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Move protocol specific implementation detail out of the core CC framework.

Browse Source 
Sponsored by:	FreeBSD Foundation
Tested by:	Mikolaj Golub <to.my.trociny at gmail com>
MFC after:	11 weeks
X-MFC with:	r215166
This commit is contained in:
Lawrence Stewart 2010-11-16 08:30:39 +00:00
parent 4e805854ed
commit 99065ae6a8
3 changed files with 70 additions and 48 deletions
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54
sys/netinet/cc/cc.c
View File

@ -190,10 +190,7 @@ int
cc_deregister_algo(struct cc_algo *remove_cc)
{
struct cc_algo *funcs, *tmpfuncs;
struct tcpcb *tp;
struct inpcb *inp;
int err;
VNET_ITERATOR_DECL(vnet_iter);
err = ENOENT;
@ -220,53 +217,14 @@ cc_deregister_algo(struct cc_algo *remove_cc)
}
CC_LIST_WUNLOCK();
if (!err) {
if (!err)
/*
* Check all active control blocks across all network stacks and
* change any that are using this algorithm back to newreno. If
* the algorithm that was in use requires cleanup code to be
* run, call it.
*
* New connections already part way through being initialised
* with the CC algo we're removing will not race with this code
* because the INP_INFO_WLOCK is held during initialisation.
* We therefore don't enter the loop below until the connection
* list has stabilised.
* XXXLAS:
* - We may need to handle non-zero return values in future.
* - If we add CC framework support for protocols other than
* TCP, we may want a more generic way to handle this step.
*/
VNET_LIST_RLOCK();
VNET_FOREACH(vnet_iter) {
CURVNET_SET(vnet_iter);
INP_INFO_RLOCK(&V_tcbinfo);
LIST_FOREACH(inp, &V_tcb, inp_list) {
INP_WLOCK(inp);
/* Important to skip tcptw structs. */
if (!(inp->inp_flags & INP_TIMEWAIT) &&
(tp = intotcpcb(inp)) != NULL) {
/*
* By holding INP_WLOCK here, we are
* assured that the connection is not
* currently executing inside the CC
* module's functions i.e. it is safe
* to make the switch back to newreno.
*/
if (CC_ALGO(tp) == remove_cc) {
tmpfuncs = CC_ALGO(tp);
/*
* Newreno does not
* require any init.
*/
CC_ALGO(tp) = &newreno_cc_algo;
if (tmpfuncs->cb_destroy != NULL)
tmpfuncs->cb_destroy(tp->ccv);
}
}
INP_WUNLOCK(inp);
}
INP_INFO_RUNLOCK(&V_tcbinfo);
CURVNET_RESTORE();
}
VNET_LIST_RUNLOCK();
}
tcp_ccalgounload(remove_cc);
return (err);
}

63
sys/netinet/tcp_subr.c
View File

@ -707,6 +707,69 @@ tcp_newtcpcb(struct inpcb *inp)
return (tp); /* XXX */
}
/*
* Switch the congestion control algorithm back to NewReno for any active
* control blocks using an algorithm which is about to go away.
* This ensures the CC framework can allow the unload to proceed without leaving
* any dangling pointers which would trigger a panic.
* Returning non-zero would inform the CC framework that something went wrong
* and it would be unsafe to allow the unload to proceed. However, there is no
* way for this to occur with this implementation so we always return zero.
*/
int
tcp_ccalgounload(struct cc_algo *unload_algo)
{
struct cc_algo *tmpalgo;
struct inpcb *inp;
struct tcpcb *tp;
VNET_ITERATOR_DECL(vnet_iter);
/*
* Check all active control blocks across all network stacks and change
* any that are using "unload_algo" back to NewReno. If "unload_algo"
* requires cleanup code to be run, call it.
*/
VNET_LIST_RLOCK();
VNET_FOREACH(vnet_iter) {
CURVNET_SET(vnet_iter);
INP_INFO_RLOCK(&V_tcbinfo);
/*
* New connections already part way through being initialised
* with the CC algo we're removing will not race with this code
* because the INP_INFO_WLOCK is held during initialisation. We
* therefore don't enter the loop below until the connection
* list has stabilised.
*/
LIST_FOREACH(inp, &V_tcb, inp_list) {
INP_WLOCK(inp);
/* Important to skip tcptw structs. */
if (!(inp->inp_flags & INP_TIMEWAIT) &&
(tp = intotcpcb(inp)) != NULL) {
/*
* By holding INP_WLOCK here, we are assured
* that the connection is not currently
* executing inside the CC module's functions
* i.e. it is safe to make the switch back to
* NewReno.
*/
if (CC_ALGO(tp) == unload_algo) {
tmpalgo = CC_ALGO(tp);
/* NewReno does not require any init. */
CC_ALGO(tp) = &newreno_cc_algo;
if (tmpalgo->cb_destroy != NULL)
tmpalgo->cb_destroy(tp->ccv);
}
}
INP_WUNLOCK(inp);
}
INP_INFO_RUNLOCK(&V_tcbinfo);
CURVNET_RESTORE();
}
VNET_LIST_RUNLOCK();
return (0);
}
/*
* Drop a TCP connection, reporting
* the specified error. If connection is synchronized,

1
sys/netinet/tcp_var.h
View File

@ -605,6 +605,7 @@ VNET_DECLARE(int, tcp_ecn_maxretries);
#define V_tcp_ecn_maxretries VNET(tcp_ecn_maxretries)
int tcp_addoptions(struct tcpopt *, u_char *);
int tcp_ccalgounload(struct cc_algo *unload_algo);
struct tcpcb *
tcp_close(struct tcpcb *);
void tcp_discardcb(struct tcpcb *);