From 4467fed6f9abe01e8193eeb9a7be7de69a4fd336 Mon Sep 17 00:00:00 2001 From: Gregory Etelson Date: Wed, 18 Nov 2020 18:15:20 +0200 Subject: [PATCH] doc: update flow API guide for rule removal on stop There is a discrepancy between ethdev API and flow rules guide regarding flow rules maintenance after port stop. librte_ethdev.h declares that flow rules will not be stored in PMD after port stop: >>>>> Quote 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 Acked-by: Ori Kam Acked-by: Ajit Khaparde --- doc/guides/prog_guide/rte_flow.rst | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst index ea203e0ca4..4cff9332fa 100644 --- a/doc/guides/prog_guide/rte_flow.rst +++ b/doc/guides/prog_guide/rte_flow.rst @@ -3229,10 +3229,12 @@ Caveats temporarily replacing the burst function pointers), an appropriate error code must be returned (``EBUSY``). -- PMDs, not applications, 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. +- Applications, not PMDs, are responsible for maintaining flow rules + configuration when closing, stopping or restarting a port or performing other + actions which may affect them. + Applications must assume that after port close, stop or restart all flows + related to that port are not valid, hardware rules are destroyed and relevant + PMD resources are released. For devices exposing multiple ports sharing global settings affected by flow rules: -- 2.20.1