Hello Andrew, > On 11/17/20 10:18 PM, Gregory Etelson wrote: > > There is a discrepancy between RTE ETHDEV API and flow rules guide > > regarding flow rules maintenance after port stop. RTE ETHDEV API in > > librte_ethdev.h declares that flow rules will not be stored in PMD > > after port stop: > > >>>>> Quite start > > Please note that some configuration is not stored between calls to > > rte_eth_dev_stop()/rte_eth_dev_start(). The following configuration > > will be retained: > > > > - MTU > > - flow control settings > > - receive mode configuration (promiscuous mode, all-multicast mode, > > hardware checksum mode, RSS/VMDQ settings etc.) > > - VLAN filtering configuration > > - default MAC address > > - MAC addresses supplied to MAC address array > > - flow director filtering mode (but not filtering rules) > > - NIC queue statistics mappings > > <<<< Quote end > > > > PMD cannot always correctly restore flow rules after port stop / port > > start because application may alter port configuration after port stop > > without PMD knowledge about undergoing changes. Consider the > > following scenario: > > application configures 2 queues 0 and 1 and creates a flow rule with > > 'queue index 1' action. After that application stops the port and > > removes queue 1. > > Although PMD can implement flow rule shadow copy to be used for > > restore after port start, attempt to restore flow rule from shadow > > will fail in example above and PMD could not notify application about > > that failure. As the result, flow rules map in HW will differ from > > what application expects. In addition, flow rules shadow copy used > > for port start restore consumes considerable amount of system memory, > > especially in systems with millions of flow rules. > > > > Signed-off-by: Gregory Etelson <getel...@nvidia.com> > > Acked-by: Ori Kam <or...@nvidia.com> > > --- > > doc/guides/prog_guide/rte_flow.rst | 5 ++--- > > 1 file changed, 2 insertions(+), 3 deletions(-) > > > > diff --git a/doc/guides/prog_guide/rte_flow.rst > > b/doc/guides/prog_guide/rte_flow.rst > > index 944e8242d6..dfe5a40f8e 100644 > > --- a/doc/guides/prog_guide/rte_flow.rst > > +++ b/doc/guides/prog_guide/rte_flow.rst > > @@ -3055,10 +3055,9 @@ Caveats > > temporarily replacing the burst function pointers), an appropriate > error > > code must be returned (``EBUSY``). > > > > -- PMDs, not applications, are responsible for maintaining flow rules > > +- Applications, not PMDs, are responsible for maintaining flow rules > > configuration when stopping and restarting a port or performing > > other > > - actions which may affect them. They can only be destroyed > > explicitly by > > - applications. > > + actions which may affect them. > > > > For devices exposing multiple ports sharing global settings affected > by flow > > rules: > > > > Re-reading it, it still looks vague. What happens on: > - port stop without removal of flow rule before > - port close without removal of flow rules before > - port reset (which could be stop/start, e.g. to recover from error > condition)
PMD should remove all flows related to hardware resource that was invalidated.
