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kprobes: fix wait_for_kprobe_optimizer()

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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.

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.

Only compile tested.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
This commit is contained in:
Tejun Heo 2012-12-21 17:57:00 -08:00
parent 7c99e0bf86
commit ad72b3bea7
1 changed files with 15 additions and 8 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

21
kernel/kprobes.c
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@ -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
/*
@ -552,7 +551,6 @@ 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);
}
@ -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 */