Hi Jakub,
On 9/4/2025 6:18 AM, Jakub Kicinski wrote:
On Mon, 1 Sep 2025 15:32:22 +0530 Meghana Malladi wrote:
if (!emac->xdpi.prog && !prog)
return 0;
- WRITE_ONCE(emac->xdp_prog, prog);
+ if (netif_running(emac->ndev)) {
+ prueth_destroy_txq(emac);
+ prueth_destroy_rxq(emac);
+ }
+
+ old_prog = xchg(&emac->xdp_prog, prog);
+ if (old_prog)
+ bpf_prog_put(old_prog);
+
+ if (netif_running(emac->ndev)) {
+ ret = prueth_create_rxq(emac);
shutting the device down and freeing all rx memory for reconfig is not
okay. If the system is low on memory the Rx buffer allocations may fail
and system may drop off the network. You must either pre-allocate or
avoid freeing the memory, and just restart the queues.
So I have been working on trying to address this comment and maintain
parity with the existing support provided by this series but looks like
I might be missing something which is causing some regressions.
I am facing an issue with zero copy Rx, where there is some active
traffic being received by the DUT (running in copy mode - default state)
and I switch to zero copy mode using AF-XDP_example [1], I am not able
to receive any packets because I observe that the napi_rx_poll is not
getting scheduled for whatever reason, ending up draining the rx
descriptors and leading to memory leak. But if I first switch from copy
to zero copy mode and then try sending traffic I am able to receive
traffic on long runs without any failure or crash. I am not able to
figure out why is this happening, so sharing my changes [2] on top of
this series, which I made to address your comment. I am wondering if you
could have a look and give me some pointers here. Thank you.
[1] https://github.com/xdp-project/bpf-examples/tree/main/AF_XDP-example
[2]
https://gist.github.com/MeghanaMalladiTI/4c1cb106aee5bef4489ab372938d62d9
+ if (ret) {
+ netdev_err(emac->ndev, "Failed to create RX queue:
%d\n", ret);
+ return ret;
+ }
+
+ ret = prueth_create_txq(emac);
+ if (ret) {
+ netdev_err(emac->ndev, "Failed to create TX queue:
%d\n", ret);
+ prueth_destroy_rxq(emac);
+ emac->xdp_prog = NULL;
+ return ret;
+ }
+ }
xdp_attachment_setup(&emac->xdpi, bpf);
--
Thanks,
Meghana Malladi
