Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
Roland McGrath wrote: There are other concerns. Let me see if I understand this. A thread (other than the leader) can exec and we then need to change the real_timer to wake the new task which will NOT be using the same task struct. That's correct. de_thread will turn the thread calling exec into the new leader and kill off all the other threads, including the old leader. The exec'ing thread's existing task_struct is reassigned to the PID of the original leader. My looking at the code shows that the thread leader can exit and then stays around as a zombi until the last thread in the group exits. That is correct. If an alarm comes during this wait I suspect it will wake this zombi and cause problems. You are mistaken. The signal code handles process signals sent when the leader is a zombie. The group leader sticks around with the PID that matches the TGID, until there are no live threads with its TGID. That is how process-wide kill can still work. Yes, I see, traced through the signal delivery. So Linus' patch as well as the regression of Ingo's will fix all of this. Right? -- George Anzinger george@mvista.com HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
> There are other concerns. Let me see if I understand this. A thread > (other than the leader) can exec and we then need to change the > real_timer to wake the new task which will NOT be using the same task > struct. That's correct. de_thread will turn the thread calling exec into the new leader and kill off all the other threads, including the old leader. The exec'ing thread's existing task_struct is reassigned to the PID of the original leader. > My looking at the code shows that the thread leader can exit and then > stays around as a zombi until the last thread in the group exits. That is correct. > If an alarm comes during this wait I suspect it will wake this zombi and > cause problems. You are mistaken. The signal code handles process signals sent when the leader is a zombie. The group leader sticks around with the PID that matches the TGID, until there are no live threads with its TGID. That is how process-wide kill can still work. Thanks, Roland - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
Gerd Knorr wrote:
On Thu, Aug 04, 2005 at 03:02:51PM -0700, Andrew Morton wrote:
Roland McGrath <[EMAIL PROTECTED]> wrote:
That's wrong. It has to be done only by the last thread in the group to go.
Just revert Ingo's change.
OK..
+++ 25-akpm/kernel/exit.c Thu Aug 4 15:01:06 2005
@@ -829,8 +829,10 @@ fastcall NORET_TYPE void do_exit(long co
- if (group_dead)
+ if (group_dead) {
+ del_timer_sync(>signal->real_timer);
acct_process(code);
+ }
+++ 25-akpm/kernel/posix-timers.c Thu Aug 4 15:01:06 2005
@@ -1166,7 +1166,6 @@ void exit_itimers(struct signal_struct *
- del_timer_sync(>real_timer);
That one fixes it for me.
There are other concerns. Let me see if I understand this. A thread
(other than the leader) can exec and we then need to change the
real_timer to wake the new task which will NOT be using the same task
struct.
My looking at the code shows that the thread leader can exit and then
stays around as a zombi until the last thread in the group exits. If an
alarm comes during this wait I suspect it will wake this zombi and cause
problems. So, don't we need to also change real_timer's task when the
exiting task is the real_timer wake up task, assigning it to some other
member of the group? Note, I don't say just if it is the group leader...
Then when we finally release the signal structure, we can "del" the timer.
Did I miss something here?
--
George Anzinger george@mvista.com
HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/
-
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Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
On Thu, Aug 04, 2005 at 03:02:51PM -0700, Andrew Morton wrote:
> Roland McGrath <[EMAIL PROTECTED]> wrote:
> >
> > That's wrong. It has to be done only by the last thread in the group to go.
> > Just revert Ingo's change.
> >
>
> OK..
>
> +++ 25-akpm/kernel/exit.c Thu Aug 4 15:01:06 2005
> @@ -829,8 +829,10 @@ fastcall NORET_TYPE void do_exit(long co
> - if (group_dead)
> + if (group_dead) {
> + del_timer_sync(>signal->real_timer);
> acct_process(code);
> + }
> +++ 25-akpm/kernel/posix-timers.c Thu Aug 4 15:01:06 2005
> @@ -1166,7 +1166,6 @@ void exit_itimers(struct signal_struct *
> - del_timer_sync(>real_timer);
That one fixes it for me.
Gerd
--
panic("it works"); /* avoid being flooded with debug messages */
-
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Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
On Thu, Aug 04, 2005 at 03:02:51PM -0700, Andrew Morton wrote:
Roland McGrath [EMAIL PROTECTED] wrote:
That's wrong. It has to be done only by the last thread in the group to go.
Just revert Ingo's change.
OK..
+++ 25-akpm/kernel/exit.c Thu Aug 4 15:01:06 2005
@@ -829,8 +829,10 @@ fastcall NORET_TYPE void do_exit(long co
- if (group_dead)
+ if (group_dead) {
+ del_timer_sync(tsk-signal-real_timer);
acct_process(code);
+ }
+++ 25-akpm/kernel/posix-timers.c Thu Aug 4 15:01:06 2005
@@ -1166,7 +1166,6 @@ void exit_itimers(struct signal_struct *
- del_timer_sync(sig-real_timer);
That one fixes it for me.
Gerd
--
panic(it works); /* avoid being flooded with debug messages */
-
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Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
Gerd Knorr wrote:
On Thu, Aug 04, 2005 at 03:02:51PM -0700, Andrew Morton wrote:
Roland McGrath [EMAIL PROTECTED] wrote:
That's wrong. It has to be done only by the last thread in the group to go.
Just revert Ingo's change.
OK..
+++ 25-akpm/kernel/exit.c Thu Aug 4 15:01:06 2005
@@ -829,8 +829,10 @@ fastcall NORET_TYPE void do_exit(long co
- if (group_dead)
+ if (group_dead) {
+ del_timer_sync(tsk-signal-real_timer);
acct_process(code);
+ }
+++ 25-akpm/kernel/posix-timers.c Thu Aug 4 15:01:06 2005
@@ -1166,7 +1166,6 @@ void exit_itimers(struct signal_struct *
- del_timer_sync(sig-real_timer);
That one fixes it for me.
There are other concerns. Let me see if I understand this. A thread
(other than the leader) can exec and we then need to change the
real_timer to wake the new task which will NOT be using the same task
struct.
My looking at the code shows that the thread leader can exit and then
stays around as a zombi until the last thread in the group exits. If an
alarm comes during this wait I suspect it will wake this zombi and cause
problems. So, don't we need to also change real_timer's task when the
exiting task is the real_timer wake up task, assigning it to some other
member of the group? Note, I don't say just if it is the group leader...
Then when we finally release the signal structure, we can del the timer.
Did I miss something here?
--
George Anzinger george@mvista.com
HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/
-
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Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
There are other concerns. Let me see if I understand this. A thread (other than the leader) can exec and we then need to change the real_timer to wake the new task which will NOT be using the same task struct. That's correct. de_thread will turn the thread calling exec into the new leader and kill off all the other threads, including the old leader. The exec'ing thread's existing task_struct is reassigned to the PID of the original leader. My looking at the code shows that the thread leader can exit and then stays around as a zombi until the last thread in the group exits. That is correct. If an alarm comes during this wait I suspect it will wake this zombi and cause problems. You are mistaken. The signal code handles process signals sent when the leader is a zombie. The group leader sticks around with the PID that matches the TGID, until there are no live threads with its TGID. That is how process-wide kill can still work. Thanks, Roland - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
Roland McGrath wrote: There are other concerns. Let me see if I understand this. A thread (other than the leader) can exec and we then need to change the real_timer to wake the new task which will NOT be using the same task struct. That's correct. de_thread will turn the thread calling exec into the new leader and kill off all the other threads, including the old leader. The exec'ing thread's existing task_struct is reassigned to the PID of the original leader. My looking at the code shows that the thread leader can exit and then stays around as a zombi until the last thread in the group exits. That is correct. If an alarm comes during this wait I suspect it will wake this zombi and cause problems. You are mistaken. The signal code handles process signals sent when the leader is a zombie. The group leader sticks around with the PID that matches the TGID, until there are no live threads with its TGID. That is how process-wide kill can still work. Yes, I see, traced through the signal delivery. So Linus' patch as well as the regression of Ingo's will fix all of this. Right? -- George Anzinger george@mvista.com HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/ - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
That's wrong. It has to be done only by the last thread in the group to go. Just revert Ingo's change. Thanks, Roland - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
Andrew Morton wrote:
Roland McGrath <[EMAIL PROTECTED]> wrote:
That's wrong. It has to be done only by the last thread in the group to go.
Just revert Ingo's change.
Hm... I was looking at 2.6.10 to figure it out. This looks more correct.
OK..
--- 25/kernel/exit.c~revert-timer-exit-cleanup Thu Aug 4 15:00:55 2005
+++ 25-akpm/kernel/exit.c Thu Aug 4 15:01:06 2005
@@ -829,8 +829,10 @@ fastcall NORET_TYPE void do_exit(long co
acct_update_integrals(tsk);
update_mem_hiwater(tsk);
group_dead = atomic_dec_and_test(>signal->live);
- if (group_dead)
+ if (group_dead) {
+ del_timer_sync(>signal->real_timer);
acct_process(code);
+ }
exit_mm(tsk);
exit_sem(tsk);
diff -puN kernel/posix-timers.c~revert-timer-exit-cleanup kernel/posix-timers.c
--- 25/kernel/posix-timers.c~revert-timer-exit-cleanup Thu Aug 4 15:00:55 2005
+++ 25-akpm/kernel/posix-timers.c Thu Aug 4 15:01:06 2005
@@ -1166,7 +1166,6 @@ void exit_itimers(struct signal_struct *
tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
itimer_delete(tmr);
}
- del_timer_sync(>real_timer);
}
/*
_
-
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--
George Anzinger george@mvista.com
HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/
-
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Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
Roland McGrath <[EMAIL PROTECTED]> wrote:
>
> That's wrong. It has to be done only by the last thread in the group to go.
> Just revert Ingo's change.
>
OK..
--- 25/kernel/exit.c~revert-timer-exit-cleanup Thu Aug 4 15:00:55 2005
+++ 25-akpm/kernel/exit.c Thu Aug 4 15:01:06 2005
@@ -829,8 +829,10 @@ fastcall NORET_TYPE void do_exit(long co
acct_update_integrals(tsk);
update_mem_hiwater(tsk);
group_dead = atomic_dec_and_test(>signal->live);
- if (group_dead)
+ if (group_dead) {
+ del_timer_sync(>signal->real_timer);
acct_process(code);
+ }
exit_mm(tsk);
exit_sem(tsk);
diff -puN kernel/posix-timers.c~revert-timer-exit-cleanup kernel/posix-timers.c
--- 25/kernel/posix-timers.c~revert-timer-exit-cleanup Thu Aug 4 15:00:55 2005
+++ 25-akpm/kernel/posix-timers.c Thu Aug 4 15:01:06 2005
@@ -1166,7 +1166,6 @@ void exit_itimers(struct signal_struct *
tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
itimer_delete(tmr);
}
- del_timer_sync(>real_timer);
}
/*
_
-
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Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
George Anzinger wrote:
>
> Source: MontaVista Software, Inc. George Anzinger
> Type: Defect Fix
> Description:
>
> The changes to itimer of late (after 2.6.11) cause itimers not
> to survive the exec* calls. Standard says they should.
>
> Signed-off-by: George Anzinger
>
> exit.c |1 +
> posix-timers.c |4 ++--
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
>
> Index: linux-2.6.13-rc/kernel/exit.c
> ===
> --- linux-2.6.13-rc.orig/kernel/exit.c
> +++ linux-2.6.13-rc/kernel/exit.c
> @@ -794,6 +794,7 @@ fastcall NORET_TYPE void do_exit(long co
> }
>
> tsk->flags |= PF_EXITING;
> + del_timer_sync(>signal->real_timer);
>
> /*
>* Make sure we don't try to process any timer firings
> Index: linux-2.6.13-rc/kernel/posix-timers.c
> ===
> --- linux-2.6.13-rc.orig/kernel/posix-timers.c
> +++ linux-2.6.13-rc/kernel/posix-timers.c
> @@ -1183,10 +1183,10 @@ void exit_itimers(struct signal_struct *
> struct k_itimer *tmr;
>
> while (!list_empty(>posix_timers)) {
> - tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
> + tmr = list_entry(sig->posix_timers.next,
> + struct k_itimer, list);
> itimer_delete(tmr);
> }
> - del_timer_sync(>real_timer);
> }
Yup, that's the one, thanks George.
Obvious though it is, I'll hold off on forwarding this Linuswards until
Gerd has had a chance to test it. Or did you run Gerd's test app?
-
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Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
George Anzinger george@mvista.com wrote:
Source: MontaVista Software, Inc. George Anzinger george@mvista.com
Type: Defect Fix
Description:
The changes to itimer of late (after 2.6.11) cause itimers not
to survive the exec* calls. Standard says they should.
Signed-off-by: George Anzingergeorge@mvista.com
exit.c |1 +
posix-timers.c |4 ++--
2 files changed, 3 insertions(+), 2 deletions(-)
Index: linux-2.6.13-rc/kernel/exit.c
===
--- linux-2.6.13-rc.orig/kernel/exit.c
+++ linux-2.6.13-rc/kernel/exit.c
@@ -794,6 +794,7 @@ fastcall NORET_TYPE void do_exit(long co
}
tsk-flags |= PF_EXITING;
+ del_timer_sync(tsk-signal-real_timer);
/*
* Make sure we don't try to process any timer firings
Index: linux-2.6.13-rc/kernel/posix-timers.c
===
--- linux-2.6.13-rc.orig/kernel/posix-timers.c
+++ linux-2.6.13-rc/kernel/posix-timers.c
@@ -1183,10 +1183,10 @@ void exit_itimers(struct signal_struct *
struct k_itimer *tmr;
while (!list_empty(sig-posix_timers)) {
- tmr = list_entry(sig-posix_timers.next, struct k_itimer, list);
+ tmr = list_entry(sig-posix_timers.next,
+ struct k_itimer, list);
itimer_delete(tmr);
}
- del_timer_sync(sig-real_timer);
}
Yup, that's the one, thanks George.
Obvious though it is, I'll hold off on forwarding this Linuswards until
Gerd has had a chance to test it. Or did you run Gerd's test app?
-
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Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
Roland McGrath [EMAIL PROTECTED] wrote:
That's wrong. It has to be done only by the last thread in the group to go.
Just revert Ingo's change.
OK..
--- 25/kernel/exit.c~revert-timer-exit-cleanup Thu Aug 4 15:00:55 2005
+++ 25-akpm/kernel/exit.c Thu Aug 4 15:01:06 2005
@@ -829,8 +829,10 @@ fastcall NORET_TYPE void do_exit(long co
acct_update_integrals(tsk);
update_mem_hiwater(tsk);
group_dead = atomic_dec_and_test(tsk-signal-live);
- if (group_dead)
+ if (group_dead) {
+ del_timer_sync(tsk-signal-real_timer);
acct_process(code);
+ }
exit_mm(tsk);
exit_sem(tsk);
diff -puN kernel/posix-timers.c~revert-timer-exit-cleanup kernel/posix-timers.c
--- 25/kernel/posix-timers.c~revert-timer-exit-cleanup Thu Aug 4 15:00:55 2005
+++ 25-akpm/kernel/posix-timers.c Thu Aug 4 15:01:06 2005
@@ -1166,7 +1166,6 @@ void exit_itimers(struct signal_struct *
tmr = list_entry(sig-posix_timers.next, struct k_itimer, list);
itimer_delete(tmr);
}
- del_timer_sync(sig-real_timer);
}
/*
_
-
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Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
Andrew Morton wrote:
Roland McGrath [EMAIL PROTECTED] wrote:
That's wrong. It has to be done only by the last thread in the group to go.
Just revert Ingo's change.
Hm... I was looking at 2.6.10 to figure it out. This looks more correct.
OK..
--- 25/kernel/exit.c~revert-timer-exit-cleanup Thu Aug 4 15:00:55 2005
+++ 25-akpm/kernel/exit.c Thu Aug 4 15:01:06 2005
@@ -829,8 +829,10 @@ fastcall NORET_TYPE void do_exit(long co
acct_update_integrals(tsk);
update_mem_hiwater(tsk);
group_dead = atomic_dec_and_test(tsk-signal-live);
- if (group_dead)
+ if (group_dead) {
+ del_timer_sync(tsk-signal-real_timer);
acct_process(code);
+ }
exit_mm(tsk);
exit_sem(tsk);
diff -puN kernel/posix-timers.c~revert-timer-exit-cleanup kernel/posix-timers.c
--- 25/kernel/posix-timers.c~revert-timer-exit-cleanup Thu Aug 4 15:00:55 2005
+++ 25-akpm/kernel/posix-timers.c Thu Aug 4 15:01:06 2005
@@ -1166,7 +1166,6 @@ void exit_itimers(struct signal_struct *
tmr = list_entry(sig-posix_timers.next, struct k_itimer, list);
itimer_delete(tmr);
}
- del_timer_sync(sig-real_timer);
}
/*
_
-
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--
George Anzinger george@mvista.com
HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/
-
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Re: [PATCH] Re: 2.6.12: itimer_real timers don't survive execve() any more
That's wrong. It has to be done only by the last thread in the group to go. Just revert Ingo's change. Thanks, Roland - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
