lkml.org 
[lkml]   [2012]   [Dec]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 10/25] kprobes: fix wait_for_kprobe_optimizer()
(2012/12/22 10:57), Tejun Heo wrote:
> wait_for_kprobe_optimizer() seems largely broken. It uses
> optimizer_comp which is never re-initialized, so
> wait_for_kprobe_optimizer() will never wait for anything once
> kprobe_optimizer() finishes all pending jobs for the first time.

Thank you for fixing that!
I must misunderstand that the DECLARE_COMPLETION() macro.

> Also, aside from completion, delayed_work_pending() is %false once
> kprobe_optimizer() starts execution and wait_for_kprobe_optimizer()
> won't wait for it.
>
> Reimplement it so that it flushes optimizing_work until
> [un]optimizing_lists are empty. Note that this also makes
> optimizing_work execute immediately if someone's waiting for it, which
> is the nicer behavior.

I think your enhancement is reasonable and GOOD for me.

Thanks again!

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>


>
> Only compile tested.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> ---
> Please let me know how this patch should be routed. I can take it
> through the workqueue tree if necessary.
>
> Thanks.
>
> kernel/kprobes.c | 23 +++++++++++++++--------
> 1 file changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 098f396..f230e81 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -471,7 +471,6 @@ static LIST_HEAD(unoptimizing_list);
>
> static void kprobe_optimizer(struct work_struct *work);
> static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
> -static DECLARE_COMPLETION(optimizer_comp);
> #define OPTIMIZE_DELAY 5
>
> /*
> @@ -552,8 +551,7 @@ static __kprobes void do_free_cleaned_kprobes(struct list_head *free_list)
> /* Start optimizer after OPTIMIZE_DELAY passed */
> static __kprobes void kick_kprobe_optimizer(void)
> {
> - if (!delayed_work_pending(&optimizing_work))
> - schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
> + schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
> }
>
> /* Kprobe jump optimizer */
> @@ -592,16 +590,25 @@ static __kprobes void kprobe_optimizer(struct work_struct *work)
> /* Step 5: Kick optimizer again if needed */
> if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
> kick_kprobe_optimizer();
> - else
> - /* Wake up all waiters */
> - complete_all(&optimizer_comp);
> }
>
> /* Wait for completing optimization and unoptimization */
> static __kprobes void wait_for_kprobe_optimizer(void)
> {
> - if (delayed_work_pending(&optimizing_work))
> - wait_for_completion(&optimizer_comp);
> + mutex_lock(&kprobe_mutex);
> +
> + while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
> + mutex_unlock(&kprobe_mutex);
> +
> + /* this will also make optimizing_work execute immmediately */
> + flush_delayed_work(&optimizing_work);
> + /* @optimizing_work might not have been queued yet, relax */
> + cpu_relax();
> +
> + mutex_lock(&kprobe_mutex);
> + }
> +
> + mutex_unlock(&kprobe_mutex);
> }
>
> /* Optimize kprobe if p is ready to be optimized */
>


--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com




\
 
 \ /
  Last update: 2012-12-25 05:01    [W:0.214 / U:2.388 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site