linux-kernel - Re: [PATCH v2 1/1] mmc: host: meson-gx-mmc: fix possible deadlock condition for preempt

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Message-ID: <7hwo0dmnbt.fsf@baylibre.com>
Date:   Mon, 28 Sep 2020 17:35:50 -0700
From:   Kevin Hilman <khilman@...libre.com>
To:     Brad Harper <bjharper@...il.com>,
        linux-amlogic@...ts.infradead.org, linux-mmc@...r.kernel.org
Cc:     linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Brad Harper <bjharper@...il.com>
Subject: Re: [PATCH v2 1/1] mmc: host: meson-gx-mmc: fix possible deadlock condition for preempt_rt

Brad Harper <bjharper@...il.com> writes:

> ---
>  drivers/mmc/host/meson-gx-mmc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)


This patch still needs changelog summarizing the problem and what is
being fixed by the patch.  Most of what's in the cover letter belongs
here.

The cover letter can be used to describe the history/background that you
don't want in the patch itself.  Alternatviely, you could include that
information in the a single patch email also because everything after
the "---" line does not end up in git history.

> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index 08a3b1c05..3ba8f988d 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -146,6 +146,7 @@ struct sd_emmc_desc {
>  };
>  
>  struct meson_host {
> +	spinlock_t		lock;
>  	struct	device		*dev;
>  	struct	meson_mmc_data *data;
>  	struct	mmc_host	*mmc;
> @@ -1051,6 +1052,7 @@ static int meson_mmc_probe(struct platform_device *pdev)
>  	host->mmc = mmc;
>  	host->dev = &pdev->dev;
>  	dev_set_drvdata(&pdev->dev, host);
> +	spin_lock_init(&host->lock);

I'm confused about what this lock is intended to do.  You init it here,
but it's never used anywhere.  

>  	/* The G12A SDIO Controller needs an SRAM bounce buffer */
>  	host->dram_access_quirk = device_property_read_bool(&pdev->dev,
> @@ -1139,7 +1141,7 @@ static int meson_mmc_probe(struct platform_device *pdev)
>  	       host->regs + SD_EMMC_IRQ_EN);
>  
>  	ret = request_threaded_irq(host->irq, meson_mmc_irq,
> -				   meson_mmc_irq_thread, IRQF_ONESHOT,
> +				   meson_mmc_irq_thread, 0,
>  				   dev_name(&pdev->dev), host);
>  	if (ret)
>  		goto err_init_clk;

Kevin