On 17.04.25 12:06, Alexey wrote:
On 17.04.2025 11:51, Juergen Gross wrote:
On 17.04.25 10:45, Alexey wrote:
On 17.04.2025 10:12, Jürgen Groß wrote:
On 17.04.25 09:00, Alexey wrote:
On 17.04.2025 03:58, Jakub Kicinski wrote:
On Mon, 14 Apr 2025 18:34:01 +0000 Alexey Nepomnyashih wrote: > get_page(pdata); Please notice this get_page() here.
> xdpf = xdp_convert_buff_to_frame(xdp); > + if (unlikely(!xdpf)) { > + trace_xdp_exception(queue->info->netdev, prog, act); > + break; > + }
Do you mean that it would be better to move the get_page(pdata) call lower, after checking for NULL in xdpf, so that the reference count is only increased after a successful conversion?
I think the error handling here is generally broken (or at least very questionable).
I suspect that in case of at least some errors the get_page() is leaking even without this new patch.
In case I'm wrong a comment reasoning why there is no leak should be added.
Juergen
I think pdata is freed in xdp_return_frame_rx_napi() -> __xdp_return()
Agreed. But what if xennet_xdp_xmit() returns an error < 0?
In this case xdp_return_frame_rx_napi() won't be called.
Juergen
Agreed. There is no explicit freed pdata in the calling function xennet_get_responses(). Without this, the page referenced by pdata could be leaked.
I suggest:
case XDP_TX:
get_page(pdata);
if (unlikely(!xdpf)) {trace_xdp_exception(queue->info->netdev, prog, act);break;}get_page(pdata);
else if (unlikely(err < 0))
else if (unlikely(err < 0)) { trace_xdp_exception(queue->info->netdev, prog, act);xdp_return_frame_rx_napi(xdpf);}
Could you please merge the two if () blocks, as they share the call of xdp_return_frame_rx_napi() now? Something like:
if (unlikely(err <= 0)) { if (err < 0) trace_xdp_exception(queue->info->netdev, prog, act); xdp_return_frame_rx_napi(xdpf); }
break;case XDP_REDIRECT: get_page(pdata); err = xdp_do_redirect(queue->info->netdev, xdp, prog); *need_xdp_flush = true;
if (unlikely(err))
if (unlikely(err)) { trace_xdp_exception(queue->info->netdev, prog, act);__xdp_return(page_address(pdata), &xdp->mem, true, xdp);}
Juergen
P.S.: please don't use HTML in emails