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Message-ID: <20210118125026.GT3565223@nanopsycho.orion>
Date: Mon, 18 Jan 2021 13:50:26 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Ido Schimmel <idosch@...sch.org>
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
Fri, Jan 15, 2021 at 07:09:44PM CET, idosch@...sch.org wrote:
>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.
Hmm. Still, consider the async nature. Do you have any example of attr
set with async nature? I expect the attr to be set when cmd returns 0.
IDK. Does not feel correct...
>
>>
>>
>> >
>> >> +
>> >> /* 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.
Ok.
>
>>
>>
>> >
>> >> + 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.
Then this check will need to be changed...
>
>>
>>
>> >
>> >> + nla_put_string(msg, DEVLINK_ATTR_LINECARD_TYPE,
>> >> + linecard->provisioned_type))
>> >> + goto nla_put_failure;
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