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SubjectRe: [thisops uV3 08/18] Taskstats: Use this_cpu_ops
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Hello Christoph,

On Tue, 2010-11-30 at 13:07 -0600, Christoph Lameter wrote:
> plain text document attachment (this_cpu_taskstats)
> Use this_cpu_inc_return in one place and avoid ugly __raw_get_cpu in another.
>
> Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
> Signed-off-by: Christoph Lameter <cl@linux.com>
>
> ---
> kernel/taskstats.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> Index: linux-2.6/kernel/taskstats.c
> ===================================================================
> --- linux-2.6.orig/kernel/taskstats.c 2010-11-30 10:06:35.000000000 -0600
> +++ linux-2.6/kernel/taskstats.c 2010-11-30 10:10:14.000000000 -0600
> @@ -89,8 +89,7 @@ static int prepare_reply(struct genl_inf
> return -ENOMEM;
>
> if (!info) {
> - int seq = get_cpu_var(taskstats_seqnum)++;
> - put_cpu_var(taskstats_seqnum);
> + int seq = this_cpu_inc_return(taskstats_seqnum);

Hmmm, wouldn't seq now always be one more than before?

I think that "seq = get_cpu_var(taskstats_seqnum)++" first assigns
taskstats_seqnum to seq and then increases the value in contrast to
this_cpu_inc_return() that returns the already increased value, correct?

Maybe that does not hurt here, Balbir?

> reply = genlmsg_put(skb, 0, seq, &family, 0, cmd);
> } else
> @@ -581,7 +580,7 @@ void taskstats_exit(struct task_struct *
> fill_tgid_exit(tsk);
> }
>
> - listeners = &__raw_get_cpu_var(listener_array);
> + listeners = __this_cpu_ptr(listener_array);
> if (list_empty(&listeners->list))
> return;
>
>




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