Author: jhb
Date: Tue Feb 26 21:05:06 2013
New Revision: 247350
URL: http://svnweb.freebsd.org/changeset/base/247350
Log:
MFC 240467:
Ignore stop and continue signals sent to an exiting process. Stop signals
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.
Modified:
stable/8/sys/kern/kern_exit.c
stable/8/sys/kern/kern_sig.c
Directory Properties:
stable/8/sys/ (props changed)
stable/8/sys/kern/ (props changed)
Modified: stable/8/sys/kern/kern_exit.c
==============================================================================
--- stable/8/sys/kern/kern_exit.c Tue Feb 26 21:04:58 2013
(r247349)
+++ stable/8/sys/kern/kern_exit.c Tue Feb 26 21:05:06 2013
(r247350)
@@ -183,6 +183,14 @@ 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
* decided to wait again after we told them we are exiting.
Modified: stable/8/sys/kern/kern_sig.c
==============================================================================
--- stable/8/sys/kern/kern_sig.c Tue Feb 26 21:04:58 2013
(r247349)
+++ stable/8/sys/kern/kern_sig.c Tue Feb 26 21:05:06 2013
(r247350)
@@ -2142,6 +2142,8 @@ tdsignal(struct proc *p, struct thread *
* 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,
@@ -2256,7 +2258,7 @@ tdsignal(struct proc *p, struct thread *
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;
@@ -2418,6 +2420,7 @@ 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");
@@ -2658,7 +2661,7 @@ issignal(struct thread *td, int stop_all
* 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 */
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