On Tue, 17 Feb 2026 09:41:07 +0300 Andrew Rybchenko <[email protected]> wrote:
> On 2/16/26 9:00 PM, Stephen Hemminger wrote: > > The documentation for rte_eth_tx_burst() uses the word "sent" to > > describe the return value, which is misleading. Packets returned as > > consumed may not have been transmitted yet; they have been accepted > > by the driver and are no longer the caller's responsibility. > > > > This matters because the common usage pattern is: > > > > n = rte_eth_tx_burst(port, txq, mbufs, nb_pkts); > > for (i = n; i < nb_pkts; i++) > > rte_pktmbuf_free(mbufs[i]); > > > > For this to work correctly, the contract must be: > > - tx_pkts[0..n-1]: ownership transferred to the driver. > > - tx_pkts[n..nb_pkts-1]: untouched, still owned by the caller. > > > > Several drivers (and AI-assisted reviews) misinterpret the current > > wording and treat packets with errors as unconsumed, returning a > > short count. This causes callers to retry those packets indefinitely. > > The correct behavior is that the driver must consume (and free) > > erroneous packets, counting them via tx_errors. > > > > Replace "sent" with "consumed" in the return value description, > > spell out the mbuf ownership contract, clarify the error handling > > expectation, and update the @return block to match. > > > > Signed-off-by: Stephen Hemminger <[email protected]> > > Acked-by: Andrew Rybchenko <[email protected]> > > Thanks for the clarification. I really like it. > I haven't reviewed all drivers but have found bugs related to this in tap, af_packet and likely other software drivers. The hardware drivers seem to be modeled after ixgbe and get it right.
