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Miller" , Alexei Starovoitov , Andrew Lunn , Daniel Borkmann , Eric Dumazet , Jakub Kicinski , Jesper Dangaard Brouer , John Fastabend , Paolo Abeni , "Kitszel, Przemyslaw" , Stanislav Fomichev , "Nguyen, Anthony L" , "bpf@vger.kernel.org" , "intel-wired-lan@lists.osuosl.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH net v2 1/1] i40e: xsk: advance next_to_clean on status descriptors Message-ID: References: <20251021173200.7908-1-alessandro.d@gmail.com> <20251021173200.7908-2-alessandro.d@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Oct 22, 2025 at 05:41:06AM +0000, Sarkar, Tirthendu wrote: > > From: Jason Xing > > I believe the issue is not that status_descriptor is getting into > multi-buffer packet but not updating next_to_clean results in > I40E_DESC_UNUSED() to return incorrect values. I don't think this is true? next_to_clean can be < next_to_process by design, see if (next_to_process != next_to_clean) first = *i40e_rx_bi(rx_ring, next_to_clean); at the start of i40e_clean_rx_irq_zc. This condition is normal and means when we exited the function - for example because we ran out of budget - we were in the middle of a multi-buffer packet and now we must continue. If I understand the code, I think that in that case we just set entries_to_alloc to a lower number and return fewer buffers to the hardware. > A similar issue was > reported and fixed on the non-ZC path: > https://lore.kernel.org/netdev/20231004083454.20143-1-tirthendu.sarkar@intel.com/ This is indeed exactly the same issue, but I'm not yet sold on the diagnosis :D Ciao, Alessandro