[net-next PATCH v2 1/2] net: pktgen: support injecting packets for qdisc testing

John Fastabend
2016-07-02T21:13:07Z

Add another xmit_mode to pktgen to allow testing xmit functionality
of qdiscs. The new mode "queue_xmit" injects packets at
__dev_queue_xmit() so that qdisc is called.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
---
net/core/pktgen.c | 42 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 40 insertions(+), 2 deletions(-)

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index f74ab9c..bbd118b 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -213,6 +213,7 @@
/* Xmit modes */
#define M_START_XMIT 0 /* Default normal TX */
#define M_NETIF_RECEIVE 1 /* Inject packets into stack */
+#define M_QUEUE_XMIT 2 /* Inject packet into qdisc */

/* If lock -- protects updating of if_list */
#define if_lock(t) spin_lock(&(t->if_lock));
@@ -626,6 +627,8 @@ static int pktgen_if_show(struct seq_file *seq, void *v)

if (pkt_dev->xmit_mode == M_NETIF_RECEIVE)
seq_puts(seq, " xmit_mode: netif_receive\n");
+ else if (pkt_dev->xmit_mode == M_QUEUE_XMIT)
+ seq_puts(seq, " xmit_mode: xmit_queue\n");

seq_puts(seq, " Flags: ");

@@ -1142,8 +1145,10 @@ static ssize_t pktgen_if_write(struct file *file,
return len;

i += len;
- if ((value > 1) && (pkt_dev->xmit_mode == M_START_XMIT) &&
- (!(pkt_dev->odev->priv_flags & IFF_TX_SKB_SHARING)))
+ if ((value > 1) &&
+ ((pkt_dev->xmit_mode == M_QUEUE_XMIT) ||
+ ((pkt_dev->xmit_mode == M_START_XMIT) &&
+ (!(pkt_dev->odev->priv_flags & IFF_TX_SKB_SHARING)))))
return -ENOTSUPP;
pkt_dev->burst = value < 1 ? 1 : value;
sprintf(pg_result, "OK: burst=%d", pkt_dev->burst);
@@ -1198,6 +1203,9 @@ static ssize_t pktgen_if_write(struct file *file,
* at module loading time
*/
pkt_dev->clone_skb = 0;
+ } else if (strcmp(f, "queue_xmit") == 0) {
+ pkt_dev->xmit_mode = M_QUEUE_XMIT;
+ pkt_dev->last_ok = 1;
} else {
sprintf(pg_result,
"xmit_mode -:%s:- unknown\nAvailable modes: %s",
@@ -3434,6 +3442,36 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
#endif
} while (--burst > 0);
goto out; /* Skips xmit_mode M_START_XMIT */
+ } else if (pkt_dev->xmit_mode == M_QUEUE_XMIT) {
+ local_bh_disable();
+ atomic_inc(&pkt_dev->skb->users);
+
+ ret = dev_queue_xmit(pkt_dev->skb);
+ switch (ret) {
+ case NET_XMIT_SUCCESS:
+ pkt_dev->sofar++;
+ pkt_dev->seq_num++;
+ pkt_dev->tx_bytes += pkt_dev->last_pkt_size;
+ break;
+ case NET_XMIT_DROP:
+ case NET_XMIT_CN:
+ /* These are all valid return codes for a qdisc but
+ * indicate packets are being dropped or will likely
+ * be dropped soon.
+ */
+ case NETDEV_TX_BUSY:
+ /* qdisc may call dev_hard_start_xmit directly in cases
+ * where no queues exist e.g. loopback device, virtual
+ * devices, etc. In this case we need to handle
+ * NETDEV_TX_ codes.
+ */
+ default:
+ pkt_dev->errors++;
+ net_info_ratelimited("%s xmit error: %d\n",
+ pkt_dev->odevname, ret);
+ break;
+ }
+ goto out;
}

txq = skb_get_tx_queue(odev, pkt_dev->skb);