linux-kernel - Re: [PATCH] ftrace: disable preemption when recursion locked in arch/s390/kernel/ftrace.c

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Date:   Wed, 8 Dec 2021 10:20:08 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Jerome Marchand" <jmarchan@...hat.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        王贇 <yun.wang@...ux.alibaba.com>,
        linux-kernel@...r.kernel.org, Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        linux-s390@...r.kernel.org
Subject: Re: [PATCH] ftrace: disable preemption when recursion locked in
 arch/s390/kernel/ftrace.c


This really needs to go through the s390 tree.

-- Steve


On Wed,  8 Dec 2021 16:15:03 +0100
"Jerome Marchand" <jmarchan@...hat.com> wrote:

> It looks like commit ce5e48036c9e76a2 ("ftrace: disable preemption
> when recursion locked") missed a spot in kprobe_ftrace_handler() in
> arch/s390/kernel/ftrace.c.
> Removes the superfluous preempt_disable/enable_notrace() there too.
> 
> Fixes: ce5e48036c9e76a2 ("ftrace: disable preemption when recursion locked")
> Signed-off-by: Jerome Marchand <jmarchan@...hat.com>
> ---
>  arch/s390/kernel/ftrace.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
> index 5510c7d10ddc..21d62d8b6b9a 100644
> --- a/arch/s390/kernel/ftrace.c
> +++ b/arch/s390/kernel/ftrace.c
> @@ -290,7 +290,6 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
>  		return;
>  
>  	regs = ftrace_get_regs(fregs);
> -	preempt_disable_notrace();
>  	p = get_kprobe((kprobe_opcode_t *)ip);
>  	if (unlikely(!p) || kprobe_disabled(p))
>  		goto out;
> @@ -318,7 +317,6 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
>  	}
>  	__this_cpu_write(current_kprobe, NULL);
>  out:
> -	preempt_enable_notrace();
>  	ftrace_test_recursion_unlock(bit);
>  }
>  NOKPROBE_SYMBOL(kprobe_ftrace_handler);