linux-kernel - Re: [PATCH v4 5/5] soc/tegra: pmc: Rate-limit error message about failed to acquire of reset

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Date:   Thu, 25 Mar 2021 15:42:15 +0100
From:   Thierry Reding <thierry.reding@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Jonathan Hunter <jonathanh@...dia.com>,
        Peter Geis <pgwipeout@...il.com>,
        Matt Merhar <mattmerhar@...tonmail.com>,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 5/5] soc/tegra: pmc: Rate-limit error message about
 failed to acquire of reset

On Tue, Mar 02, 2021 at 03:25:02PM +0300, Dmitry Osipenko wrote:
> PMC domain could be easily bombarded with the enable requests if there is
> a problem in regards to acquiring reset control of a domain and kernel
> log will be flooded with the error message in this case. Hence rate-limit
> the message in order to prevent missing other important messages.
> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/soc/tegra/pmc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
> index bf29ea22480a..84ab27d85d92 100644
> --- a/drivers/soc/tegra/pmc.c
> +++ b/drivers/soc/tegra/pmc.c
> @@ -868,8 +868,8 @@ static int tegra_genpd_power_off(struct generic_pm_domain *domain)
>  
>  	err = reset_control_acquire(pg->reset);
>  	if (err < 0) {
> -		dev_err(dev, "failed to acquire resets for PM domain %s: %d\n",
> -			pg->genpd.name, err);
> +		dev_err_ratelimited(dev, "failed to acquire resets for PM domain %s: %d\n",
> +				    pg->genpd.name, err);

That doesn't look right. This is a serious error condition that
shouldn't happen at all. Ever. If this shows up even once we've got a
serious bug somewhere and we need to fix it rather than "downplay" it
by ratelimiting these errors.

What's the exact use-case where you see this?

Thierry

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