[Intel-wired-lan] [PATCH] i40e: add support for XDP_REDIRECT
Björn Töpel
bjorn.topel at gmail.com
Wed Mar 21 16:15:37 UTC 2018
From: Björn Töpel <bjorn.topel at intel.com>
The driver now acts upon the XDP_REDIRECT return action. Two new ndos
are implemented, ndo_xdp_xmit and ndo_xdp_flush.
XDP_REDIRECT action enables XDP program to redirect frames to other
netdevs. The target redirect/forward netdev might release the XDP data
page within the ndo_xdp_xmit function (triggered by xdp_do_redirect),
which meant that the i40e page count logic had to be tweaked.
An example. i40e_clean_rx_irq is entered, and one rx_buffer is pulled
from the hardware descriptor ring. Say that the actual page refcount
is 1. XDP is enabled, and the redirect action is triggered. The target
netdev ndo_xdp_xmit decreases the page refcount, resulting in the page
being freed. The prior assumption was that the function owned the page
until i40e_put_rx_buffer was called, increasing the refcount again.
Now, we don't allow a refcount less than 2. Another option would be
calling xdp_do_redirect *after* i40e_put_rx_buffer, but that would
have required new/more conditionals.
Signed-off-by: Björn Töpel <bjorn.topel at intel.com>
---
drivers/net/ethernet/intel/i40e/i40e_main.c | 2 +
drivers/net/ethernet/intel/i40e/i40e_txrx.c | 83 +++++++++++++++++++++++------
drivers/net/ethernet/intel/i40e/i40e_txrx.h | 2 +
3 files changed, 72 insertions(+), 15 deletions(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 79ab52276d12..2fb4261b4fd9 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -11815,6 +11815,8 @@ static const struct net_device_ops i40e_netdev_ops = {
.ndo_bridge_getlink = i40e_ndo_bridge_getlink,
.ndo_bridge_setlink = i40e_ndo_bridge_setlink,
.ndo_bpf = i40e_xdp,
+ .ndo_xdp_xmit = i40e_xdp_xmit,
+ .ndo_xdp_flush = i40e_xdp_flush,
};
/**
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index c6972bd07e49..2106ae04d053 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -1589,8 +1589,8 @@ static bool i40e_alloc_mapped_page(struct i40e_ring *rx_ring,
bi->page = page;
bi->page_offset = i40e_rx_offset(rx_ring);
- /* initialize pagecnt_bias to 1 representing we fully own page */
- bi->pagecnt_bias = 1;
+ page_ref_add(page, USHRT_MAX - 1);
+ bi->pagecnt_bias = USHRT_MAX;
return true;
}
@@ -1956,8 +1956,8 @@ static bool i40e_can_reuse_rx_page(struct i40e_rx_buffer *rx_buffer)
* the pagecnt_bias and page count so that we fully restock the
* number of references the driver holds.
*/
- if (unlikely(!pagecnt_bias)) {
- page_ref_add(page, USHRT_MAX);
+ if (unlikely(pagecnt_bias == 1)) {
+ page_ref_add(page, USHRT_MAX - 1);
rx_buffer->pagecnt_bias = USHRT_MAX;
}
@@ -2215,7 +2215,7 @@ static int i40e_xmit_xdp_ring(struct xdp_buff *xdp,
static struct sk_buff *i40e_run_xdp(struct i40e_ring *rx_ring,
struct xdp_buff *xdp)
{
- int result = I40E_XDP_PASS;
+ int err, result = I40E_XDP_PASS;
struct i40e_ring *xdp_ring;
struct bpf_prog *xdp_prog;
u32 act;
@@ -2234,6 +2234,10 @@ static struct sk_buff *i40e_run_xdp(struct i40e_ring *rx_ring,
xdp_ring = rx_ring->vsi->xdp_rings[rx_ring->queue_index];
result = i40e_xmit_xdp_ring(xdp, xdp_ring);
break;
+ case XDP_REDIRECT:
+ err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog);
+ result = !err ? I40E_XDP_TX : I40E_XDP_CONSUMED;
+ break;
default:
bpf_warn_invalid_xdp_action(act);
case XDP_ABORTED:
@@ -2269,6 +2273,16 @@ static void i40e_rx_buffer_flip(struct i40e_ring *rx_ring,
#endif
}
+static inline void i40e_xdp_ring_update_tail(struct i40e_ring *xdp_ring)
+{
+ /* Force memory writes to complete before letting h/w
+ * know there are new descriptors to fetch.
+ */
+ wmb();
+
+ writel(xdp_ring->next_to_use, xdp_ring->tail);
+}
+
/**
* i40e_clean_rx_irq - Clean completed descriptors from Rx ring - bounce buf
* @rx_ring: rx descriptor ring to transact packets on
@@ -2403,16 +2417,9 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
}
if (xdp_xmit) {
- struct i40e_ring *xdp_ring;
-
- xdp_ring = rx_ring->vsi->xdp_rings[rx_ring->queue_index];
-
- /* Force memory writes to complete before letting h/w
- * know there are new descriptors to fetch.
- */
- wmb();
-
- writel(xdp_ring->next_to_use, xdp_ring->tail);
+ i40e_xdp_ring_update_tail(
+ rx_ring->vsi->xdp_rings[rx_ring->queue_index]);
+ xdp_do_flush_map();
}
rx_ring->skb = skb;
@@ -3660,3 +3667,49 @@ netdev_tx_t i40e_lan_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
return i40e_xmit_frame_ring(skb, tx_ring);
}
+
+/**
+ * i40e_xdp_xmit - Implements ndo_xdp_xmit
+ * @dev: netdev
+ * @xdp: XDP buffer
+ *
+ * Returns Zero if sent, else an error code
+ **/
+int i40e_xdp_xmit(struct net_device *dev, struct xdp_buff *xdp)
+{
+ struct i40e_netdev_priv *np = netdev_priv(dev);
+ unsigned int queue_index = smp_processor_id();
+ struct i40e_vsi *vsi = np->vsi;
+ int err;
+
+ if (test_bit(__I40E_VSI_DOWN, vsi->state))
+ return -EINVAL;
+
+ if (!i40e_enabled_xdp_vsi(vsi) || queue_index >= vsi->num_queue_pairs)
+ return -EINVAL;
+
+ err = i40e_xmit_xdp_ring(xdp, vsi->xdp_rings[queue_index]);
+ if (err != I40E_XDP_TX)
+ return -ENOMEM;
+
+ return 0;
+}
+
+/**
+ * i40e_xdp_flush - Implements ndo_xdp_flush
+ * @dev: netdev
+ **/
+void i40e_xdp_flush(struct net_device *dev)
+{
+ struct i40e_netdev_priv *np = netdev_priv(dev);
+ unsigned int queue_index = smp_processor_id();
+ struct i40e_vsi *vsi = np->vsi;
+
+ if (test_bit(__I40E_VSI_DOWN, vsi->state))
+ return;
+
+ if (!i40e_enabled_xdp_vsi(vsi) || queue_index >= vsi->num_queue_pairs)
+ return;
+
+ i40e_xdp_ring_update_tail(vsi->xdp_rings[queue_index]);
+}
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
index 2444f338bb0c..a97e59721393 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
@@ -510,6 +510,8 @@ u32 i40e_get_tx_pending(struct i40e_ring *ring, bool in_sw);
void i40e_detect_recover_hung(struct i40e_vsi *vsi);
int __i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size);
bool __i40e_chk_linearize(struct sk_buff *skb);
+int i40e_xdp_xmit(struct net_device *dev, struct xdp_buff *xdp);
+void i40e_xdp_flush(struct net_device *dev);
/**
* i40e_get_head - Retrieve head from head writeback
--
2.7.4
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