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Re: [RFC PATCH 5/5] Add a Signal Control Group Subsystem [message #29734] Wed, 23 April 2008 15:17 Go to next message
Cedric Le Goater is currently offline  Cedric Le Goater
Messages: 443
Registered: February 2006
Senior Member
Hello Matt !

> Add a signal control group subsystem that allows us to send signals to all tasks
> in the control group by writing the desired signal(7) number to the kill file.
> 
> NOTE: We don't really need per-cgroup state, but control groups doesn't support
> stateless subsystems yet.
> 
> Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
> ---
>  include/linux/cgroup_signal.h |   28 +++++++++
>  include/linux/cgroup_subsys.h |    6 +
>  init/Kconfig                  |    6 +
>  kernel/Makefile               |    1 
>  kernel/cgroup_signal.c        |  129 ++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 170 insertions(+)


I think there is a small race with new tasks entering the cgroup
while it's beeing killed, and a _fork ops would handle that. nop ? 

Thanks,

C. 
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Re: [RFC PATCH 5/5] Add a Signal Control Group Subsystem [message #29737 is a reply to message #29734] Wed, 23 April 2008 15:37 Go to previous messageGo to next message
Paul Menage is currently offline  Paul Menage
Messages: 642
Registered: September 2006
Senior Member
On Wed, Apr 23, 2008 at 8:17 AM, Cedric Le Goater <clg@fr.ibm.com> wrote:
> Hello Matt !
>
>  > Add a signal control group subsystem that allows us to send signals to all tasks
>  > in the control group by writing the desired signal(7) number to the kill file.
>  >
>  > NOTE: We don't really need per-cgroup state, but control groups doesn't support
>  > stateless subsystems yet.
>  >
>  > Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
>  > ---
>  >  include/linux/cgroup_signal.h |   28 +++++++++
>  >  include/linux/cgroup_subsys.h |    6 +
>  >  init/Kconfig                  |    6 +
>  >  kernel/Makefile               |    1
>  >  kernel/cgroup_signal.c        |  129 ++++++++++++++++++++++++++++++++++++++++++
>  >  5 files changed, 170 insertions(+)
>
>
>  I think there is a small race with new tasks entering the cgroup
>  while it's beeing killed, and a _fork ops would handle that. nop ?
>

I never saw the actual patch (what lists did it go out to?) but I
suspect that this is one of those operations that's just going to be
inherently racy, and that the API should guarantee to affect all tasks
that are members of the group for the entirety of the operation, but
with no guarantees about what happens to tasks that enter or leave in
the meantime.

Paul
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Re: [RFC PATCH 5/5] Add a Signal Control Group Subsystem [message #29756 is a reply to message #29737] Thu, 24 April 2008 07:00 Go to previous message
Matt Helsley is currently offline  Matt Helsley
Messages: 86
Registered: August 2006
Member
On Wed, 2008-04-23 at 08:37 -0700, Paul Menage wrote:
> On Wed, Apr 23, 2008 at 8:17 AM, Cedric Le Goater <clg@fr.ibm.com> wrote:
> > Hello Matt !
> >
> >  > Add a signal control group subsystem that allows us to send signals to all tasks
> >  > in the control group by writing the desired signal(7) number to the kill file.
> >  >
> >  > NOTE: We don't really need per-cgroup state, but control groups doesn't support
> >  > stateless subsystems yet.
> >  >
> >  > Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
> >  > ---
> >  >  include/linux/cgroup_signal.h |   28 +++++++++
> >  >  include/linux/cgroup_subsys.h |    6 +
> >  >  init/Kconfig                  |    6 +
> >  >  kernel/Makefile               |    1
> >  >  kernel/cgroup_signal.c        |  129 ++++++++++++++++++++++++++++++++++++++++++
> >  >  5 files changed, 170 insertions(+)
> >
> >
> >  I think there is a small race with new tasks entering the cgroup
> >  while it's beeing killed, and a _fork ops would handle that. nop ?
> >
> 
> I never saw the actual patch (what lists did it go out to?) but I

Hi Paul,

	Sorry about this. MTA issues again :(. I think I've gotten them fixed
*this* time. I've resent them and you should have received your own copy
this time. Please let me know if you still aren't receiving them.

Cheers,
	-Matt

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