arwhite@watmath.UUCP (Alex White) (02/21/84)
Subject: Crash in PRU_ACCEPT in uipc_usrreq.c when out of mbuf's
Index: sys/sys/uipc_usrreq.c 4.2BSD
Description:
Accept -> soaccept -> uipc_usrreq(PRU_ACCEPT) -> bcopy
Bcopy dies as unp->unp_remaddr == 0
Why? Because the connect which this accept refers to,
connect -> soconnect -> uipc_usrreq(PRU_CONNECT) -> unp_connect
-> unp_connect2 -> m_copy; m_copy has run out of mbufs and returns
zero into unp->unp_remaddr.
Repeat-By:
Ya gotta be kidding, it was after 18,000 requests for memory denied
that we got this one. And there seem to be soooo many bugs that
occur if you run out, it isn't funny; you'll never get this one
a second time! you'll get hit by one of the others.
However, for anybody that wants to try, I enclose changes to
kern_exit.c so that when you run out of mbufs you won't panic the
next time a process exits...
Plea-for-help:
We keep on running out of mbufs - generally ~600 mbufs allocated
to socket structures, ~600 allocated to protocol control blocks,
and ~100 to socket names and addresses. (However, we've also
had similar crashes without the socket name and address mbufs).
We have hundreds of students running a 5-process game communicating
via pipes OR sockets in the unix domain. No, it doesn't seem
to be legitimate running out because of too many pipes.
There don't seem to be enough sitting around after the crash.
I've looked at most student's programmes, and haven't found any
yet which seems to cause any problems.
Fix:
*** uipc_usrreq.c Mon Feb 20 16:30:16 1984
--- /usr/distr/4.2/usr/sys/sys/uipc_usrreq.c Sun Sep 25 21:06:43 1983
***************
*** 371,377
case SOCK_STREAM:
unp2->unp_conn = unp;
! if (sonam) {
unp2->unp_remaddr = m_copy(sonam, 0, (int)M_COPYALL);
if(unp2->unp_remaddr == NULL) {
unp->unp_conn = 0;
--- 368,374 -----
case SOCK_STREAM:
unp2->unp_conn = unp;
! if (sonam)
unp2->unp_remaddr = m_copy(sonam, 0, (int)M_COPYALL);
soisconnected(so2);
soisconnected(so);
***************
*** 373,384
unp2->unp_conn = unp;
if (sonam) {
unp2->unp_remaddr = m_copy(sonam, 0, (int)M_COPYALL);
- if(unp2->unp_remaddr == NULL) {
- unp->unp_conn = 0;
- unp2->unp_conn = 0;
- return (ENOBUFS);
- }
- }
soisconnected(so2);
soisconnected(so);
break;
--- 370,375 -----
unp2->unp_conn = unp;
if (sonam)
unp2->unp_remaddr = m_copy(sonam, 0, (int)M_COPYALL);
soisconnected(so2);
soisconnected(so);
break;
*** kern_exit.c Fri Feb 17 05:10:18 1984
--- /usr/distr/4.2/usr/sys/sys/kern_exit.c Fri Jul 29 10:07:18 1983
***************
*** 112,124
panic("init died");
done:
p->p_xstat = rv;
! if(m == 0)
! printf("No mem for rusage for pid %d\n", p->p_pid);
! else {
! p->p_ru = mtod(m, struct rusage *);
! *p->p_ru = u.u_ru;
! ruadd(p->p_ru, &u.u_cru);
! }
for (q = proc; q < procNPROC; q++)
if (q->p_pptr == p) {
if (q->p_osptr)
--- 112,122 -----
panic("init died");
done:
p->p_xstat = rv;
! if (m == 0)
! panic("exit: m_getclr");
! p->p_ru = mtod(m, struct rusage *);
! *p->p_ru = u.u_ru;
! ruadd(p->p_ru, &u.u_cru);
for (q = proc; q < procNPROC; q++)
if (q->p_pptr == p) {
if (q->p_osptr)
***************
*** 198,204
u.u_r.r_val1 = p->p_pid;
u.u_r.r_val2 = p->p_xstat;
p->p_xstat = 0;
! if (ru && p->p_ru)
*ru = *p->p_ru;
if(p->p_ru) {
ruadd(&u.u_cru, p->p_ru);
--- 196,202 -----
u.u_r.r_val1 = p->p_pid;
u.u_r.r_val2 = p->p_xstat;
p->p_xstat = 0;
! if (ru)
*ru = *p->p_ru;
ruadd(&u.u_cru, p->p_ru);
(void) m_free(dtom(p->p_ru));
***************
*** 200,209
p->p_xstat = 0;
if (ru && p->p_ru)
*ru = *p->p_ru;
! if(p->p_ru) {
! ruadd(&u.u_cru, p->p_ru);
! (void) m_free(dtom(p->p_ru));
! }
p->p_ru = 0;
p->p_stat = NULL;
p->p_pid = 0;
--- 198,205 -----
p->p_xstat = 0;
if (ru)
*ru = *p->p_ru;
! ruadd(&u.u_cru, p->p_ru);
! (void) m_free(dtom(p->p_ru));
p->p_ru = 0;
p->p_stat = NULL;
p->p_pid = 0;