Refactor the code for inserting an empty frame into a new function
igc_insert_empty_frame(). This change extracts the logic for inserting
an empty packet from igc_xmit_frame_ring() into a separate function,
allowing it to be reused in future implementations, such as the XDP
zero copy transmit function.
Remove the igc_desc_unused() checking in igc_init_tx_empty_descriptor()
because the number of descriptors needed is guaranteed.
Ensure that skb allocation and DMA mapping work for the empty frame,
before proceeding to fill in igc_tx_buffer info, context descriptor,
and data descriptor.
Rate limit the error messages for skb allocation and DMA mapping failures.
Update the comment to indicate that the 2 descriptors needed by the empty
frame are already taken into consideration in igc_xmit_frame_ring().
Handle the case where the insertion of an empty frame fails and explain
the reason behind this handling.
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
Signed-off-by: Song Yoong Siang <yoong.siang.song@xxxxxxxxx>
---
drivers/net/ethernet/intel/igc/igc_main.c | 82 ++++++++++++++---------
1 file changed, 50 insertions(+), 32 deletions(-)
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 84307bb7313e..1bfa71545e37 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -1092,7 +1092,8 @@ static int igc_init_empty_frame(struct igc_ring *ring,
dma = dma_map_single(ring->dev, skb->data, size, DMA_TO_DEVICE);
if (dma_mapping_error(ring->dev, dma)) {
- netdev_err_once(ring->netdev, "Failed to map DMA for TX\n");
+ net_err_ratelimited("%s: DMA mapping error for empty frame\n",
+ netdev_name(ring->netdev));
return -ENOMEM;
}
@@ -1108,20 +1109,12 @@ static int igc_init_empty_frame(struct igc_ring *ring,
return 0;
}
-static int igc_init_tx_empty_descriptor(struct igc_ring *ring,
- struct sk_buff *skb,
- struct igc_tx_buffer *first)
+static void igc_init_tx_empty_descriptor(struct igc_ring *ring,
+ struct sk_buff *skb,
+ struct igc_tx_buffer *first)
{
union igc_adv_tx_desc *desc;
u32 cmd_type, olinfo_status;
- int err;
-
- if (!igc_desc_unused(ring))
- return -EBUSY;
-
- err = igc_init_empty_frame(ring, first, skb);
- if (err)
- return err;
cmd_type = IGC_ADVTXD_DTYP_DATA | IGC_ADVTXD_DCMD_DEXT |
IGC_ADVTXD_DCMD_IFCS | IGC_TXD_DCMD |
@@ -1140,8 +1133,6 @@ static int igc_init_tx_empty_descriptor(struct igc_ring *ring,
ring->next_to_use++;
if (ring->next_to_use == ring->count)
ring->next_to_use = 0;
-
- return 0;
}
#define IGC_EMPTY_FRAME_SIZE 60
@@ -1567,6 +1558,40 @@ static bool igc_request_tx_tstamp(struct igc_adapter *adapter, struct sk_buff *s
return false;
}
+static int igc_insert_empty_frame(struct igc_ring *tx_ring)
+{
+ struct igc_tx_buffer *empty_info;
+ struct sk_buff *empty_skb;
+ void *data;
+ int ret;
+
+ empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
+ empty_skb = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);
+ if (unlikely(!empty_skb)) {
+ net_err_ratelimited("%s: skb alloc error for empty frame\n",
+ netdev_name(tx_ring->netdev));
+ return -ENOMEM;
+ }
+
+ data = skb_put(empty_skb, IGC_EMPTY_FRAME_SIZE);
+ memset(data, 0, IGC_EMPTY_FRAME_SIZE);
+
+ /* Prepare DMA mapping and Tx buffer information */
+ ret = igc_init_empty_frame(tx_ring, empty_info, empty_skb);
+ if (unlikely(ret)) {
+ dev_kfree_skb_any(empty_skb);
+ return ret;
+ }
+
+ /* Prepare advanced context descriptor for empty packet */
+ igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);
+
+ /* Prepare advanced data descriptor for empty packet */
+ igc_init_tx_empty_descriptor(tx_ring, empty_skb, empty_info);
+
+ return 0;
+}
+
static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
struct igc_ring *tx_ring)
{
@@ -1586,6 +1611,7 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
* + 1 desc for skb_headlen/IGC_MAX_DATA_PER_TXD,
* + 2 desc gap to keep tail from touching head,
* + 1 desc for context descriptor,
+ * + 2 desc for inserting an empty packet for launch time,
* otherwise try next time
*/
for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
@@ -1605,24 +1631,16 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
launch_time = igc_tx_launchtime(tx_ring, txtime, &first_flag, &insert_empty);
if (insert_empty) {
- struct igc_tx_buffer *empty_info;
- struct sk_buff *empty;
- void *data;
-
- empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
- empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);
- if (!empty)
- goto done;
-
- data = skb_put(empty, IGC_EMPTY_FRAME_SIZE);
- memset(data, 0, IGC_EMPTY_FRAME_SIZE);
-
- igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);
-
- if (igc_init_tx_empty_descriptor(tx_ring,
- empty,
- empty_info) < 0)
- dev_kfree_skb_any(empty);
+ /* Reset the launch time if the required empty frame fails to
+ * be inserted. However, this packet is not dropped, so it
+ * "dirties" the current Qbv cycle. This ensures that the
+ * upcoming packet, which is scheduled in the next Qbv cycle,
+ * does not require an empty frame. This way, the launch time
+ * continues to function correctly despite the current failure
+ * to insert the empty frame.
+ */
+ if (igc_insert_empty_frame(tx_ring))
+ launch_time = 0;
}
done:
--
2.34.1
