LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Marc Zyngier <marc.zyngier@arm.com>
To: Julien Thierry <julien.thierry@arm.com>,
	linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, Mark Rutland <mark.rutland@arm.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] clocksource/arm_arch_timer: Don't trace count reader functions
Date: Fri, 24 May 2019 10:53:31 +0100	[thread overview]
Message-ID: <9adf92c2-b7a5-00a3-ff09-58484d9bb9db@arm.com> (raw)
In-Reply-To: <1558689025-50679-1-git-send-email-julien.thierry@arm.com>

On 24/05/2019 10:10, Julien Thierry wrote:
> With v5.2-rc1, The ftrace functions_graph tracer locks up whenever it is
> enabled on arm64.
> 
> Since commit 0ea415390cd3 ("clocksource/arm_arch_timer: Use
> arch_timer_read_counter to access stable counters") a function pointer
> is consistently used to read the counter instead of potentially
> referencing an inlinable function.
> 
> The graph tacers relies on accessing the timer counters to compute the

nit: tracers

> time spent in functions which causes the lockup when attempting to trace
> these code paths.
> 
> Annontate the arm arch timer counter accessors as notrace.

nit: Annotate

> 
> Fixes: 0ea415390cd3 ("clocksource/arm_arch_timer: Use
>        arch_timer_read_counter to access stable counters")
> Signed-off-by: Julien Thierry <julien.thierry@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> ---
>  drivers/clocksource/arm_arch_timer.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index b2a951a..5c69c9a 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -149,22 +149,22 @@ u32 arch_timer_reg_read(int access, enum arch_timer_reg reg,
>  	return val;
>  }
>  
> -static u64 arch_counter_get_cntpct_stable(void)
> +static notrace u64 arch_counter_get_cntpct_stable(void)
>  {
>  	return __arch_counter_get_cntpct_stable();
>  }
>  
> -static u64 arch_counter_get_cntpct(void)
> +static notrace u64 arch_counter_get_cntpct(void)
>  {
>  	return __arch_counter_get_cntpct();
>  }
>  
> -static u64 arch_counter_get_cntvct_stable(void)
> +static notrace u64 arch_counter_get_cntvct_stable(void)
>  {
>  	return __arch_counter_get_cntvct_stable();
>  }
>  
> -static u64 arch_counter_get_cntvct(void)
> +static notrace u64 arch_counter_get_cntvct(void)
>  {
>  	return __arch_counter_get_cntvct();
>  }
> 

Well spotted, thanks Julien.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

Daniel, can you please pick this up for the next batch of clocksource fixes?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

  reply	other threads:[~2019-05-24  9:53 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-24  9:10 Julien Thierry
2019-05-24  9:53 ` Marc Zyngier [this message]
2019-05-24 10:42   ` Daniel Lezcano
2019-05-24 13:36 ` Steven Rostedt

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=9adf92c2-b7a5-00a3-ff09-58484d9bb9db@arm.com \
    --to=marc.zyngier@arm.com \
    --cc=daniel.lezcano@linaro.org \
    --cc=julien.thierry@arm.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    --subject='Re: [PATCH] clocksource/arm_arch_timer: Don'\''t trace count reader functions' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).