Commit ad72b3be authored by Tejun Heo's avatar Tejun Heo
Browse files

kprobes: fix wait_for_kprobe_optimizer() 



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: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarMasami 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>
parent 7c99e0bf

kernel/kprobes.c

+15 −8
Original line number Diff line number Diff line
@@ -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 */

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