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MFC r282679:

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Do not return from thread_single(SINGLE_BOUNDARY) until all stopped
thread are guarenteed to be removed from the processors.
This commit is contained in:
kib 2015-05-16 09:13:56 +00:00
parent 0ecfe385ea
commit 0f07927a1e
1 changed files with 23 additions and 0 deletions
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23
sys/kern/kern_thread.c
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@ -758,6 +758,29 @@ thread_single(struct proc *p, int mode)
PROC_LOCK(p);
PROC_SLOCK(p);
}
} else if (mode == SINGLE_BOUNDARY) {
/*
* Wait until all suspended threads are removed from
* the processors. The thread_suspend_check()
* increments p_boundary_count while it is still
* running, which makes it possible for the execve()
* to destroy vmspace while our other threads are
* still using the address space.
*
* We lock the thread, which is only allowed to
* succeed after context switch code finished using
* the address space.
*/
FOREACH_THREAD_IN_PROC(p, td2) {
if (td2 == td)
continue;
thread_lock(td2);
KASSERT((td2->td_flags & TDF_BOUNDARY) != 0,
("td %p not on boundary", td2));
KASSERT(TD_IS_SUSPENDED(td2),
("td %p is not suspended", td2));
thread_unlock(td2);
}
}
PROC_SUNLOCK(p);
return (0);