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When process is exiting, check for suspension regardless of

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multithreaded status of the process.

The stopped state must be cleared before P_WEXIT is set.  A stop
signal delivered just before first PROC_LOCK() block in exit1(9) would
put the process into pending stop with P_WEXIT set or assertion
triggered.  Also recheck for the suspension after failed
thread_single(9) call, since process lock could be dropped.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2014-12-08 16:02:02 +00:00
parent 5dc4735cb3
commit aba1ca528e
1 changed files with 16 additions and 9 deletions
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25
sys/kern/kern_exit.c
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@ -182,13 +182,14 @@ exit1(struct thread *td, int rv)
* MUST abort all other threads before proceeding past here.
*/
PROC_LOCK(p);
/*
* First check if some other thread or external request got
* here before us. If so, act appropriately: exit or suspend.
* We must ensure that stop requests are handled before we set
* P_WEXIT.
*/
thread_suspend_check(0);
while (p->p_flag & P_HADTHREADS) {
/*
* First check if some other thread got here before us.
* If so, act appropriately: exit or suspend.
*/
thread_suspend_check(0);
/*
* Kill off the other threads. This requires
* some co-operation from other parts of the kernel
@ -207,12 +208,18 @@ exit1(struct thread *td, int rv)
* either be suspended there or exit.
*/
if (!thread_single(SINGLE_EXIT))
/*
* All other activity in this process is now
* stopped. Threading support has been turned
* off.
*/
break;
/*
* All other activity in this process is now stopped.
* Threading support has been turned off.
* Recheck for new stop or suspend requests which
* might appear while process lock was dropped in
* thread_single().
*/
thread_suspend_check(0);
}
KASSERT(p->p_numthreads == 1,
("exit1: proc %p exiting with %d threads", p, p->p_numthreads));