On Wed, 16 Nov 2022 16:51:59 -0500 Luc Pelletier <lucp.at.w...@gmail.com> wrote:
> Hi Konstantin, > > > It is not recommended way to update rte_eth_fp_ops[] contents directly. > > There are eth_dev_fp_ops_setup()/ eth_dev_fp_ops_reset() that supposed > > to be used for that. > > Good to know. I see another fix that was made in a different PMD that > does exactly the same thing: > > https://github.com/DPDK/dpdk/commit/bcd68b68415172815e55fc67cf3947c0433baf74 > > CC'ing the authors for awareness. > > > About the fix itself - while it might help till some extent, > > I think it will not remove the problem completely. > > There still remain a race-condition between rte_eth_rx_burst() and > > failsafe_eth_rmv_event_callback(). > > Right now DPDK doesn't support switching PMD fast-ops functions (or > > updating rxq/txq data) > > on the fly. > > Thanks for the information. This is very helpful. > > Are you saying that the previous code also had that same race > condition? It was only updating the rte_eth_dev structure, but I > assume the problem would have been the same since rte_eth_rx_burst() > in DPDK versions <=20 use the function pointers in rte_eth_dev, not > rte_eth_fp_ops. > > Can you think of a possible solution to this problem? I'm happy to > provide a patch to properly fix the problem. Having your guidance > would be extremely helpful. > > Thanks! Changing burst mode on a running device is not safe because of lack of locking and/or memory barriers. Would have been better to not to do this optimization. Just have one rx_burst/tx_burst function and look at what ever conditions are present there.
