* [RFC] decrease tsk->signal->live before profile_task_exit
@ 2020-05-28 4:09 liuchao
2020-05-29 18:01 ` Eric W. Biederman
0 siblings, 1 reply; 3+ messages in thread
From: liuchao @ 2020-05-28 4:09 UTC (permalink / raw)
To: mingo, tglx; +Cc: linux-kernel, hushiyuan, hewenliang4, liuchao
I want to dermine which thread is the last one to enter
do_exit in profile_task_exit. But when a lot of threads
exit, tsk->signal->live is not correct since it decrease
after profile_task_exit.
Signed-off-by: liuchao <liuchao173@huawei.com>
---
kernel/exit.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/exit.c b/kernel/exit.c
index ce2a75bc0ade..1693764bc356 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -708,6 +708,7 @@ void __noreturn do_exit(long code)
struct task_struct *tsk = current;
int group_dead;
+ group_dead = atomic_dec_and_test(&tsk->signal->live);
profile_task_exit(tsk);
kcov_task_exit(tsk);
@@ -755,7 +756,6 @@ void __noreturn do_exit(long code)
if (tsk->mm)
sync_mm_rss(tsk->mm);
acct_update_integrals(tsk);
- group_dead = atomic_dec_and_test(&tsk->signal->live);
if (group_dead) {
/*
* If the last thread of global init has exited, panic
--
2.19.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RFC] decrease tsk->signal->live before profile_task_exit
2020-05-28 4:09 [RFC] decrease tsk->signal->live before profile_task_exit liuchao
@ 2020-05-29 18:01 ` Eric W. Biederman
0 siblings, 0 replies; 3+ messages in thread
From: Eric W. Biederman @ 2020-05-29 18:01 UTC (permalink / raw)
To: liuchao; +Cc: mingo, tglx, linux-kernel, hushiyuan, hewenliang4
liuchao <liuchao173@huawei.com> writes:
> I want to dermine which thread is the last one to enter
> do_exit in profile_task_exit. But when a lot of threads
> exit, tsk->signal->live is not correct since it decrease
> after profile_task_exit.
I don't think that would be wise.
Any additional code before the sanity checks at the start of do_exit
seems like a bad idea.
We could probably move the decrement of tsk->signal->live a little
earlier, but not that much earlier in the function.
Does profile_task_exit even make sense that early in the code? If the
code is doing much of anything that is a completely inappopriate
placement of profile_task_exit.
Eric
> Signed-off-by: liuchao <liuchao173@huawei.com>
> ---
> kernel/exit.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/exit.c b/kernel/exit.c
> index ce2a75bc0ade..1693764bc356 100644
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -708,6 +708,7 @@ void __noreturn do_exit(long code)
> struct task_struct *tsk = current;
> int group_dead;
>
> + group_dead = atomic_dec_and_test(&tsk->signal->live);
> profile_task_exit(tsk);
> kcov_task_exit(tsk);
>
> @@ -755,7 +756,6 @@ void __noreturn do_exit(long code)
> if (tsk->mm)
> sync_mm_rss(tsk->mm);
> acct_update_integrals(tsk);
> - group_dead = atomic_dec_and_test(&tsk->signal->live);
> if (group_dead) {
> /*
> * If the last thread of global init has exited, panic
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC] decrease tsk->signal->live before profile_task_exit
@ 2020-06-09 2:30 liuchao (CR)
0 siblings, 0 replies; 3+ messages in thread
From: liuchao (CR) @ 2020-06-09 2:30 UTC (permalink / raw)
To: Eric W. Biederman; +Cc: mingo, tglx, linux-kernel, Hushiyuan, hewenliang (C)
Eric W. Biederman <mailto:ebiederm@xmission.com> writes:
> liuchao <liuchao173@huawei.com> writes:
>
> > I want to dermine which thread is the last one to enter do_exit in
> > profile_task_exit. But when a lot of threads exit, tsk->signal->live
> > is not correct since it decrease after profile_task_exit.
>
> I don't think that would be wise.
>
> Any additional code before the sanity checks at the start of do_exit seems
> like a bad idea.
>
> We could probably move the decrement of tsk->signal->live a little earlier,
> but not that much earlier in the function.
>
> Does profile_task_exit even make sense that early in the code? If the code
> is doing much of anything that is a completely inappopriate placement of
> profile_task_exit.
I think so too.
Move the decrement of tsk->signal->live after the sanity checks, then
profile_task_exit and kcov_task_exit make more sense.
>
> Eric
>
>
> > Signed-off-by: liuchao <liuchao173@huawei.com>
> > ---
> > kernel/exit.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/exit.c b/kernel/exit.c index
> > ce2a75bc0ade..1693764bc356 100644
> > --- a/kernel/exit.c
> > +++ b/kernel/exit.c
> > @@ -708,6 +708,7 @@ void __noreturn do_exit(long code)
> > struct task_struct *tsk = current;
> > int group_dead;
> >
> > + group_dead = atomic_dec_and_test(&tsk->signal->live);
> > profile_task_exit(tsk);
> > kcov_task_exit(tsk);
> >
> > @@ -755,7 +756,6 @@ void __noreturn do_exit(long code)
> > if (tsk->mm)
> > sync_mm_rss(tsk->mm);
> > acct_update_integrals(tsk);
> > - group_dead = atomic_dec_and_test(&tsk->signal->live);
> > if (group_dead) {
> > /*
> > * If the last thread of global init has exited, panic
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-06-09 2:30 UTC | newest]
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2020-05-29 18:01 ` Eric W. Biederman
2020-06-09 2:30 liuchao (CR)
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