linux-kernel - Re: [PATCH 1/3] ftrace: prevent freeing of all failed updates

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Message-ID: <Pine.LNX.4.58.0806021401340.10366@gandalf.stny.rr.com>
Date:	Mon, 2 Jun 2008 14:02:30 -0400 (EDT)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Abhishek Sagar <sagar.abhishek@...il.com>
cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] ftrace: prevent freeing of all failed updates



On Sun, 1 Jun 2008, Abhishek Sagar wrote:
5B> @@ -611,18 +612,33 @@ static int __ftrace_update_code(void *ignore)
>
>  	/* No locks needed, the machine is stopped! */
>  	for (i = 0; i < FTRACE_HASHSIZE; i++) {
> -		if (hlist_empty(&ftrace_hash[i]))
> -			continue;
> +		/* all CPUS are stopped, we are safe to modify code */
> +		hlist_for_each_entry_safe(p, t, n, &ftrace_hash[i], node) {
> +			/* Skip over failed records which have not been
> +			 * freed. */
> +			if (p->flags & FTRACE_FL_FAILED)
> +				continue;
>
> -		head = ftrace_hash[i];
> -		INIT_HLIST_HEAD(&ftrace_hash[i]);
> +			/* Unconverted records are always at the head of the
> +			 * hash bucket. Once we encounter a converted record,
> +			 * simply skip over to the next bucket. Saves ftraced
> +			 * some processor cycles (ftrace does its bid for
> +			 * global warming :-p ). */
> +			if (p->flags & (FTRACE_FL_CONVERTED))
> +				break;

If we unload a module and reload it, will it ever get converted again?

-- Steve
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