Re: [patch net-next v3 04/17] net: introduce generic switch devices support

Roopa Prabhu
2014-11-25T16:07:24Z

On 11/25/14, 2:28 AM, Jiri Pirko wrote:
> The goal of this is to provide a possibility to support various switch
> chips. Drivers should implement relevant ndos to do so. Now there is
> only one ndo defined:
> - for getting physical switch id is in place.
>
> Note that user can use random port netdevice to access the switch.
>
> Signed-off-by: Jiri Pirko <jiri@resnulli.us>
> Reviewed-by: Thomas Graf <tgraf@suug.ch>
> ---
> v2->v3:
> -fixed documentation typo pointed out by M. Braun
> -changed "sw" string to "switch" to avoid confusion

Still voting for something generic like "hw" or "offload" or "hw_offload"
> v1->v2:
> -no change
> ---
> Documentation/networking/switchdev.txt | 59 ++++++++++++++++++++++++++++++++++
> MAINTAINERS | 7 ++++
> include/linux/netdevice.h | 10 ++++++
> include/net/switchdev.h | 30 +++++++++++++++++
> net/Kconfig | 1 +
> net/Makefile | 3 ++
> net/switchdev/Kconfig | 13 ++++++++
> net/switchdev/Makefile | 5 +++
> net/switchdev/switchdev.c | 33 +++++++++++++++++++
> 9 files changed, 161 insertions(+)
> create mode 100644 Documentation/networking/switchdev.txt
> create mode 100644 include/net/switchdev.h
> create mode 100644 net/switchdev/Kconfig
> create mode 100644 net/switchdev/Makefile
> create mode 100644 net/switchdev/switchdev.c
>
> diff --git a/Documentation/networking/switchdev.txt b/Documentation/networking/switchdev.txt
> new file mode 100644
> index 0000000..f981a92
> --- /dev/null
> +++ b/Documentation/networking/switchdev.txt
> @@ -0,0 +1,59 @@
> +Switch (and switch-ish) device drivers HOWTO
> +===========================
> +
> +Please note that the word "switch" is here used in very generic meaning.
> +This include devices supporting L2/L3 but also various flow offloading chips,
> +including switches embedded into SR-IOV NICs.
> +
> +Lets describe a topology a bit. Imagine the following example:
> +
> + +----------------------------+ +---------------+
> + | SOME switch chip | | CPU |
> + +----------------------------+ +---------------+
> + port1 port2 port3 port4 MNGMNT | PCI-E |
> + | | | | | +---------------+
> + PHY PHY | | | | NIC0 NIC1
> + | | | | | |
> + | | +- PCI-E -+ | |
> + | +------- MII -------+ |
> + +------------- MII ------------+
> +
> +In this example, there are two independent lines between the switch silicon
> +and CPU. NIC0 and NIC1 drivers are not aware of a switch presence. They are
> +separate from the switch driver. SOME switch chip is by managed by a driver
> +via PCI-E device MNGMNT. Note that MNGMNT device, NIC0 and NIC1 may be
> +connected to some other type of bus.
> +
> +Now, for the previous example show the representation in kernel:
> +
> + +----------------------------+ +---------------+
> + | SOME switch chip | | CPU |
> + +----------------------------+ +---------------+
> + sw0p0 sw0p1 sw0p2 sw0p3 MNGMNT | PCI-E |
> + | | | | | +---------------+
> + PHY PHY | | | | eth0 eth1
> + | | | | | |
> + | | +- PCI-E -+ | |
> + | +------- MII -------+ |
> + +------------- MII ------------+
> +
> +Lets call the example switch driver for SOME switch chip "SOMEswitch". This
> +driver takes care of PCI-E device MNGMNT. There is a netdevice instance sw0pX
> +created for each port of a switch. These netdevices are instances
> +of "SOMEswitch" driver. sw0pX netdevices serve as a "representation"
> +of the switch chip. eth0 and eth1 are instances of some other existing driver.
> +
> +The only difference of the switch-port netdevice from the ordinary netdevice
> +is that is implements couple more NDOs:
> +
> + ndo_switch_parent_id_get - This returns the same ID for two port netdevices
> + of the same physical switch chip. This is
> + mandatory to be implemented by all switch drivers
> + and serves the caller for recognition of a port
> + netdevice.
> + ndo_switch_parent_* - Functions that serve for a manipulation of the switch
> + chip itself (it can be though of as a "parent" of the
> + port, therefore the name). They are not port-specific.
> + Caller might use arbitrary port netdevice of the same
> + switch and it will make no difference.
> + ndo_switch_port_* - Functions that serve for a port-specific manipulation.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a545d68..05addb6 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9058,6 +9058,13 @@ F: lib/swiotlb.c
> F: arch/*/kernel/pci-swiotlb.c
> F: include/linux/swiotlb.h
>
> +SWITCHDEV
> +M: Jiri Pirko <jiri@resnulli.us>
> +L: netdev@vger.kernel.org
> +S: Supported
> +F: net/switchdev/
> +F: include/net/switchdev.h
> +
> SYNOPSYS ARC ARCHITECTURE
> M: Vineet Gupta <vgupta@synopsys.com>
> S: Supported
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 5b491b3..ce096dc 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -1018,6 +1018,12 @@ typedef u16 (*select_queue_fallback_t)(struct net_device *dev,
> * performing GSO on a packet. The device returns true if it is
> * able to GSO the packet, false otherwise. If the return value is
> * false the stack will do software GSO.
> + *
> + * int (*ndo_switch_parent_id_get)(struct net_device *dev,
> + * struct netdev_phys_item_id *psid);
> + * Called to get an ID of the switch chip this port is part of.
> + * If driver implements this, it indicates that it represents a port
> + * of a switch chip.
> */
> struct net_device_ops {
> int (*ndo_init)(struct net_device *dev);
> @@ -1171,6 +1177,10 @@ struct net_device_ops {
> int (*ndo_get_lock_subclass)(struct net_device *dev);
> bool (*ndo_gso_check) (struct sk_buff *skb,
> struct net_device *dev);
> +#ifdef CONFIG_NET_SWITCHDEV
> + int (*ndo_switch_parent_id_get)(struct net_device *dev,
> + struct netdev_phys_item_id *psid);
> +#endif
> };
>
> /**
> diff --git a/include/net/switchdev.h b/include/net/switchdev.h
> new file mode 100644
> index 0000000..7a52360
> --- /dev/null
> +++ b/include/net/switchdev.h
> @@ -0,0 +1,30 @@
> +/*
> + * include/net/switchdev.h - Switch device API
> + * Copyright (c) 2014 Jiri Pirko <jiri@resnulli.us>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +#ifndef _LINUX_SWITCHDEV_H_
> +#define _LINUX_SWITCHDEV_H_
> +
> +#include <linux/netdevice.h>
> +
> +#ifdef CONFIG_NET_SWITCHDEV
> +
> +int netdev_switch_parent_id_get(struct net_device *dev,
> + struct netdev_phys_item_id *psid);
> +
> +#else
> +
> +static inline int netdev_switch_parent_id_get(struct net_device *dev,
> + struct netdev_phys_item_id *psid)
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +#endif
> +
> +#endif /* _LINUX_SWITCHDEV_H_ */
> diff --git a/net/Kconfig b/net/Kconfig
> index 99815b5..ff9ffc1 100644
> --- a/net/Kconfig
> +++ b/net/Kconfig
> @@ -228,6 +228,7 @@ source "net/vmw_vsock/Kconfig"
> source "net/netlink/Kconfig"
> source "net/mpls/Kconfig"
> source "net/hsr/Kconfig"
> +source "net/switchdev/Kconfig"
>
> config RPS
> boolean
> diff --git a/net/Makefile b/net/Makefile
> index 7ed1970..95fc694 100644
> --- a/net/Makefile
> +++ b/net/Makefile
> @@ -73,3 +73,6 @@ obj-$(CONFIG_OPENVSWITCH) += openvswitch/
> obj-$(CONFIG_VSOCKETS) += vmw_vsock/
> obj-$(CONFIG_NET_MPLS_GSO) += mpls/
> obj-$(CONFIG_HSR) += hsr/
> +ifneq ($(CONFIG_NET_SWITCHDEV),)
> +obj-y += switchdev/
> +endif
> diff --git a/net/switchdev/Kconfig b/net/switchdev/Kconfig
> new file mode 100644
> index 0000000..1557545
> --- /dev/null
> +++ b/net/switchdev/Kconfig
> @@ -0,0 +1,13 @@
> +#
> +# Configuration for Switch device support
> +#
> +
> +config NET_SWITCHDEV
> + boolean "Switch (and switch-ish) device support (EXPERIMENTAL)"
> + depends on INET
> + ---help---
> + This module provides glue between core networking code and device
> + drivers in order to support hardware switch chips in very generic
> + meaning of the word "switch". This include devices supporting L2/L3 but
> + also various flow offloading chips, including switches embedded into
> + SR-IOV NICs.
> diff --git a/net/switchdev/Makefile b/net/switchdev/Makefile
> new file mode 100644
> index 0000000..5ed63ed
> --- /dev/null
> +++ b/net/switchdev/Makefile
> @@ -0,0 +1,5 @@
> +#
> +# Makefile for the Switch device API
> +#
> +
> +obj-$(CONFIG_NET_SWITCHDEV) += switchdev.o
> diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
> new file mode 100644
> index 0000000..66973de
> --- /dev/null
> +++ b/net/switchdev/switchdev.c
> @@ -0,0 +1,33 @@
> +/*
> + * net/switchdev/switchdev.c - Switch device API
> + * Copyright (c) 2014 Jiri Pirko <jiri@resnulli.us>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/types.h>
> +#include <linux/init.h>
> +#include <linux/netdevice.h>
> +#include <net/switchdev.h>
> +
> +/**
> + * netdev_switch_parent_id_get - Get ID of a switch
> + * @dev: port device
> + * @psid: switch ID
> + *
> + * Get ID of a switch this port is part of.
> + */
> +int netdev_switch_parent_id_get(struct net_device *dev,
> + struct netdev_phys_item_id *psid)
> +{
> + const struct net_device_ops *ops = dev->netdev_ops;
> +
> + if (!ops->ndo_switch_parent_id_get)
> + return -EOPNOTSUPP;
> + return ops->ndo_switch_parent_id_get(dev, psid);
> +}
> +EXPORT_SYMBOL(netdev_switch_parent_id_get);