> >> 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. > > Stop? Close? I agree and documentation should say so in a bit clear way.
I'll post updated document patch.
