On Thu, Feb 06, 2025 at 02:04:07PM +0800, Song Yoong Siang wrote:
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.
Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com
Reviewed-by: Maciej Fijalkowski maciej.fijalkowski@intel.com
with one nit below.
drivers/net/ethernet/intel/igc/igc_main.c | 84 ++++++++++++++--------- 1 file changed, 52 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..3df608601a4b 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -1092,7 +1092,9 @@ 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");
if (net_ratelimit())netdev_err(ring->netdev,"DMA mapping error for empty frame\n");
This is open-coded net_err_ratelimited(), no?
return -ENOMEM;} @@ -1108,20 +1110,12 @@ 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 +1134,6 @@ 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 +1559,41 @@ 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)) {
if (net_ratelimit())netdev_err(tx_ring->netdev,"skb alloc error for empty frame\n");
ditto
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 +1613,7 @@ 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,*/ for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
- otherwise try next time
@@ -1605,24 +1633,16 @@ 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