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Ignore stop and continue signals sent to an exiting process. Stop signals

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set p_xstat to the signal that triggered the stop, but p_xstat is also
used to hold the exit status of an exiting process.  Without this change,
a stop signal that arrived after a process was marked P_WEXIT but before
it was marked a zombie would overwrite the exit status with the stop signal
number.

Reviewed by:	kib
MFC after:	1 week
This commit is contained in:
John Baldwin 2012-09-13 15:51:18 +00:00
parent 2bfb8a83f6
commit 0f14f15b62
2 changed files with 13 additions and 2 deletions
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8
sys/kern/kern_exit.c
View File

@ -199,6 +199,14 @@ exit1(struct thread *td, int rv)
*/
_STOPEVENT(p, S_EXIT, rv);
/*
* Ignore any pending request to stop due to a stop signal.
* Once P_WEXIT is set, future requests will be ignored as
* well.
*/
p->p_flag &= ~P_STOPPED_SIG;
KASSERT(!P_SHOULDSTOP(p), ("exiting process is stopped"));
/*
* Note that we are exiting and do another wakeup of anyone in
* PIOCWAIT in case they aren't listening for S_EXIT stops or

7
sys/kern/kern_sig.c
View File

@ -2134,6 +2134,8 @@ tdsendsignal(struct proc *p, struct thread *td, int sig, ksiginfo_t *ksi)
* We try do the per-process part here.
*/
if (P_SHOULDSTOP(p)) {
KASSERT(!(p->p_flag & P_WEXIT),
("signal to stopped but exiting process"));
if (sig == SIGKILL) {
/*
* If traced process is already stopped,
@ -2248,7 +2250,7 @@ tdsendsignal(struct proc *p, struct thread *td, int sig, ksiginfo_t *ksi)
MPASS(action == SIG_DFL);
if (prop & SA_STOP) {
if (p->p_flag & P_PPWAIT)
if (p->p_flag & (P_PPWAIT|P_WEXIT))
goto out;
p->p_flag |= P_STOPPED_SIG;
p->p_xstat = sig;
@ -2410,6 +2412,7 @@ ptracestop(struct thread *td, int sig)
struct proc *p = td->td_proc;
PROC_LOCK_ASSERT(p, MA_OWNED);
KASSERT(!(p->p_flag & P_WEXIT), ("Stopping exiting process"));
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK,
&p->p_mtx.lock_object, "Stopping for traced signal");
@ -2648,7 +2651,7 @@ issignal(struct thread *td, int stop_allowed)
* process group, ignore tty stop signals.
*/
if (prop & SA_STOP) {
if (p->p_flag & P_TRACED ||
if (p->p_flag & (P_TRACED|P_WEXIT) ||
(p->p_pgrp->pg_jobc == 0 &&
prop & SA_TTYSTOP))
break; /* == ignore */