linux-kernel - Re: [PATCH 06/13] jump label v9: move ftrace_dyn_arch

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Date:	Fri, 18 Jun 2010 23:24:38 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Jason Baron <jbaron@...hat.com>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu,
	mathieu.desnoyers@...ymtl.ca, hpa@...or.com, tglx@...utronix.de,
	andi@...stfloor.org, roland@...hat.com, rth@...hat.com,
	mhiramat@...hat.com, fweisbec@...il.com, avi@...hat.com,
	davem@...emloft.net, vgoyal@...hat.com, sam@...nborg.org,
	Abhishek Sagar <sagar.abhishek@...il.com>
Subject: Re: [PATCH 06/13] jump label v9: move ftrace_dyn_arch_init to
 common code

On Wed, 2010-06-09 at 17:39 -0400, Jason Baron wrote:
> Move Steve's code for finding the best 5-byte no-op from ftrace.c to alternative.c.
> The idea is that other consumers (in this case jump label) want to make use of
> that code. I've created a global: 'char ideal_nop[5]', that is setup during
> setup_arch that can be used.
> 
> Signed-off-by: Jason Baron <jbaron@...hat.com>

> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 0d88ce9..1a1cc47 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -2749,20 +2749,9 @@ extern unsigned long __stop_mcount_loc[];
>  
>  void __init ftrace_init(void)
>  {
> -	unsigned long count, addr, flags;
> +	unsigned long count;
>  	int ret;
>  
> -	/* Keep the ftrace pointer to the stub */
> -	addr = (unsigned long)ftrace_stub;
> -
> -	local_irq_save(flags);
> -	ftrace_dyn_arch_init(&addr);
> -	local_irq_restore(flags);
> -
> -	/* ftrace_dyn_arch_init places the return code in addr */
> -	if (addr)
> -		goto failed;
> -
>  	count = __stop_mcount_loc - __start_mcount_loc;
>  
>  	ret = ftrace_dyn_table_alloc(count);

Um, you just removed the ftrace arch specific setup call for dynamic
ftrace. Although, I'm thinking this may not be needed since all archs
currently have just a stub. With the exception of ARM which seems to
call a "ftrace_mcount_set()" that git grep can not find.

Thus, if you remove this, then remove it from all archs.

-- Steve


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