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Back out scanning file descriptors with holding a process lock.

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selrecord() requires allproc sx in pfind(), resulting in lock order
reversal between allproc and a process lock.
This commit is contained in:
tanimura 2001-05-15 10:19:57 +00:00
parent 6125cb47e3
commit ac163f8025
3 changed files with 66 additions and 6 deletions
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36
sys/kern/sys_generic.c
View File

@ -768,13 +768,29 @@ select(p, uap)
retry:
ncoll = nselcoll;
p->p_flag |= P_SELECT;
PROC_UNLOCK(p);
error = selscan(p, ibits, obits, uap->nd);
PROC_LOCK(p);
if (error || p->p_retval[0])
goto done;
if (atv.tv_sec || atv.tv_usec) {
getmicrouptime(&rtv);
if (timevalcmp(&rtv, &atv, >=))
if (timevalcmp(&rtv, &atv, >=)) {
/*
* An event of our interest may occur during locking a process.
* In order to avoid missing the event that occured during locking
* the process, test P_SELECT and rescan file descriptors if
* necessary.
*/
if ((p->p_flag & P_SELECT) == 0 || nselcoll != ncoll) {
ncoll = nselcoll;
p->p_flag |= P_SELECT;
PROC_UNLOCK(p);
error = selscan(p, ibits, obits, uap->nd);
PROC_LOCK(p);
}
goto done;
}
ttv = atv;
timevalsub(&ttv, &rtv);
timo = ttv.tv_sec > 24 * 60 * 60 ?
@ -958,13 +974,29 @@ poll(p, uap)
retry:
ncoll = nselcoll;
p->p_flag |= P_SELECT;
PROC_UNLOCK(p);
error = pollscan(p, (struct pollfd *)bits, nfds);
PROC_LOCK(p);
if (error || p->p_retval[0])
goto done;
if (atv.tv_sec || atv.tv_usec) {
getmicrouptime(&rtv);
if (timevalcmp(&rtv, &atv, >=))
if (timevalcmp(&rtv, &atv, >=)) {
/*
* An event of our interest may occur during locking a process.
* In order to avoid missing the event that occured during locking
* the process, test P_SELECT and rescan file descriptors if
* necessary.
*/
if ((p->p_flag & P_SELECT) == 0 || nselcoll != ncoll) {
ncoll = nselcoll;
p->p_flag |= P_SELECT;
PROC_UNLOCK(p);
error = pollscan(p, (struct pollfd *)bits, nfds);
PROC_LOCK(p);
}
goto done;
}
ttv = atv;
timevalsub(&ttv, &rtv);
timo = ttv.tv_sec > 24 * 60 * 60 ?

18
sys/netncp/ncp_sock.c
View File

@ -202,17 +202,31 @@ ncp_sock_rselect(struct socket *so,struct proc *p, struct timeval *tv, int event
}
timo = 0;
PROC_LOCK(p);
retry:
p->p_flag |= P_SELECT;
PROC_UNLOCK(p);
error = ncp_poll(so, events);
PROC_LOCK(p);
if (error) {
error = 0;
goto done;
}
if (tv) {
getmicrouptime(&rtv);
if (timevalcmp(&rtv, &atv, >=))
if (timevalcmp(&rtv, &atv, >=)) {
/*
* An event of our interest may occur during locking a process.
* In order to avoid missing the event that occured during locking
* the process, test P_SELECT and rescan file descriptors if
* necessary.
*/
if ((p->p_flag & P_SELECT) == 0) {
p->p_flag |= P_SELECT;
PROC_UNLOCK(p);
error = ncp_poll(so, events);
PROC_LOCK(p);
}
goto done;
}
ttv=atv;
timevalsub(&ttv, &rtv);
timo = tvtohz(&ttv);

18
sys/netsmb/smb_trantcp.c
View File

@ -114,17 +114,31 @@ nbssn_rselect(struct nbpcb *nbp, struct timeval *tv, int events, struct proc *p)
}
timo = 0;
PROC_LOCK(p);
retry:
p->p_flag |= P_SELECT;
PROC_UNLOCK(p);
error = nb_poll(nbp, events, p);
PROC_LOCK(p);
if (error) {
error = 0;
goto done;
}
if (tv) {
getmicrouptime(&rtv);
if (timevalcmp(&rtv, &atv, >=))
if (timevalcmp(&rtv, &atv, >=)) {
/*
* An event of our interest may occur during locking a process.
* In order to avoid missing the event that occured during locking
* the process, test P_SELECT and rescan file descriptors if
* necessary.
*/
if ((p->p_flag & P_SELECT) == 0) {
p->p_flag |= P_SELECT;
PROC_UNLOCK(p);
error = nb_poll(nbp, events, p);
PROC_LOCK(p);
}
goto done;
}
ttv = atv;
timevalsub(&ttv, &rtv);
timo = tvtohz(&ttv);