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net: sctp: refactor active path selection
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This patch just refactors and moves the code for the active
path selection into its own helper function outside of
sctp_assoc_control_transport() which is already big enough.
No functional changes here.

Signed-off-by: Daniel Borkmann <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@davem330
Daniel Borkmann authored and davem330 committed Jun 11, 2014
1 parent 67cb936 commit b82e8f3
Showing 1 changed file with 61 additions and 59 deletions.
120 changes: 61 additions & 59 deletions net/sctp/associola.c
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,7 @@
#include <net/sctp/sm.h>

/* Forward declarations for internal functions. */
static void sctp_select_active_and_retran_path(struct sctp_association *asoc);
static void sctp_assoc_bh_rcv(struct work_struct *work);
static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc);
static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc);
Expand Down Expand Up @@ -774,9 +775,6 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
sctp_transport_cmd_t command,
sctp_sn_error_t error)
{
struct sctp_transport *t = NULL;
struct sctp_transport *first;
struct sctp_transport *second;
struct sctp_ulpevent *event;
struct sockaddr_storage addr;
int spc_state = 0;
Expand Down Expand Up @@ -829,74 +827,22 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
return;
}

/* Generate and send a SCTP_PEER_ADDR_CHANGE notification to the
* user.
/* Generate and send a SCTP_PEER_ADDR_CHANGE notification
* to the user.
*/
if (ulp_notify) {
memset(&addr, 0, sizeof(struct sockaddr_storage));
memcpy(&addr, &transport->ipaddr,
transport->af_specific->sockaddr_len);

event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
0, spc_state, error, GFP_ATOMIC);
if (event)
sctp_ulpq_tail_event(&asoc->ulpq, event);
}

/* Select new active and retran paths. */

/* Look for the two most recently used active transports.
*
* This code produces the wrong ordering whenever jiffies
* rolls over, but we still get usable transports, so we don't
* worry about it.
*/
first = NULL; second = NULL;

list_for_each_entry(t, &asoc->peer.transport_addr_list,
transports) {

if ((t->state == SCTP_INACTIVE) ||
(t->state == SCTP_UNCONFIRMED) ||
(t->state == SCTP_PF))
continue;
if (!first || t->last_time_heard > first->last_time_heard) {
second = first;
first = t;
} else if (!second ||
t->last_time_heard > second->last_time_heard)
second = t;
}

/* RFC 2960 6.4 Multi-Homed SCTP Endpoints
*
* By default, an endpoint should always transmit to the
* primary path, unless the SCTP user explicitly specifies the
* destination transport address (and possibly source
* transport address) to use.
*
* [If the primary is active but not most recent, bump the most
* recently used transport.]
*/
if (((asoc->peer.primary_path->state == SCTP_ACTIVE) ||
(asoc->peer.primary_path->state == SCTP_UNKNOWN)) &&
first != asoc->peer.primary_path) {
second = first;
first = asoc->peer.primary_path;
}

if (!second)
second = first;
/* If we failed to find a usable transport, just camp on the
* primary, even if it is inactive.
*/
if (!first) {
first = asoc->peer.primary_path;
second = asoc->peer.primary_path;
}

/* Set the active and retran transports. */
asoc->peer.active_path = first;
asoc->peer.retran_path = second;
sctp_select_active_and_retran_path(asoc);
}

/* Hold a reference to an association. */
Expand Down Expand Up @@ -1325,6 +1271,62 @@ void sctp_assoc_update_retran_path(struct sctp_association *asoc)
__func__, asoc, &asoc->peer.retran_path->ipaddr.sa);
}

static void sctp_select_active_and_retran_path(struct sctp_association *asoc)
{
struct sctp_transport *trans, *trans_pri = NULL, *trans_sec = NULL;

/* Look for the two most recently used active transports. */
list_for_each_entry(trans, &asoc->peer.transport_addr_list,
transports) {
if (trans->state == SCTP_INACTIVE ||
trans->state == SCTP_UNCONFIRMED ||
trans->state == SCTP_PF)
continue;
if (trans_pri == NULL ||
trans->last_time_heard > trans_pri->last_time_heard) {
trans_sec = trans_pri;
trans_pri = trans;
} else if (trans_sec == NULL ||
trans->last_time_heard > trans_sec->last_time_heard) {
trans_sec = trans;
}
}

/* RFC 2960 6.4 Multi-Homed SCTP Endpoints
*
* By default, an endpoint should always transmit to the primary
* path, unless the SCTP user explicitly specifies the
* destination transport address (and possibly source transport
* address) to use. [If the primary is active but not most recent,
* bump the most recently used transport.]
*/
if ((asoc->peer.primary_path->state == SCTP_ACTIVE ||
asoc->peer.primary_path->state == SCTP_UNKNOWN) &&
asoc->peer.primary_path != trans_pri) {
trans_sec = trans_pri;
trans_pri = asoc->peer.primary_path;
}

/* We did not find anything useful for a possible retransmission
* path; either primary path that we found is the the same as
* the current one, or we didn't generally find an active one.
*/
if (trans_sec == NULL)
trans_sec = trans_pri;

/* If we failed to find a usable transport, just camp on the
* primary, even if they are inactive.
*/
if (trans_pri == NULL) {
trans_pri = asoc->peer.primary_path;
trans_sec = asoc->peer.primary_path;
}

/* Set the active and retran transports. */
asoc->peer.active_path = trans_pri;
asoc->peer.retran_path = trans_sec;
}

struct sctp_transport *
sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
struct sctp_transport *last_sent_to)
Expand Down

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