linux-kernel - Re: [PATCH 2/2] spi: spi-fsl-dspi: Initialize completion before possible interrupt

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Date:   Sun, 14 Jun 2020 14:14:15 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Mark Brown <broonie@...nel.org>,
        Vladimir Oltean <vladimir.oltean@....com>,
        linux-spi <linux-spi@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Wolfram Sang <wsa@...nel.org>, stable@...r.kernel.org
Subject: Re: [PATCH 2/2] spi: spi-fsl-dspi: Initialize completion before
 possible interrupt

On Sun, 14 Jun 2020 at 13:56, Krzysztof Kozlowski <krzk@...nel.org> wrote:
>
> If interrupt fires early, the dspi_interrupt() could complete
> (dspi->xfer_done) before its initialization happens.
>
> Fixes: 4f5ee75ea171 ("spi: spi-fsl-dspi: Replace interruptible wait queue with a simple completion")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
> ---

Why would an interrupt fire before spi_register_controller, therefore
before dspi_transfer_one_message could get called?
Is this master or slave mode?

>  drivers/spi/spi-fsl-dspi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
> index 57e7a626ba00..efb63ed9fd86 100644
> --- a/drivers/spi/spi-fsl-dspi.c
> +++ b/drivers/spi/spi-fsl-dspi.c
> @@ -1385,6 +1385,8 @@ static int dspi_probe(struct platform_device *pdev)
>                 goto poll_mode;
>         }
>
> +       init_completion(&dspi->xfer_done);
> +
>         ret = request_threaded_irq(dspi->irq, dspi_interrupt, NULL,
>                                    IRQF_SHARED, pdev->name, dspi);
>         if (ret < 0) {
> @@ -1392,8 +1394,6 @@ static int dspi_probe(struct platform_device *pdev)
>                 goto out_clk_put;
>         }
>
> -       init_completion(&dspi->xfer_done);
> -
>  poll_mode:
>
>         if (dspi->devtype_data->trans_mode == DSPI_DMA_MODE) {
> --
> 2.7.4
>