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Date: Fri, 15 Jan 2021 20:09:44 +0200
From: Ido Schimmel <idosch@...sch.org>
To: Jiri Pirko <jiri@...nulli.us>
Cc: netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
jacob.e.keller@...el.com, roopa@...dia.com, mlxsw@...dia.com
Subject: Re: [patch net-next RFC 02/10] devlink: implement line card
provisioning
On Fri, Jan 15, 2021 at 05:51:57PM +0100, Jiri Pirko wrote:
> Fri, Jan 15, 2021 at 05:03:19PM CET, idosch@...sch.org wrote:
> >On Wed, Jan 13, 2021 at 01:12:14PM +0100, Jiri Pirko wrote:
> >> From: Jiri Pirko <jiri@...dia.com>
> >>
> >> In order to be able to configure all needed stuff on a port/netdevice
> >> of a line card without the line card being present, introduce line card
> >> provisioning. Basically provisioning will create a placeholder for
> >> instances (ports/netdevices) for a line card type.
> >>
> >> Allow the user to query the supported line card types over line card
> >> get command. Then implement two netlink commands to allow user to
> >> provision/unprovision the line card with selected line card type.
> >>
> >> On the driver API side, add provision/unprovision ops and supported
> >> types array to be advertised. Upon provision op call, the driver should
> >> take care of creating the instances for the particular line card type.
> >> Introduce provision_set/clear() functions to be called by the driver
> >> once the provisioning/unprovisioning is done on its side.
> >>
> >> Signed-off-by: Jiri Pirko <jiri@...dia.com>
> >> ---
> >> include/net/devlink.h | 31 +++++++-
> >> include/uapi/linux/devlink.h | 17 +++++
> >> net/core/devlink.c | 141 ++++++++++++++++++++++++++++++++++-
> >> 3 files changed, 185 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/include/net/devlink.h b/include/net/devlink.h
> >> index 67c2547d5ef9..854abd53e9ea 100644
> >> --- a/include/net/devlink.h
> >> +++ b/include/net/devlink.h
> >> @@ -139,10 +139,33 @@ struct devlink_port {
> >> struct mutex reporters_lock; /* Protects reporter_list */
> >> };
> >>
> >> +struct devlink_linecard_ops;
> >> +
> >> struct devlink_linecard {
> >> struct list_head list;
> >> struct devlink *devlink;
> >> unsigned int index;
> >> + const struct devlink_linecard_ops *ops;
> >> + void *priv;
> >> + enum devlink_linecard_state state;
> >> + const char *provisioned_type;
> >> +};
> >> +
> >> +/**
> >> + * struct devlink_linecard_ops - Linecard operations
> >> + * @supported_types: array of supported types of linecards
> >> + * @supported_types_count: number of elements in the array above
> >> + * @provision: callback to provision the linecard slot with certain
> >> + * type of linecard
> >> + * @unprovision: callback to unprovision the linecard slot
> >> + */
> >> +struct devlink_linecard_ops {
> >> + const char **supported_types;
> >> + unsigned int supported_types_count;
> >> + int (*provision)(struct devlink_linecard *linecard, void *priv,
> >> + u32 type_index, struct netlink_ext_ack *extack);
> >> + int (*unprovision)(struct devlink_linecard *linecard, void *priv,
> >> + struct netlink_ext_ack *extack);
> >> };
> >>
> >> struct devlink_sb_pool_info {
> >> @@ -1414,9 +1437,13 @@ void devlink_port_attrs_pci_pf_set(struct devlink_port *devlink_port, u32 contro
> >> u16 pf, bool external);
> >> void devlink_port_attrs_pci_vf_set(struct devlink_port *devlink_port, u32 controller,
> >> u16 pf, u16 vf, bool external);
> >> -struct devlink_linecard *devlink_linecard_create(struct devlink *devlink,
> >> - unsigned int linecard_index);
> >> +struct devlink_linecard *
> >> +devlink_linecard_create(struct devlink *devlink, unsigned int linecard_index,
> >> + const struct devlink_linecard_ops *ops, void *priv);
> >> void devlink_linecard_destroy(struct devlink_linecard *linecard);
> >> +void devlink_linecard_provision_set(struct devlink_linecard *linecard,
> >> + u32 type_index);
> >> +void devlink_linecard_provision_clear(struct devlink_linecard *linecard);
> >> int devlink_sb_register(struct devlink *devlink, unsigned int sb_index,
> >> u32 size, u16 ingress_pools_count,
> >> u16 egress_pools_count, u16 ingress_tc_count,
> >> diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
> >> index e5ed0522591f..4111ddcc000b 100644
> >> --- a/include/uapi/linux/devlink.h
> >> +++ b/include/uapi/linux/devlink.h
> >> @@ -131,6 +131,9 @@ enum devlink_command {
> >> DEVLINK_CMD_LINECARD_NEW,
> >> DEVLINK_CMD_LINECARD_DEL,
> >>
> >> + DEVLINK_CMD_LINECARD_PROVISION,
> >> + DEVLINK_CMD_LINECARD_UNPROVISION,
> >
> >I do not really see the point in these two commands. Better extend
> >DEVLINK_CMD_LINECARD_SET to carry these attributes.
>
> Yeah, I was thinking about that. Not sure it is correct though. This is
> single purpose command. It really does not change "an attribute" as the
> "_SET" commands are usually doing. Consider extension of "_SET" by other
> attributes. Then it looks wrong.
It is setting the type of the linecard, which is an attribute of the
linecard.
>
>
> >
> >> +
> >> /* add new commands above here */
> >> __DEVLINK_CMD_MAX,
> >> DEVLINK_CMD_MAX = __DEVLINK_CMD_MAX - 1
> >> @@ -329,6 +332,17 @@ enum devlink_reload_limit {
> >>
> >> #define DEVLINK_RELOAD_LIMITS_VALID_MASK (_BITUL(__DEVLINK_RELOAD_LIMIT_MAX) - 1)
> >>
> >> +enum devlink_linecard_state {
> >> + DEVLINK_LINECARD_STATE_UNSPEC,
> >> + DEVLINK_LINECARD_STATE_UNPROVISIONED,
> >> + DEVLINK_LINECARD_STATE_UNPROVISIONING,
> >> + DEVLINK_LINECARD_STATE_PROVISIONING,
> >
> >Can you explain why these two states are necessary? Any reason the
> >provision operation can't be synchronous? This is somewhat explained in
> >patch #8, but it should really be explained here. Changelog says:
> >
> >"To avoid deadlock and to mimic actual HW flow, use workqueue
> >to add/del ports during provisioning as the port add/del calls
> >devlink_port_register/unregister() which take devlink mutex."
> >
> >The deadlock is not really a reason to have these states.
>
> It is, need to avoid recursice locking
>
> >'DEVLINK_CMD_PORT_SPLIT' also calls devlink_port_register() /
> >devlink_port_unregister() and the deadlock is solved by:
> >
> >'internal_flags = DEVLINK_NL_FLAG_NO_LOCK'
>
> Yeah, however, there, the port_index is passed down to the driver, not
> the actual object pointer. That's why it can be done like that.
>
> >
> >A hardware flow the requires it is something else...
>
> Hardware flow in case of Spectrum is async too.
OK, so the changelog needs to state that these states are necessary
because the nature of linecard provisioning is asynchronous.
>
>
> >
> >> + DEVLINK_LINECARD_STATE_PROVISIONED,
> >> +
> >> + __DEVLINK_LINECARD_STATE_MAX,
> >> + DEVLINK_LINECARD_STATE_MAX = __DEVLINK_LINECARD_STATE_MAX - 1
> >> +};
> >> +
> >> enum devlink_attr {
> >> /* don't change the order or add anything between, this is ABI! */
> >> DEVLINK_ATTR_UNSPEC,
> >> @@ -535,6 +549,9 @@ enum devlink_attr {
> >> DEVLINK_ATTR_RELOAD_ACTION_STATS, /* nested */
> >>
> >> DEVLINK_ATTR_LINECARD_INDEX, /* u32 */
> >> + DEVLINK_ATTR_LINECARD_STATE, /* u8 */
> >> + DEVLINK_ATTR_LINECARD_TYPE, /* string */
> >> + DEVLINK_ATTR_LINECARD_SUPPORTED_TYPES, /* nested */
> >>
> >> /* add new attributes above here, update the policy in devlink.c */
> >>
> >> diff --git a/net/core/devlink.c b/net/core/devlink.c
> >> index 564e921133cf..434eecc310c3 100644
> >> --- a/net/core/devlink.c
> >> +++ b/net/core/devlink.c
> >> @@ -1192,7 +1192,9 @@ static int devlink_nl_linecard_fill(struct sk_buff *msg,
> >> u32 seq, int flags,
> >> struct netlink_ext_ack *extack)
> >> {
> >> + struct nlattr *attr;
> >> void *hdr;
> >> + int i;
> >>
> >> hdr = genlmsg_put(msg, portid, seq, &devlink_nl_family, flags, cmd);
> >> if (!hdr)
> >> @@ -1202,6 +1204,22 @@ static int devlink_nl_linecard_fill(struct sk_buff *msg,
> >> goto nla_put_failure;
> >> if (nla_put_u32(msg, DEVLINK_ATTR_LINECARD_INDEX, linecard->index))
> >> goto nla_put_failure;
> >> + if (nla_put_u8(msg, DEVLINK_ATTR_LINECARD_STATE, linecard->state))
> >> + goto nla_put_failure;
> >> + if (linecard->state >= DEVLINK_LINECARD_STATE_PROVISIONED &&
> >
> >This assumes that every state added after provisioned should report the
> >type. Better to check for the specific states
>
> Yes, that is correct assumption.
It is correct now, but what if tomorrow someone adds a new state? It
can't be added before the provisioned state because it will break uapi.
>
>
> >
> >> + nla_put_string(msg, DEVLINK_ATTR_LINECARD_TYPE,
> >> + linecard->provisioned_type))
> >> + goto nla_put_failure;
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