On 17.04.2025 13:23, Jürgen Groß wrote:
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:
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); }
Juergen
P.S.: please don't use HTML in emails
I can't do this because xennet_xdp_xmit() can return a value > 0