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3 Fixes -

Browse Source 
a) There was a case where a ICMP message could cause
   us to return leaving a stuck lock on an stcb.
b) The iterator needed some tweaks to fix its lock
   ordering.
c) The ITERATOR_LOCK is no longer needed in the freeing
   of a stcb. Now that the timer based one is gone we don't
   have a multiple resume situation. Add to that that there
   was somewhere a path out of the freeing of an assoc that
   did NOT release the iterator_lock.. it was time to clean
   this old code up and in the process fix the lock bug.

MFC after:	1 week
This commit is contained in:
Randall Stewart 2010-06-11 03:54:00 +00:00
parent f635c047c5
commit ec4c19fcf0
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=209029
3 changed files with 28 additions and 43 deletions
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50
sys/netinet/sctp_pcb.c
View File

@ -3075,6 +3075,11 @@ sctp_iterator_inp_being_freed(struct sctp_inpcb *inp)
} else {
it->inp = LIST_NEXT(it->inp, sctp_list);
}
/*
* When its put in the refcnt is incremented so decr
* it
*/
SCTP_INP_DECR_REF(inp);
}
it = nit;
}
@ -4428,38 +4433,6 @@ sctp_add_vtag_to_timewait(uint32_t tag, uint32_t time, uint16_t lport, uint16_t
}
static void
sctp_iterator_asoc_being_freed(struct sctp_inpcb *inp, struct sctp_tcb *stcb)
{
struct sctp_iterator *it;
/*
* Unlock the tcb lock we do this so we avoid a dead lock scenario
* where the iterator is waiting on the TCB lock and the TCB lock is
* waiting on the iterator lock.
*/
it = stcb->asoc.stcb_starting_point_for_iterator;
if (it == NULL) {
return;
}
if (it->inp != stcb->sctp_ep) {
/* hmm, focused on the wrong one? */
return;
}
if (it->stcb != stcb) {
return;
}
it->stcb = LIST_NEXT(stcb, sctp_tcblist);
if (it->stcb == NULL) {
/* done with all asoc's in this assoc */
if (it->iterator_flags & SCTP_ITERATOR_DO_SINGLE_INP) {
it->inp = NULL;
} else {
it->inp = LIST_NEXT(inp, sctp_list);
}
}
}
/*-
* Free the association after un-hashing the remote port. This
@ -4665,7 +4638,6 @@ sctp_free_assoc(struct sctp_inpcb *inp, struct sctp_tcb *stcb, int from_inpcbfre
SCTP_TCB_UNLOCK(stcb);
SCTP_ITERATOR_LOCK();
SCTP_INP_INFO_WLOCK();
SCTP_INP_WLOCK(inp);
SCTP_TCB_LOCK(stcb);
@ -4704,7 +4676,6 @@ sctp_free_assoc(struct sctp_inpcb *inp, struct sctp_tcb *stcb, int from_inpcbfre
* Make it invalid too, that way if its about to run it will abort
* and return.
*/
sctp_iterator_asoc_being_freed(inp, stcb);
/* re-increment the lock */
if (from_inpcbfree == SCTP_NORMAL_PROC) {
atomic_add_int(&stcb->asoc.refcnt, -1);
@ -4721,7 +4692,6 @@ sctp_free_assoc(struct sctp_inpcb *inp, struct sctp_tcb *stcb, int from_inpcbfre
if (from_inpcbfree == SCTP_NORMAL_PROC) {
SCTP_INP_INCR_REF(inp);
SCTP_INP_WUNLOCK(inp);
SCTP_ITERATOR_UNLOCK();
}
/* pull from vtag hash */
LIST_REMOVE(stcb, sctp_asocs);
@ -6694,20 +6664,22 @@ sctp_initiate_iterator(inp_func inpf,
it->no_chunk_output = chunk_output_off;
it->vn = curvnet;
if (s_inp) {
/* Assume lock is held here */
it->inp = s_inp;
SCTP_INP_INCR_REF(it->inp);
it->iterator_flags = SCTP_ITERATOR_DO_SINGLE_INP;
} else {
SCTP_INP_INFO_RLOCK();
it->inp = LIST_FIRST(&SCTP_BASE_INFO(listhead));
if (it->inp) {
SCTP_INP_INCR_REF(it->inp);
}
SCTP_INP_INFO_RUNLOCK();
it->iterator_flags = SCTP_ITERATOR_DO_ALL_INP;
}
SCTP_IPI_ITERATOR_WQ_LOCK();
if (it->inp) {
SCTP_INP_INCR_REF(it->inp);
}
TAILQ_INSERT_TAIL(&sctp_it_ctl.iteratorhead, it, sctp_nxt_itr);
if (sctp_it_ctl.iterator_running == 0) {
sctp_wakeup_iterator();

3
sys/netinet/sctp_usrreq.c
View File

@ -402,6 +402,9 @@ sctp_ctlinput(cmd, sa, vip)
SCTP_INP_DECR_REF(inp);
SCTP_INP_WUNLOCK(inp);
}
if (stcb) {
SCTP_TCB_UNLOCK(stcb);
}
}
}
return;

18
sys/netinet/sctputil.c
View File

@ -1255,15 +1255,20 @@ sctp_iterator_work(struct sctp_iterator *it)
{
int iteration_count = 0;
int inp_skip = 0;
int first_in = 1;
struct sctp_inpcb *tinp;
SCTP_INP_INFO_RLOCK();
SCTP_ITERATOR_LOCK();
if (it->inp) {
SCTP_INP_RLOCK(it->inp);
SCTP_INP_DECR_REF(it->inp);
}
if (it->inp == NULL) {
/* iterator is complete */
done_with_iterator:
SCTP_ITERATOR_UNLOCK();
SCTP_INP_INFO_RUNLOCK();
if (it->function_atend != NULL) {
(*it->function_atend) (it->pointer, it->val);
}
@ -1271,7 +1276,11 @@ sctp_iterator_work(struct sctp_iterator *it)
return;
}
select_a_new_ep:
SCTP_INP_RLOCK(it->inp);
if (first_in) {
first_in = 0;
} else {
SCTP_INP_RLOCK(it->inp);
}
while (((it->pcb_flags) &&
((it->inp->sctp_flags & it->pcb_flags) != it->pcb_flags)) ||
((it->pcb_features) &&
@ -1281,8 +1290,9 @@ sctp_iterator_work(struct sctp_iterator *it)
SCTP_INP_RUNLOCK(it->inp);
goto done_with_iterator;
}
SCTP_INP_RUNLOCK(it->inp);
tinp = it->inp;
it->inp = LIST_NEXT(it->inp, sctp_list);
SCTP_INP_RUNLOCK(tinp);
if (it->inp == NULL) {
goto done_with_iterator;
}
@ -1323,6 +1333,8 @@ sctp_iterator_work(struct sctp_iterator *it)
SCTP_INP_INCR_REF(it->inp);
SCTP_INP_RUNLOCK(it->inp);
SCTP_ITERATOR_UNLOCK();
SCTP_INP_INFO_RUNLOCK();
SCTP_INP_INFO_RLOCK();
SCTP_ITERATOR_LOCK();
if (sctp_it_ctl.iterator_flags) {
/* We won't be staying here */
@ -1382,9 +1394,7 @@ sctp_iterator_work(struct sctp_iterator *it)
if (it->iterator_flags & SCTP_ITERATOR_DO_SINGLE_INP) {
it->inp = NULL;
} else {
SCTP_INP_INFO_RLOCK();
it->inp = LIST_NEXT(it->inp, sctp_list);
SCTP_INP_INFO_RUNLOCK();
}
if (it->inp == NULL) {
goto done_with_iterator;