Re: [PATCH net] bnxt: properly flush XDP redirect lists

[Michael Chan]

On Mon, Jun 23, 2025 at 10:59 PM Jesper Dangaard Brouer <hawk@xxxxxxxxxx> wrote:
>
> On 23/06/2025 18.06, Yan Zhai wrote:
> > We encountered following crash when testing a XDP_REDIRECT feature
> > in production:
> >
> [...]
> >
> (To Andy + Michael:)
> The initial bug was introduced in [1] commit a7559bc8c17c ("bnxt:
> support transmit and free of aggregation buffers") in bnxt_rx_xdp()
> where case XDP_TX zeros the *event, that also carries the XDP-redirect
> indication.
> I'm wondering if the driver should not reset the *event value?
> (all other drive code paths doesn't)

Resetting *event was only correct before XDP_REDIRECT support was added.

>
>
> > We can stably reproduce this crash by returning XDP_TX
> > and XDP_REDIRECT randomly for incoming packets in a naive XDP program.
> > Properly propagate the XDP_REDIRECT events back fixes the crash.

Thanks for the patch.  The fix is similar to edc0140cc3b7 ("bnxt_en:
Flush XDP for bnxt_poll_nitroa0()'s NAPI")

Somehow the fix was only applied to one chip's poll function and not
the other chips' poll functions.
Reviewed-by: Michael Chan <michael.chan@xxxxxxxxxxxx>

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