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Message-ID: <20090713134158.GD5051@balbir.in.ibm.com>
Date: Mon, 13 Jul 2009 19:11:58 +0530
From: Balbir Singh <balbir@...ux.vnet.ibm.com>
To: Nikanth Karthikesan <knikanth@...e.de>
Cc: Paul Menage <menage@...gle.com>, lizf@...fujitsu.com,
linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] taskstats: Fix CGROUPSTATS_TYPE_CGROUP_STATS
having same value as TASKSTATS_TYPE_PID
* Nikanth Karthikesan <knikanth@...e.de> [2009-07-13 18:31:12]:
> Hi
>
> Currently we never get message from kernel to userspace of type
> TASKSTATS_TYPE_PID. Otherwise this could have been spotted earlier.
>
> I was trying to add a new taskstat command that would return response of type
> TASKSTATS_TYPE_PID.
>
> Having the same values would restrict one not to use the same netlink socket
> for a command that would return response of type TASKSTATS_TYPE_PID and the
> CGROUPSTATS_CMD_GET command.
>
> Should we fix it by using values after __TASKSTATS_TYPE_MAX.
>
> Changing this now might break pre-built binaries. Or is this intended, and the
> application is not supposed to use CGROUPSTATS and TASKSTATS on the same
> socket?
>
Ideally they are supposed to be on different sockets, but nothing
really is hard and fast in terms of rules.
> Thanks
> Nikanth
>
> Currently we never get message from kernel to userspace of type
> TASKSTATS_TYPE_PID. Otherwise this could have been spotted earlier. Having the
> values in the same range would restrict one not to use the same netlink socket
> for a command that would return response of type TASKSTATS_TYPE_PID and the
> CGROUPSTATS_CMD_GET command. Fix it by using values after
> __TASKSTATS_TYPE_MAX.
>
> Signed-off-by: Nikanth Karthikesan <knikanth@...e.de>
>
> ---
>
>
> diff --git a/include/linux/cgroupstats.h b/include/linux/cgroupstats.h
> index 3753c33..87b31f0 100644
> --- a/include/linux/cgroupstats.h
> +++ b/include/linux/cgroupstats.h
> @@ -53,7 +53,7 @@ enum {
> #define CGROUPSTATS_CMD_MAX (__CGROUPSTATS_CMD_MAX - 1)
>
> enum {
> - CGROUPSTATS_TYPE_UNSPEC = 0, /* Reserved */
> + CGROUPSTATS_TYPE_UNSPEC = __TASKSTATS_TYPE_MAX, /* Reserved */
> CGROUPSTATS_TYPE_CGROUP_STATS, /* contains name + stats */
> __CGROUPSTATS_TYPE_MAX,
> };
>
This seems like the correct fix
Reviewed-by: Balbir Singh <balbir@...ux.vnet.ibm.com>
--
Balbir
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