linux-kernel - Re: [RFC] opp: Fixup release of clock when using set/put clkname

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Message-ID: <20200414071823.jdhkprtkizyeua23@vireshk-i7>
Date:   Tue, 14 Apr 2020 12:48:23 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rajendra Nayak <rnayak@...eaurora.org>
Cc:     sboyd@...nel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC] opp: Fixup release of clock when using set/put clkname

On 14-04-20, 12:45, Rajendra Nayak wrote:
> Fixup dev_pm_opp_put_clkname() to check for a valid clock pointer
> before it does a clk_put, since its likely that
> _opp_table_kref_release() has already done a clk_put. Also fixup

kref release is the last thing that happens on the table, it can't get
called after dev_pm_opp_put_clkname().

> _opp_table_kref_release() to set the clock pointer to ERR_PTR(-EINVAL)
> after its done doing a clk_put so dev_pm_opp_put_clkname() can then
> catch it.
> 
> Signed-off-by: Rajendra Nayak <rnayak@...eaurora.org>
> ---
>  drivers/opp/core.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index e4f01e7..6d064a8 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1061,8 +1061,10 @@ static void _opp_table_kref_release(struct kref *kref)
>  	_of_clear_opp_table(opp_table);
>  
>  	/* Release clk */
> -	if (!IS_ERR(opp_table->clk))
> +	if (!IS_ERR(opp_table->clk)) {
>  		clk_put(opp_table->clk);
> +		opp_table->clk = ERR_PTR(-EINVAL);
> +	}
>  
>  	WARN_ON(!list_empty(&opp_table->opp_list));
>  
> @@ -1744,8 +1746,10 @@ void dev_pm_opp_put_clkname(struct opp_table *opp_table)
>  	/* Make sure there are no concurrent readers while updating opp_table */
>  	WARN_ON(!list_empty(&opp_table->opp_list));
>  
> -	clk_put(opp_table->clk);
> -	opp_table->clk = ERR_PTR(-EINVAL);
> +	if (!IS_ERR(opp_table->clk)) {
> +		clk_put(opp_table->clk);
> +		opp_table->clk = ERR_PTR(-EINVAL);
> +	}
>  
>  	dev_pm_opp_put_opp_table(opp_table);
>  }
> -- 
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation

-- 
viresh