Re: [RFA][PATCH 21/27] MIPS: ftrace: Remove check of obsolete variable function_trace_stop

[Steven Rostedt <rostedt@goodmis.org>]

On Thu, 26 Jun 2014 12:52:42 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> Nothing sets function_trace_stop to disable function tracing anymore.
> Remove the check for it in the arch code.
> 
> [ Please test this on your arch ]
> 

Bah! I forgot to add you to the Cc of this email :-p

Anyway,

From the cover letter, you were not Cc'd on.

Anyway, as there is no more reason to set function_trace_stop it is time
to remove it. Unfortunately it's in several archs in assembly. Most of
the assembly looks rather straight forward and I removed them myself.
But I was only able to compile test them (for archs: arm64, metag, and
microblaze I do not have my cross tools set up for them and did not
even compile test it). But I would really love it if people can
download their patch and test it out. You only need the patches that go
against your arch and to really test it, also include the patch titled: 

 ftrace: Remove check for HAVE_FUNCTION_TRACE_MCOUNT_TEST

Otherwise your arch patch will call the list op that still does the
check. That is, if you want to test suspend and resume on your arch.

As you may see, there are patches to the ftrace infrastructure that
depend on the arch patches being implemented. I removed the
functionality from the infrastructure, then removed it from the archs,
and then finally removed the existence of the function_trace_stop
variable, which would cause the archs to fail to compile if that were
to go first.

If you can test your arch and give me your acked-by, I would appreciate
it. Otherwise, if you need this to go through your tree, I would ask you
to set up a dedicated branch that I can pull from to keep this order
intact.

-- Steve


> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
>  arch/mips/Kconfig         | 1 -
>  arch/mips/kernel/mcount.S | 7 -------
>  2 files changed, 8 deletions(-)
> 
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 7a469acee33c..9ca52987fcd5 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -15,7 +15,6 @@ config MIPS
>  	select HAVE_BPF_JIT if !CPU_MICROMIPS
>  	select ARCH_HAVE_CUSTOM_GPIO_H
>  	select HAVE_FUNCTION_TRACER
> -	select HAVE_FUNCTION_TRACE_MCOUNT_TEST
>  	select HAVE_DYNAMIC_FTRACE
>  	select HAVE_FTRACE_MCOUNT_RECORD
>  	select HAVE_C_RECORDMCOUNT
> diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S
> index 539b6294b613..00940d1d5c4f 100644
> --- a/arch/mips/kernel/mcount.S
> +++ b/arch/mips/kernel/mcount.S
> @@ -74,10 +74,6 @@ _mcount:
>  #endif
>  
>  	/* When tracing is activated, it calls ftrace_caller+8 (aka here) */
> -	lw	t1, function_trace_stop
> -	bnez	t1, ftrace_stub
> -	 nop
> -
>  	MCOUNT_SAVE_REGS
>  #ifdef KBUILD_MCOUNT_RA_ADDRESS
>  	PTR_S	MCOUNT_RA_ADDRESS_REG, PT_R12(sp)
> @@ -105,9 +101,6 @@ ftrace_stub:
>  #else	/* ! CONFIG_DYNAMIC_FTRACE */
>  
>  NESTED(_mcount, PT_SIZE, ra)
> -	lw	t1, function_trace_stop
> -	bnez	t1, ftrace_stub
> -	 nop
>  	PTR_LA	t1, ftrace_stub
>  	PTR_L	t2, ftrace_trace_function /* Prepare t2 for (1) */
>  	bne	t1, t2, static_trace