_overhead = LL_RESERVED_SPACE(pkt_dev->odev);
pkt_dev->pkt_overhead = 0;
pkt_dev->pkt_overhead += pkt_dev->nr_labels*sizeof(u32);
pkt_dev->pkt_overhead += VLAN_TAG_SIZE(pkt_dev);
pkt_dev->pkt_overhead += SVLAN_TAG_SIZE(pkt_dev);
@ -2777,13 +2777,13 @@ static void pktgen_finalize_skb(struct pktgen_dev *pkt_dev, struct sk_buff *skb,
}
static struct sk_buff *pktgen_alloc_skb(struct net_device *dev,
struct pktgen_dev *pkt_dev,
unsigned int extralen)
struct pktgen_dev *pkt_dev)
{
unsigned int extralen = LL_RESERVED_SPACE(dev);
struct sk_buff *skb = NULL;
unsigned int size = pkt_dev->cur_pkt_size + 64 + extralen +
pkt_dev->pkt_overhead;
unsigned int size;
size = pkt_dev->cur_pkt_size + 64 + extralen + pkt_dev->pkt_overhead;
if (pkt_dev->flags & F_NODE) {
int node = pkt_dev->node >= 0 ? pkt_dev->node : numa_node_id();
@ -2796,8 +2796,9 @@ static struct sk_buff *pktgen_alloc_skb(struct net_device *dev,
skb = __netdev_alloc_skb(dev, size, GFP_NOWAIT);
}
/* the caller pre-fetches from skb->data and reserves for the mac hdr */
if (likely(skb))
skb_reserve(skb, LL_RESERVED_SPACE(dev));
skb_reserve(skb, extralen - 16);
return skb;
}
@ -2830,16 +2831,14 @@ static struct sk_buff *fill_packet_ipv4(struct net_device *odev,
mod_cur_headers(pkt_dev);
queue_map = pkt_dev->cur_queue_map;
datalen = (odev->hard_header_len + 16) & ~0xf;
skb = pktgen_alloc_skb(odev, pkt_dev, datalen);
skb = pktgen_alloc_skb(odev, pkt_dev);
if (!skb) {
sprintf(pkt_dev->result, "No memory");
return NULL;
}
prefetchw(skb->data);
skb_reserve(skb, datalen);
skb_reserve(skb, 16);
/* Reserve for ethernet and IP header */
eth = (__u8 *) skb_push(skb, 14);
@ -2959,7 +2958,7 @@ static struct sk_buff *fill_packet_ipv6(struct net_device *odev,
mod_cur_headers(pkt_dev);
queue_map = pkt_dev->cur_queue_map;
skb = pktgen_alloc_skb(odev, pkt_dev, 16);
skb = pktgen_alloc_skb(odev, pkt_dev);
if (!skb) {
sprintf(pkt_dev->result, "No memory");
return NULL;