svn commit: r223088 - in head/sys: kern sys

[David E. O'Brien]

Author: obrien
Date: Tue Jun 14 17:09:30 2011
New Revision: 223088
URL: http://svn.freebsd.org/changeset/base/223088

Log:
  We should not return ECHILD when debugging a child and the parent does a
  "wait4(-1, ..., WNOHANG, ...)".  Instead wait(2) should behave as if the
  child does not wish to report status at this time.
  
  Reviewed by:	jhb

Modified:
  head/sys/kern/kern_exit.c
  head/sys/kern/sys_process.c
  head/sys/sys/proc.h

Modified: head/sys/kern/kern_exit.c
==============================================================================
--- head/sys/kern/kern_exit.c	Tue Jun 14 16:50:29 2011	(r223087)
+++ head/sys/kern/kern_exit.c	Tue Jun 14 17:09:30 2011	(r223088)
@@ -701,8 +701,9 @@ proc_reap(struct thread *td, struct proc
 	 */
 	if (p->p_oppid && (t = pfind(p->p_oppid)) != NULL) {
 		PROC_LOCK(p);
-		p->p_oppid = 0;
 		proc_reparent(p, t);
+		p->p_pptr->p_dbg_child--;
+		p->p_oppid = 0;
 		PROC_UNLOCK(p);
 		pksignal(t, SIGCHLD, p->p_ksi);
 		wakeup(t);
@@ -794,7 +795,8 @@ kern_wait(struct thread *td, pid_t pid, 
 		pid = -q->p_pgid;
 		PROC_UNLOCK(q);
 	}
-	if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WNOWAIT|WLINUXCLONE))
+	/* If we don't know the option, just return. */
+	if (options & ~(WUNTRACED|WNOHANG|WCONTINUED|WNOWAIT|WLINUXCLONE))
 		return (EINVAL);
 loop:
 	if (q->p_flag & P_STATCHILD) {
@@ -873,7 +875,10 @@ loop:
 	}
 	if (nfound == 0) {
 		sx_xunlock(&proctree_lock);
-		return (ECHILD);
+		if (td->td_proc->p_dbg_child)
+			return (0);
+		else
+			return (ECHILD);
 	}
 	if (options & WNOHANG) {
 		sx_xunlock(&proctree_lock);

Modified: head/sys/kern/sys_process.c
==============================================================================
--- head/sys/kern/sys_process.c	Tue Jun 14 16:50:29 2011	(r223087)
+++ head/sys/kern/sys_process.c	Tue Jun 14 17:09:30 2011	(r223088)
@@ -831,8 +831,11 @@ kern_ptrace(struct thread *td, int req, 
 		/* security check done above */
 		p->p_flag |= P_TRACED;
 		p->p_oppid = p->p_pptr->p_pid;
-		if (p->p_pptr != td->td_proc)
+		if (p->p_pptr != td->td_proc) {
+			/* Remember that a child is being debugged(traced). */
+			p->p_pptr->p_dbg_child++;
 			proc_reparent(p, td->td_proc);
+		}
 		data = SIGSTOP;
 		goto sendsig;	/* in PT_CONTINUE below */
 
@@ -919,11 +922,12 @@ kern_ptrace(struct thread *td, int req, 
 					PROC_UNLOCK(pp);
 				PROC_LOCK(p);
 				proc_reparent(p, pp);
+				p->p_pptr->p_dbg_child--;
 				if (pp == initproc)
 					p->p_sigparent = SIGCHLD;
 			}
-			p->p_flag &= ~(P_TRACED | P_WAITED | P_FOLLOWFORK);
 			p->p_oppid = 0;
+			p->p_flag &= ~(P_TRACED | P_WAITED | P_FOLLOWFORK);
 
 			/* should we send SIGCHLD? */
 			/* childproc_continued(p); */

Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h	Tue Jun 14 16:50:29 2011	(r223087)
+++ head/sys/sys/proc.h	Tue Jun 14 17:09:30 2011	(r223088)
@@ -503,6 +503,8 @@ struct proc {
 /* The following fields are all zeroed upon creation in fork. */
 #define	p_startzero	p_oppid
 	pid_t		p_oppid;	/* (c + e) Save ppid in ptrace. XXX */
+	int		p_dbg_child;	/* (c + e) # of debugged children in
+							ptrace. */
 	struct vmspace	*p_vmspace;	/* (b) Address space. */
 	u_int		p_swtick;	/* (c) Tick when swapped in or out. */
 	struct itimerval p_realtimer;	/* (c) Alarm timer. */