[PATCH v2 net-next 6/8] vmxnet3: limit number of TXDs used for TSO packet

Ronak Doshi
2022-06-07T08:47:12Z

Currently, vmxnet3 does not have a limit on number of descriptors
used for a TSO packet. However, with UPT, for hardware performance
reasons, this patch limits the number of transmit descriptors to 24
for a TSO packet.

Signed-off-by: Ronak Doshi <doshir@vmware.com>
Acked-by: Guolin Yang <gyang@vmware.com>
---
drivers/net/vmxnet3/vmxnet3_defs.h | 2 ++
drivers/net/vmxnet3/vmxnet3_drv.c | 17 +++++++++++++++++
2 files changed, 19 insertions(+)

diff --git a/drivers/net/vmxnet3/vmxnet3_defs.h b/drivers/net/vmxnet3/vmxnet3_defs.h
index 415e4c9993ef..cb9dc72f2b3d 100644
--- a/drivers/net/vmxnet3/vmxnet3_defs.h
+++ b/drivers/net/vmxnet3/vmxnet3_defs.h
@@ -400,6 +400,8 @@ union Vmxnet3_GenericDesc {

/* max # of tx descs for a non-tso pkt */
#define VMXNET3_MAX_TXD_PER_PKT 16
+/* max # of tx descs for a tso pkt */
+#define VMXNET3_MAX_TSO_TXD_PER_PKT 24

/* Max size of a single rx buffer */
#define VMXNET3_MAX_RX_BUF_SIZE ((1 << 14) - 1)
diff --git a/drivers/net/vmxnet3/vmxnet3_drv.c b/drivers/net/vmxnet3/vmxnet3_drv.c
index 2ba263966989..6e013ae0b5ea 100644
--- a/drivers/net/vmxnet3/vmxnet3_drv.c
+++ b/drivers/net/vmxnet3/vmxnet3_drv.c
@@ -1061,6 +1061,23 @@ vmxnet3_tq_xmit(struct sk_buff *skb, struct vmxnet3_tx_queue *tq,
}
tq->stats.copy_skb_header++;
}
+ if (unlikely(count > VMXNET3_MAX_TSO_TXD_PER_PKT)) {
+ /* tso pkts must not use more than
+ * VMXNET3_MAX_TSO_TXD_PER_PKT entries
+ */
+ if (skb_linearize(skb) != 0) {
+ tq->stats.drop_too_many_frags++;
+ goto drop_pkt;
+ }
+ tq->stats.linearized++;
+
+ /* recalculate the # of descriptors to use */
+ count = VMXNET3_TXD_NEEDED(skb_headlen(skb)) + 1;
+ if (unlikely(count > VMXNET3_MAX_TSO_TXD_PER_PKT)) {
+ tq->stats.drop_too_many_frags++;
+ goto drop_pkt;
+ }
+ }
if (skb->encapsulation) {
vmxnet3_prepare_inner_tso(skb, &ctx);
} else {
--
2.11.0