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igc: Refactor empty frame insertion for launch time support

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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>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://patch.msgid.link/20250216093430.957880-5-yoong.siang.song@intel.com
This commit is contained in:
Song Yoong Siang
2025-02-16 17:34:29 +08:00
committed by Martin KaFai Lau
parent 04f64dea13
commit f9b53bb139
1 changed files with 50 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/net/ethernet/intel/igc/igc_main.c
+50 -32
View File
@@ -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: