do_wait(WSTOPPED) assumes that p->state must be == TASK_STOPPED, this is not
true if the leader is already dead. Check SIGNAL_STOP_STOPPED instead and use
->signal->group_exit_code.
This patch is not complete if not buggy. At the very minimum it needs cleanup.
Signed-off-by: Oleg Nesterov <[email protected]>
--- PT/kernel/exit.c~6_wait_stop 2007-12-07 20:25:40.000000000 +0300
+++ PT/kernel/exit.c 2007-12-08 20:30:55.000000000 +0300
@@ -1316,6 +1316,11 @@ static int wait_task_zombie(struct task_
return retval;
}
+static inline int is_task_wait_stopped(struct task_struct *p)
+{
+ return is_task_stopped_or_traced(p) ||
+ (p->signal->flags & SIGNAL_STOP_STOPPED);
+}
/*
* Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
* read_lock(&tasklist_lock) on entry. If we return zero, we still hold
@@ -1326,29 +1331,28 @@ static int wait_task_stopped(struct task
int noreap, struct siginfo __user *infop,
int __user *stat_addr, struct rusage __user *ru)
{
- int retval, exit_code, why;
+ int retval, *p_code, exit_code, why;
uid_t uid = 0; /* unneeded, required by compiler */
pid_t pid;
exit_code = 0;
spin_lock_irq(&p->sighand->siglock);
+ if (p->ptrace & PT_PTRACED) {
+ if (!is_task_stopped_or_traced(p))
+ goto unlock_sig;
+ p_code = &p->exit_code;
+ } else {
+ if (!(p->signal->flags & SIGNAL_STOP_STOPPED))
+ goto unlock_sig;
+ p_code = &p->signal->group_exit_code;
+ }
- if (unlikely(!is_task_stopped_or_traced(p)))
- goto unlock_sig;
-
- if (!(p->ptrace & PT_PTRACED) && p->signal->group_stop_count > 0)
- /*
- * A group stop is in progress and this is the group leader.
- * We won't report until all threads have stopped.
- */
- goto unlock_sig;
-
- exit_code = p->exit_code;
+ exit_code = *p_code;
if (!exit_code)
goto unlock_sig;
if (!noreap)
- p->exit_code = 0;
+ *p_code = 0;
uid = p->uid;
unlock_sig:
@@ -1472,7 +1476,7 @@ repeat:
if (unlikely(ret < 0)) {
retval = ret;
- } else if (is_task_stopped_or_traced(p)) {
+ } else if (is_task_wait_stopped(p)) {
/*
* It's stopped now, so it might later
* continue, exit, or stop again.
--
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