[RFC PATCH 5/5] Add a Signal Control Group Subsystem

Paul Menage menage at google.com
Wed Apr 23 08:37:45 PDT 2008


On Wed, Apr 23, 2008 at 8:17 AM, Cedric Le Goater <clg at 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 at 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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