Collaboration diagram for Queueing Disciplines:

Modules
	Queueing Discipline Modules

	Queueing Discipline Object

Data Structures
struct	rtnl_qdisc_ops
	Qdisc Operations. More...

QDisc Addition
int	rtnl_qdisc_build_add_request (struct rtnl_qdisc qdisc, int flags, struct nl_msg *result)
	Build a netlink message to add a new qdisc. More...

int	rtnl_qdisc_add (struct nl_sock sk, struct rtnl_qdisc qdisc, int flags)
	Add a new qdisc. More...

QDisc Modification
int	rtnl_qdisc_build_change_request (struct rtnl_qdisc qdisc, struct rtnl_qdisc new, struct nl_msg **result)
	Build a netlink message to change attributes of a existing qdisc. More...

int	rtnl_qdisc_change (struct nl_sock sk, struct rtnl_qdisc qdisc, struct rtnl_qdisc *new)
	Change attributes of a qdisc. More...

QDisc Deletion
int	rtnl_qdisc_build_delete_request (struct rtnl_qdisc qdisc, struct nl_msg *result)
	Build a netlink request message to delete a qdisc. More...

int	rtnl_qdisc_delete (struct nl_sock sk, struct rtnl_qdisc qdisc)
	Delete a qdisc. More...

Qdisc Cache Management
int	rtnl_qdisc_alloc_cache (struct nl_sock sk, struct nl_cache *result)
	Build a qdisc cache including all qdiscs currently configured in the kernel. More...

struct rtnl_qdisc *	rtnl_qdisc_get_by_parent (struct nl_cache *cache, int ifindex, uint32_t parent)
	Look up qdisc by its parent in the provided cache. More...

struct rtnl_qdisc *	rtnl_qdisc_get (struct nl_cache *cache, int ifindex, uint32_t handle)
	Look up qdisc by its handle in the provided cache. More...

Detailed Description

Qdisc Handles

In general, qdiscs are identified by the major part of a traffic control handle (the upper 16 bits). A few special values exist though:

TC_H_ROOT: root qdisc (directly attached to the device)
TC_H_INGRESS: ingress qdisc (directly attached to the device)
TC_H_UNSPEC: unspecified qdisc (no reference)

1) Adding a Qdisc: // Allocate a new empty qdisc to be filled out

struct rtnl_qdisc *qdisc = rtnl_qdisc_alloc();

// ... specify the kind of the Qdisc

rtnl_qdisc_set_kind(qdisc, "pfifo");

// Specify the device the qdisc should be attached to

rtnl_qdisc_set_ifindex(qdisc, ifindex);

// ... specify the parent qdisc

rtnl_qdisc_set_parent(qdisc, TC_H_ROOT);

// Specifying the handle is not required but makes reidentifying easier

// and may help to avoid adding a qdisc twice.

rtnl_qdisc_set_handle(qdisc, 0x000A0000);

// Now on to specify the qdisc specific options, see the relevant qdisc

// modules for documentation, in this example we set the upper limit of

// the packet fifo qdisc to 64

rtnl_qdisc_fifo_set_limit(qdisc, 64);

rtnl_qdisc_add(handle, qdisc, NLM_R_REPLACE);

// Free up the memory

rtnl_qdisc_put(qdisc);

2) Deleting a Qdisc: // Allocate a new empty qdisc to be filled out with the parameters

// specifying the qdisc to be deleted. Alternatively a fully equiped

// Qdisc object from a cache can be used.

struct rtnl_qdisc *qdisc = rtnl_qdisc_alloc();

// The interface index of the device the qdisc is on and the parent handle

// are the least required fields to be filled out.

// Note: Specify TC_H_ROOT or TC_H_INGRESS as parent handle to delete the

// root respectively root ingress qdisc.

rtnl_qdisc_set_ifindex(qdisc, ifindex);

rtnl_qdisc_set_parent(qdisc, parent_handle);

// If required for identification, the handle can be specified as well.

rtnl_qdisc_set_handle(qdisc, qdisc_handle);

// Not required but maybe helpful as sanity check, the kind of the qdisc

// can be specified to avoid mistakes.

rtnl_qdisc_set_kind(qdisc, "pfifo");

// Finally delete the qdisc with rtnl_qdisc_delete(), alternatively

// rtnl_qdisc_build_delete_request() can be invoked to generate an

// appropritate netlink message to send out.

rtnl_qdisc_delete(handle, qdisc);

// Free up the memory

rtnl_qdisc_put(qdisc);

Function Documentation

int rtnl_qdisc_add	(	struct nl_sock *	sk,
		struct rtnl_qdisc *	qdisc,
		int	flags
	)

Add a new qdisc.

sk Netlink socket.
qdisc qdisc to delete
flags additional netlink message flags

Builds a netlink message by calling rtnl_qdisc_build_add_request(), sends the request to the kernel and waits for the ACK to be received and thus blocks until the request has been processed.

Common message flags used:

NLM_F_REPLACE - replace a potential existing qdisc

Returns: 0 on success or a negative error code

References nl_send_auto_complete(), nlmsg_free(), and rtnl_qdisc_build_add_request().

Referenced by main().

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int rtnl_qdisc_alloc_cache	(	struct nl_sock *	sk,
		struct nl_cache **	result
	)

Build a qdisc cache including all qdiscs currently configured in the kernel.

sk Netlink socket.
result Pointer to store resulting message.

Allocates a new cache, initializes it properly and updates it to include all qdiscs currently configured in the kernel.

Returns: 0 on success or a negative error code.

References nl_cache_alloc_and_fill().

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int rtnl_qdisc_build_add_request	(	struct rtnl_qdisc *	qdisc,
		int	flags,
		struct nl_msg **	result
	)

Build a netlink message to add a new qdisc.

qdisc qdisc to add
flags additional netlink message flags
result Pointer to store resulting message.

Builds a new netlink message requesting an addition of a qdisc. The netlink message header isn't fully equipped with all relevant fields and must be sent out via nl_send_auto_complete() or supplemented as needed.

Common message flags used:

NLM_F_REPLACE - replace a potential existing qdisc

Returns: 0 on success or a negative error code.

References NLM_F_CREATE, and RTM_NEWQDISC.

Referenced by rtnl_qdisc_add().

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int rtnl_qdisc_build_change_request	(	struct rtnl_qdisc *	qdisc,
		struct rtnl_qdisc *	new,
		struct nl_msg **	result
	)

Build a netlink message to change attributes of a existing qdisc.

qdisc qdisc to change
new new qdisc attributes
result Pointer to store resulting message.

Builds a new netlink message requesting an change of qdisc attributes. The netlink message header isn't fully equipped with all relevant fields and must be sent out via nl_send_auto_complete() or supplemented as needed.

Returns: 0 on success or a negative error code.

References NLM_F_REPLACE, and RTM_NEWQDISC.

Referenced by rtnl_qdisc_change().

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int rtnl_qdisc_build_delete_request	(	struct rtnl_qdisc *	qdisc,
		struct nl_msg **	result
	)

Build a netlink request message to delete a qdisc.

qdisc qdisc to delete
result Pointer to store resulting message.

Builds a new netlink message requesting a deletion of a qdisc. The netlink message header isn't fully equipped with all relevant fields and must thus be sent out via nl_send_auto_complete() or supplemented as needed.

Returns: 0 on success or a negative error code.

References BUG, NLE_MSGSIZE, NLE_NOMEM, NLMSG_ALIGNTO, nlmsg_alloc_simple(), nlmsg_append(), nlmsg_free(), RTM_DELQDISC, TCA_ATTR_IFINDEX, TCA_ATTR_PARENT, tcmsg::tcm_family, tcmsg::tcm_handle, tcmsg::tcm_ifindex, and tcmsg::tcm_parent.

Referenced by rtnl_qdisc_delete().

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int rtnl_qdisc_change	(	struct nl_sock *	sk,
		struct rtnl_qdisc *	qdisc,
		struct rtnl_qdisc *	new
	)

Change attributes of a qdisc.

sk Netlink socket.
qdisc qdisc to change
new new qdisc attributes

Builds a netlink message by calling rtnl_qdisc_build_change_request(), sends the request to the kernel and waits for the ACK to be received and thus blocks until the request has been processed.

Returns: 0 on success or a negative error code

References nl_send_auto_complete(), nlmsg_free(), and rtnl_qdisc_build_change_request().

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int rtnl_qdisc_delete	(	struct nl_sock *	sk,
		struct rtnl_qdisc *	qdisc
	)

Delete a qdisc.

sk Netlink socket.
qdisc qdisc to delete

Builds a netlink message by calling rtnl_qdisc_build_delete_request(), sends the request to the kernel and waits for the ACK to be received and thus blocks until the request has been processed.

Returns: 0 on success or a negative error code

References nl_send_auto_complete(), nlmsg_free(), and rtnl_qdisc_build_delete_request().

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struct rtnl_qdisc* rtnl_qdisc_get	(	struct nl_cache *	cache,
		int	ifindex,
		uint32_t	handle
	)

Look up qdisc by its handle in the provided cache.

cache qdisc cache
ifindex interface the qdisc is attached to
handle qdisc handle
Returns
pointer to qdisc inside the cache or NULL if no match was found.

References nl_cache::c_items, nl_cache::c_ops, nl_list_for_each_entry, nl_object_get(), and NULL.

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struct rtnl_qdisc* rtnl_qdisc_get_by_parent	(	struct nl_cache *	cache,
		int	ifindex,
		uint32_t	parent
	)

Look up qdisc by its parent in the provided cache.

cache qdisc cache
ifindex interface the qdisc is attached to
parent parent handle
Returns
pointer to qdisc inside the cache or NULL if no match was found.

References nl_cache::c_items, nl_cache::c_ops, nl_list_for_each_entry, nl_object_get(), and NULL.

Referenced by rtnl_class_leaf_qdisc().

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Modules

Data Structures

QDisc Addition

QDisc Modification

QDisc Deletion

Qdisc Cache Management

Detailed Description

Function Documentation