Re: [PATCH net v2] igb: Fix XDP with PTP enabled

Thanks for this work; I was having trouble using XDP on my I354 NIC until this.

Hopefully I have not err'd backporting it to 5.10 -- but I'm seeing
jumbo frames dropped after applying this (though as previously
mentioned, non-skb/full driver XDP programs do now work).

Looking at the code, I'm not sure why that is.

- Tyler

On Sun Apr 25 2021, Tyler S wrote:

Thanks for this work; I was having trouble using XDP on my I354 NIC until this.

Hopefully I have not err'd backporting it to 5.10 -- but I'm seeing
jumbo frames dropped after applying this (though as previously
mentioned, non-skb/full driver XDP programs do now work).

Looking at the code, I'm not sure why that is.

I'm also not sure, yet.

Can you try with version 3 of this patch [1] and see if there are still
issues with jumbo frames? Can you also share the backported patch for
v5.10?

Thanks,
Kurt

[1] - https://lkml.kernel.org/netdev/20210422052617.17267-1-kurt@linutronix.de/

On Mon, Apr 26, 2021 at 10:15 AM Kurt Kanzenbach [off-list ref] wrote:

On Sun Apr 25 2021, Tyler S wrote:

quoted

Thanks for this work; I was having trouble using XDP on my I354 NIC until this.

Hopefully I have not err'd backporting it to 5.10 -- but I'm seeing
jumbo frames dropped after applying this (though as previously
mentioned, non-skb/full driver XDP programs do now work).

Looking at the code, I'm not sure why that is.

I'm also not sure, yet.

Can you try with version 3 of this patch [1] and see if there are still
issues with jumbo frames? Can you also share the backported patch for
v5.10?

Thanks,
Kurt

[1] - https://lkml.kernel.org/netdev/20210422052617.17267-1-kurt@linutronix.de/

Sorry, I didn't see v3.  I can confirm that v3 fixes the issue I was
seeing with jumbo frames.

The only part of the patch that differs for 5.10 is the hunk I'll
include inline.  Thanks again for your work!

Cheers,
Tyler

@@ -8720,11 +8716,22 @@ static int igb_clean_rx_irq(struct

igb_q_vector *q_vector, const int budget)
                dma_rmb();

                rx_buffer = igb_get_rx_buffer(rx_ring, size, &rx_buf_pgcnt);
+               pktbuf = page_address(rx_buffer->page) + rx_buffer->page_offset;
+
+               /* pull rx packet timestamp if available and valid */
+               if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
+                       timestamp = igb_ptp_rx_pktstamp(rx_ring->q_vector,
+                                                       pktbuf);
+
+                       if (timestamp) {
+                               pkt_offset += IGB_TS_HDR_LEN;
+                               size -= IGB_TS_HDR_LEN;
+                       }
+               }

                /* retrieve a buffer from the ring */
                if (!skb) {
-                       xdp.data = page_address(rx_buffer->page) +
-                                  rx_buffer->page_offset;
+                       xdp.data = pktbuf + pkt_offset;
                        xdp.data_meta = xdp.data;
                        xdp.data_hard_start = xdp.data -
                                              igb_rx_offset(rx_ring);

On Tue Apr 27 2021, Tyler S wrote:

Sorry, I didn't see v3.  I can confirm that v3 fixes the issue I was
seeing with jumbo frames.

Great :). I just sent v4 and added you to Cc.

Thanks,
Kurt