svn commit: r232693 - in stable/9/sys: kern sys
Konstantin Belousov
kib at FreeBSD.org
Thu Mar 8 12:54:27 UTC 2012
Author: kib
Date: Thu Mar 8 12:54:26 2012
New Revision: 232693
URL: http://svn.freebsd.org/changeset/base/232693
Log:
MFC r232048:
Allow the parent to gather the exit status of the children reparented
to the debugger. When reparenting for debugging, keep the child in
the new orphan list of old parent. When looping over the children in
kern_wait(), iterate over both children list and orphan list to search
for the process by pid.
MFC r232104:
Restore the return statement erronously removed in the r232048.
In order to keep stable/9 KBI, the p_dbg_child member of struct proc
was replaced with padding.
Modified:
stable/9/sys/kern/kern_exit.c
stable/9/sys/kern/kern_fork.c
stable/9/sys/kern/sys_process.c
stable/9/sys/sys/proc.h
Directory Properties:
stable/9/sys/ (props changed)
Modified: stable/9/sys/kern/kern_exit.c
==============================================================================
--- stable/9/sys/kern/kern_exit.c Thu Mar 8 12:49:08 2012 (r232692)
+++ stable/9/sys/kern/kern_exit.c Thu Mar 8 12:54:26 2012 (r232693)
@@ -720,7 +720,6 @@ proc_reap(struct thread *td, struct proc
if (p->p_oppid && (t = pfind(p->p_oppid)) != NULL) {
PROC_LOCK(p);
proc_reparent(p, t);
- p->p_pptr->p_dbg_child--;
p->p_oppid = 0;
PROC_UNLOCK(p);
pksignal(t, SIGCHLD, p->p_ksi);
@@ -739,6 +738,10 @@ proc_reap(struct thread *td, struct proc
LIST_REMOVE(p, p_list); /* off zombproc */
sx_xunlock(&allproc_lock);
LIST_REMOVE(p, p_sibling);
+ if (p->p_flag & P_ORPHAN) {
+ LIST_REMOVE(p, p_orphan);
+ p->p_flag &= ~P_ORPHAN;
+ }
leavepgrp(p);
#ifdef PROCDESC
if (p->p_procdesc != NULL)
@@ -803,12 +806,53 @@ proc_reap(struct thread *td, struct proc
sx_xunlock(&allproc_lock);
}
+static int
+proc_to_reap(struct thread *td, struct proc *p, pid_t pid, int *status,
+ int options, struct rusage *rusage)
+{
+ struct proc *q;
+
+ q = td->td_proc;
+ PROC_LOCK(p);
+ if (pid != WAIT_ANY && p->p_pid != pid && p->p_pgid != -pid) {
+ PROC_UNLOCK(p);
+ return (0);
+ }
+ if (p_canwait(td, p)) {
+ PROC_UNLOCK(p);
+ return (0);
+ }
+
+ /*
+ * This special case handles a kthread spawned by linux_clone
+ * (see linux_misc.c). The linux_wait4 and linux_waitpid
+ * functions need to be able to distinguish between waiting
+ * on a process and waiting on a thread. It is a thread if
+ * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
+ * signifies we want to wait for threads and not processes.
+ */
+ if ((p->p_sigparent != SIGCHLD) ^
+ ((options & WLINUXCLONE) != 0)) {
+ PROC_UNLOCK(p);
+ return (0);
+ }
+
+ PROC_SLOCK(p);
+ if (p->p_state == PRS_ZOMBIE) {
+ proc_reap(td, p, status, options, rusage);
+ return (-1);
+ }
+ PROC_SUNLOCK(p);
+ PROC_UNLOCK(p);
+ return (1);
+}
+
int
kern_wait(struct thread *td, pid_t pid, int *status, int options,
struct rusage *rusage)
{
struct proc *p, *q;
- int error, nfound;
+ int error, nfound, ret;
AUDIT_ARG_PID(pid);
AUDIT_ARG_VALUE(options);
@@ -831,37 +875,16 @@ loop:
nfound = 0;
sx_xlock(&proctree_lock);
LIST_FOREACH(p, &q->p_children, p_sibling) {
- PROC_LOCK(p);
- if (pid != WAIT_ANY &&
- p->p_pid != pid && p->p_pgid != -pid) {
- PROC_UNLOCK(p);
- continue;
- }
- if (p_canwait(td, p)) {
- PROC_UNLOCK(p);
+ ret = proc_to_reap(td, p, pid, status, options, rusage);
+ if (ret == 0)
continue;
- }
-
- /*
- * This special case handles a kthread spawned by linux_clone
- * (see linux_misc.c). The linux_wait4 and linux_waitpid
- * functions need to be able to distinguish between waiting
- * on a process and waiting on a thread. It is a thread if
- * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
- * signifies we want to wait for threads and not processes.
- */
- if ((p->p_sigparent != SIGCHLD) ^
- ((options & WLINUXCLONE) != 0)) {
- PROC_UNLOCK(p);
- continue;
- }
+ else if (ret == 1)
+ nfound++;
+ else
+ return (0);
- nfound++;
+ PROC_LOCK(p);
PROC_SLOCK(p);
- if (p->p_state == PRS_ZOMBIE) {
- proc_reap(td, p, status, options, rusage);
- return (0);
- }
if ((p->p_flag & P_STOPPED_SIG) &&
(p->p_suspcount == p->p_numthreads) &&
(p->p_flag & P_WAITED) == 0 &&
@@ -897,12 +920,31 @@ loop:
}
PROC_UNLOCK(p);
}
+
+ /*
+ * Look in the orphans list too, to allow the parent to
+ * collect it's child exit status even if child is being
+ * debugged.
+ *
+ * Debugger detaches from the parent upon successful
+ * switch-over from parent to child. At this point due to
+ * re-parenting the parent loses the child to debugger and a
+ * wait4(2) call would report that it has no children to wait
+ * for. By maintaining a list of orphans we allow the parent
+ * to successfully wait until the child becomes a zombie.
+ */
+ LIST_FOREACH(p, &q->p_orphans, p_orphan) {
+ ret = proc_to_reap(td, p, pid, status, options, rusage);
+ if (ret == 0)
+ continue;
+ else if (ret == 1)
+ nfound++;
+ else
+ return (0);
+ }
if (nfound == 0) {
sx_xunlock(&proctree_lock);
- if (td->td_proc->p_dbg_child)
- return (0);
- else
- return (ECHILD);
+ return (ECHILD);
}
if (options & WNOHANG) {
sx_xunlock(&proctree_lock);
@@ -940,5 +982,15 @@ proc_reparent(struct proc *child, struct
PROC_UNLOCK(child->p_pptr);
LIST_REMOVE(child, p_sibling);
LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
+
+ if (child->p_flag & P_ORPHAN) {
+ LIST_REMOVE(child, p_orphan);
+ child->p_flag &= ~P_ORPHAN;
+ }
+ if (child->p_flag & P_TRACED) {
+ LIST_INSERT_HEAD(&child->p_pptr->p_orphans, child, p_orphan);
+ child->p_flag |= P_ORPHAN;
+ }
+
child->p_pptr = parent;
}
Modified: stable/9/sys/kern/kern_fork.c
==============================================================================
--- stable/9/sys/kern/kern_fork.c Thu Mar 8 12:49:08 2012 (r232692)
+++ stable/9/sys/kern/kern_fork.c Thu Mar 8 12:54:26 2012 (r232693)
@@ -590,6 +590,7 @@ do_fork(struct thread *td, int flags, st
LIST_INSERT_AFTER(p1, p2, p_pglist);
PGRP_UNLOCK(p1->p_pgrp);
LIST_INIT(&p2->p_children);
+ LIST_INIT(&p2->p_orphans);
callout_init(&p2->p_itcallout, CALLOUT_MPSAFE);
Modified: stable/9/sys/kern/sys_process.c
==============================================================================
--- stable/9/sys/kern/sys_process.c Thu Mar 8 12:49:08 2012 (r232692)
+++ stable/9/sys/kern/sys_process.c Thu Mar 8 12:54:26 2012 (r232693)
@@ -841,8 +841,6 @@ kern_ptrace(struct thread *td, int req,
p->p_flag |= P_TRACED;
p->p_oppid = p->p_pptr->p_pid;
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;
@@ -931,7 +929,6 @@ 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;
}
Modified: stable/9/sys/sys/proc.h
==============================================================================
--- stable/9/sys/sys/proc.h Thu Mar 8 12:49:08 2012 (r232692)
+++ stable/9/sys/sys/proc.h Thu Mar 8 12:54:26 2012 (r232693)
@@ -506,8 +506,7 @@ 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. */
+ int p_pad_dbg_child;
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. */
@@ -575,6 +574,14 @@ struct proc {
after fork. */
uint64_t p_prev_runtime; /* (c) Resource usage accounting. */
struct racct *p_racct; /* (b) Resource accounting. */
+ /*
+ * An orphan is the child that has beed re-parented to the
+ * debugger as a result of attaching to it. Need to keep
+ * track of them for parent to be able to collect the exit
+ * status of what used to be children.
+ */
+ LIST_ENTRY(proc) p_orphan; /* (e) List of orphan processes. */
+ LIST_HEAD(, proc) p_orphans; /* (e) Pointer to list of orphans. */
};
#define p_session p_pgrp->pg_session
@@ -613,6 +620,7 @@ struct proc {
#define P_HWPMC 0x800000 /* Process is using HWPMCs */
#define P_JAILED 0x1000000 /* Process is in jail. */
+#define P_ORPHAN 0x2000000 /* Orphaned. */
#define P_INEXEC 0x4000000 /* Process is in execve(). */
#define P_STATCHILD 0x8000000 /* Child process stopped or exited. */
#define P_INMEM 0x10000000 /* Loaded into memory. */
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