linux-kernel - Re: [PATCH v2 1/3] spi: spi-fsl-dspi: Fix external abort on interrupt in exit paths

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Date:   Mon, 15 Jun 2020 12:23:41 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Marc Kleine-Budde <mkl@...gutronix.de>
Cc:     Krzysztof Kozlowski <krzk@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vladimir Oltean <vladimir.oltean@....com>,
        linux-spi <linux-spi@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Wolfram Sang <wsa@...nel.org>, stable@...r.kernel.org,
        Pengutronix Kernel Team <kernel@...gutronix.de>
Subject: Re: [PATCH v2 1/3] spi: spi-fsl-dspi: Fix external abort on interrupt
 in exit paths

On Mon, 15 Jun 2020 at 11:18, Marc Kleine-Budde <mkl@...gutronix.de> wrote:
>
> On 6/15/20 10:07 AM, Krzysztof Kozlowski wrote:
> > If interrupt comes late, during probe error path or device remove (could
> > be triggered with CONFIG_DEBUG_SHIRQ), the interrupt handler
> > dspi_interrupt() will access registers with the clock being disabled.  This
> > leads to external abort on non-linefetch on Toradex Colibri VF50 module
> > (with Vybrid VF5xx):
> >
> >     $ echo 4002d000.spi > /sys/devices/platform/soc/40000000.bus/4002d000.spi/driver/unbind
> >
> >     Unhandled fault: external abort on non-linefetch (0x1008) at 0x8887f02c
> >     Internal error: : 1008 [#1] ARM
> >     CPU: 0 PID: 136 Comm: sh Not tainted 5.7.0-next-20200610-00009-g5c913fa0f9c5-dirty #74
> >     Hardware name: Freescale Vybrid VF5xx/VF6xx (Device Tree)
> >       (regmap_mmio_read32le) from [<8061885c>] (regmap_mmio_read+0x48/0x68)
> >       (regmap_mmio_read) from [<8060e3b8>] (_regmap_bus_reg_read+0x24/0x28)
> >       (_regmap_bus_reg_read) from [<80611c50>] (_regmap_read+0x70/0x1c0)
> >       (_regmap_read) from [<80611dec>] (regmap_read+0x4c/0x6c)
> >       (regmap_read) from [<80678ca0>] (dspi_interrupt+0x3c/0xa8)
> >       (dspi_interrupt) from [<8017acec>] (free_irq+0x26c/0x3cc)
> >       (free_irq) from [<8017dcec>] (devm_irq_release+0x1c/0x20)
> >       (devm_irq_release) from [<805f98ec>] (release_nodes+0x1e4/0x298)
> >       (release_nodes) from [<805f9ac8>] (devres_release_all+0x40/0x60)
> >       (devres_release_all) from [<805f5134>] (device_release_driver_internal+0x108/0x1ac)
> >       (device_release_driver_internal) from [<805f521c>] (device_driver_detach+0x20/0x24)
> >
> > Fixes: 349ad66c0ab0 ("spi:Add Freescale DSPI driver for Vybrid VF610 platform")
> > Cc: <stable@...r.kernel.org>
> > Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
> >
> > ---
> >
> > This is an follow up of my other patch for I2C IMX driver [1]. Let's fix the
> > issues consistently.
> >
> > [1] https://lore.kernel.org/lkml/1592130544-19759-2-git-send-email-krzk@kernel.org/T/#u
> >
> > Changes since v1:
> > 1. Disable the IRQ instead of using non-devm interface.
> > ---
> >  drivers/spi/spi-fsl-dspi.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
> > index 58190c94561f..023e05c53b85 100644
> > --- a/drivers/spi/spi-fsl-dspi.c
> > +++ b/drivers/spi/spi-fsl-dspi.c
> > @@ -1400,7 +1400,7 @@ static int dspi_probe(struct platform_device *pdev)
> >               ret = dspi_request_dma(dspi, res->start);
> >               if (ret < 0) {
> >                       dev_err(&pdev->dev, "can't get dma channels\n");
> > -                     goto out_clk_put;
> > +                     goto disable_irq;
> >               }
> >       }
> >
> > @@ -1415,11 +1415,14 @@ static int dspi_probe(struct platform_device *pdev)
> >       ret = spi_register_controller(ctlr);
> >       if (ret != 0) {
> >               dev_err(&pdev->dev, "Problem registering DSPI ctlr\n");
> > -             goto out_clk_put;
> > +             goto disable_irq;
> >       }
> >
> >       return ret;
> >
> > +disable_irq:
> > +     if (dspi->irq > 0)
> > +             disable_irq(dspi->irq);
> >  out_clk_put:
> >       clk_disable_unprepare(dspi->clk);
> >  out_ctlr_put:
> > @@ -1435,6 +1438,8 @@ static int dspi_remove(struct platform_device *pdev)
> >
> >       /* Disconnect from the SPI framework */
> >       dspi_release_dma(dspi);
> > +     if (dspi->irq > 0)
> > +             disable_irq(dspi->irq);
>
> What happens, if you re-bind the driver?
> Is the IRQ still working?
> Who is taking care of calling the enable_irq() again?
> What happens, if you really have a shared IRQ line?
> Is the IRQ disabled for all other devices on the same IRQ line?
>

Yup, devm is completely broken for shared IRQs.

> >       clk_disable_unprepare(dspi->clk);
> >       spi_unregister_controller(dspi->ctlr);
> >
> >
> Marc
>
> --
> Pengutronix e.K.                 | Marc Kleine-Budde           |
> Embedded Linux                   | https://www.pengutronix.de  |
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