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Make the CC framework more VIMAGE friendly by adding the machinery to allow

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vnets to select their own default CC algorithm independent of each other and the
base system. If the base system or a vnet has set a default which gets unloaded,
we reset that netstack's default to NewReno.

Sponsored by:	FreeBSD Foundation
Tested by:	Mikolaj Golub <to.my.trociny at gmail com>
Reviewed by:	bz (briefly)
MFC after:	3 months
This commit is contained in:
Lawrence Stewart 2010-11-16 09:34:31 +00:00
parent ebf92e869f
commit 78b01840af
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=215395
2 changed files with 34 additions and 32 deletions
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8
sys/netinet/cc.h
View File

@ -58,6 +58,10 @@ extern STAILQ_HEAD(cc_head, cc_algo) cc_list;
extern const int tcprexmtthresh;
extern struct cc_algo newreno_cc_algo;
/* Per-netstack bits. */
VNET_DECLARE(struct cc_algo *, default_cc_ptr);
#define V_default_cc_ptr VNET(default_cc_ptr)
/* Define the new net.inet.tcp.cc sysctl tree. */
SYSCTL_DECL(_net_inet_tcp_cc);
@ -146,7 +150,7 @@ struct cc_algo {
#define CC_DATA(tp) ((tp)->ccv->cc_data)
/* Macro to obtain the system default CC algo's struct ptr. */
#define CC_DEFAULT() STAILQ_FIRST(&cc_list)
#define CC_DEFAULT() V_default_cc_ptr
extern struct rwlock cc_list_lock;
#define CC_LIST_LOCK_INIT() rw_init(&cc_list_lock, "cc_list")
@ -155,6 +159,6 @@ extern struct rwlock cc_list_lock;
#define CC_LIST_RUNLOCK() rw_runlock(&cc_list_lock)
#define CC_LIST_WLOCK() rw_wlock(&cc_list_lock)
#define CC_LIST_WUNLOCK() rw_wunlock(&cc_list_lock)
#define CC_LIST_WLOCK_ASSERT() rw_assert(&cc_list_lock, RA_WLOCKED)
#define CC_LIST_LOCK_ASSERT() rw_assert(&cc_list_lock, RA_LOCKED)
#endif /* _NETINET_CC_H_ */

58
sys/netinet/cc/cc.c
View File

@ -81,24 +81,7 @@ struct cc_head cc_list = STAILQ_HEAD_INITIALIZER(cc_list);
/* Protects the cc_list TAILQ. */
struct rwlock cc_list_lock;
/*
* Set the default CC algorithm to new_default. The default is identified
* by being the first element in the cc_list TAILQ.
*/
static void
cc_set_default(struct cc_algo *new_default)
{
CC_LIST_WLOCK_ASSERT();
/*
* Make the requested system default CC algorithm the first element in
* the list if it isn't already.
*/
if (new_default != CC_DEFAULT()) {
STAILQ_REMOVE(&cc_list, new_default, cc_algo, entries);
STAILQ_INSERT_HEAD(&cc_list, new_default, entries);
}
}
VNET_DEFINE(struct cc_algo *, default_cc_ptr) = &newreno_cc_algo;
/*
* Sysctl handler to show and change the default CC algorithm.
@ -120,15 +103,15 @@ cc_default_algo(SYSCTL_HANDLER_ARGS)
err = sysctl_handle_string(oidp, default_cc, 1, req);
} else {
/* Find algo with specified name and set it to default. */
CC_LIST_WLOCK();
CC_LIST_RLOCK();
STAILQ_FOREACH(funcs, &cc_list, entries) {
if (strncmp((char *)req->newptr, funcs->name,
TCP_CA_NAME_MAX) == 0) {
found = 1;
cc_set_default(funcs);
V_default_cc_ptr = funcs;
}
}
CC_LIST_WUNLOCK();
CC_LIST_RUNLOCK();
if (!found)
err = ESRCH;
@ -172,6 +155,28 @@ cc_list_available(SYSCTL_HANDLER_ARGS)
return (err);
}
/*
* Reset the default CC algo to NewReno for any netstack which is using the algo
* that is about to go away as its default.
*/
static void
cc_checkreset_default(struct cc_algo *remove_cc)
{
VNET_ITERATOR_DECL(vnet_iter);
CC_LIST_LOCK_ASSERT();
VNET_LIST_RLOCK_NOSLEEP();
VNET_FOREACH(vnet_iter) {
CURVNET_SET(vnet_iter);
if (strncmp(CC_DEFAULT()->name, remove_cc->name,
TCP_CA_NAME_MAX) == 0)
V_default_cc_ptr = &newreno_cc_algo;
CURVNET_RESTORE();
}
VNET_LIST_RUNLOCK_NOSLEEP();
}
/*
* Initialise CC subsystem on system boot.
*/
@ -201,14 +206,7 @@ cc_deregister_algo(struct cc_algo *remove_cc)
CC_LIST_WLOCK();
STAILQ_FOREACH_SAFE(funcs, &cc_list, entries, tmpfuncs) {
if (funcs == remove_cc) {
/*
* If we're removing the current system default,
* reset the default to newreno.
*/
if (strncmp(CC_DEFAULT()->name, remove_cc->name,
TCP_CA_NAME_MAX) == 0)
cc_set_default(&newreno_cc_algo);
cc_checkreset_default(remove_cc);
STAILQ_REMOVE(&cc_list, funcs, cc_algo, entries);
err = 0;
break;
@ -302,7 +300,7 @@ SYSINIT(cc, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_FIRST, cc_init, NULL);
SYSCTL_NODE(_net_inet_tcp, OID_AUTO, cc, CTLFLAG_RW, NULL,
"congestion control related settings");
SYSCTL_PROC(_net_inet_tcp_cc, OID_AUTO, algorithm, CTLTYPE_STRING|CTLFLAG_RW,
SYSCTL_VNET_PROC(_net_inet_tcp_cc, OID_AUTO, algorithm, CTLTYPE_STRING|CTLFLAG_RW,
NULL, 0, cc_default_algo, "A", "default congestion control algorithm");
SYSCTL_PROC(_net_inet_tcp_cc, OID_AUTO, available, CTLTYPE_STRING|CTLFLAG_RD,