| Message ID | 20250206060408.808325-5-yoong.siang.song@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | xsk: TX metadata Launch Time support | expand |
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, > * otherwise try next time > */ > for (f = 0; f < skb_shinfo(skb)->nr_frags; f++) > @@ -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 >
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"); 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"); + 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, * otherwise try next time */ for (f = 0; f < skb_shinfo(skb)->nr_frags; f++) @@ -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:
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> --- drivers/net/ethernet/intel/igc/igc_main.c | 84 ++++++++++++++--------- 1 file changed, 52 insertions(+), 32 deletions(-)