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Don't clobber td->td_retval[0] in proc_reap().

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While writing tests for CloudABI, I noticed that close() on process
descriptors returns the process ID of the child process. This is
interesting, as close() is only allowed to return 0 or -1. It turns out
that we clobber td->td_retval[0] in proc_reap(), so that wait*()
properly returns the process ID.

Change proc_reap() to leave td->td_retval[0] alone. Set the return value
in kern_wait6() instead, by keeping track of the PID before we
(potentially) reap the process.

Differential Revision:	https://reviews.freebsd.org/D3032
Reviewed by:	kib
This commit is contained in:
ed 2015-07-09 12:04:45 +00:00
parent 99ff382570
commit ed913b3a6c
1 changed files with 8 additions and 5 deletions
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13
sys/kern/kern_exit.c
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@ -839,7 +839,6 @@ proc_reap(struct thread *td, struct proc *p, int *status, int options)
q = td->td_proc;
PROC_SUNLOCK(p);
td->td_retval[0] = p->p_pid;
if (status)
*status = p->p_xstat; /* convert to int */
if (options & WNOWAIT) {
@ -1153,6 +1152,7 @@ kern_wait6(struct thread *td, idtype_t idtype, id_t id, int *status,
int options, struct __wrusage *wrusage, siginfo_t *siginfo)
{
struct proc *p, *q;
pid_t pid;
int error, nfound, ret;
AUDIT_ARG_VALUE((int)idtype); /* XXX - This is likely wrong! */
@ -1191,14 +1191,17 @@ kern_wait6(struct thread *td, idtype_t idtype, id_t id, int *status,
nfound = 0;
sx_xlock(&proctree_lock);
LIST_FOREACH(p, &q->p_children, p_sibling) {
pid = p->p_pid;
ret = proc_to_reap(td, p, idtype, id, status, options,
wrusage, siginfo, 0);
if (ret == 0)
continue;
else if (ret == 1)
nfound++;
else
else {
td->td_retval[0] = pid;
return (0);
}
PROC_LOCK(p);
PROC_SLOCK(p);
@ -1212,7 +1215,6 @@ kern_wait6(struct thread *td, idtype_t idtype, id_t id, int *status,
if ((options & WNOWAIT) == 0)
p->p_flag |= P_WAITED;
sx_xunlock(&proctree_lock);
td->td_retval[0] = p->p_pid;
if (status != NULL)
*status = W_STOPCODE(p->p_xstat);
@ -1231,6 +1233,7 @@ kern_wait6(struct thread *td, idtype_t idtype, id_t id, int *status,
p->p_pid, W_STOPCODE(p->p_xstat), p->p_xstat,
p->p_xthread != NULL ? p->p_xthread->td_tid : -1);
PROC_UNLOCK(p);
td->td_retval[0] = pid;
return (0);
}
if ((options & WUNTRACED) != 0 &&
@ -1241,7 +1244,6 @@ kern_wait6(struct thread *td, idtype_t idtype, id_t id, int *status,
if ((options & WNOWAIT) == 0)
p->p_flag |= P_WAITED;
sx_xunlock(&proctree_lock);
td->td_retval[0] = p->p_pid;
if (status != NULL)
*status = W_STOPCODE(p->p_xstat);
@ -1256,13 +1258,13 @@ kern_wait6(struct thread *td, idtype_t idtype, id_t id, int *status,
}
PROC_UNLOCK(p);
td->td_retval[0] = pid;
return (0);
}
PROC_SUNLOCK(p);
if ((options & WCONTINUED) != 0 &&
(p->p_flag & P_CONTINUED) != 0) {
sx_xunlock(&proctree_lock);
td->td_retval[0] = p->p_pid;
if ((options & WNOWAIT) == 0) {
p->p_flag &= ~P_CONTINUED;
PROC_LOCK(q);
@ -1277,6 +1279,7 @@ kern_wait6(struct thread *td, idtype_t idtype, id_t id, int *status,
siginfo->si_status = SIGCONT;
siginfo->si_code = CLD_CONTINUED;
}
td->td_retval[0] = pid;
return (0);
}
PROC_UNLOCK(p);