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    SubjectRe: [PATCH 1/5] spi: dw: fix possible race condition
    On Tue, Jul 17, 2018 at 5:23 PM, Alexandre Belloni
    <alexandre.belloni@bootlin.com> wrote:
    > It is possible to get an interrupt as soon as it is requested. dw_spi_irq
    > does spi_controller_get_devdata(master) and expects it to be different than
    > NULL. However, spi_controller_set_devdata() is called after request_irq(),
    > resulting in the following crash:
    >
    > CPU 0 Unable to handle kernel paging request at virtual address 00000030, epc == 8058e09c, ra == 8018ff90
    > [...]
    > Call Trace:
    > [<8058e09c>] dw_spi_irq+0x8/0x64
    > [<8018ff90>] __handle_irq_event_percpu+0x70/0x1d4
    > [<80190128>] handle_irq_event_percpu+0x34/0x8c
    > [<801901c4>] handle_irq_event+0x44/0x80
    > [<801951a8>] handle_level_irq+0xdc/0x194
    > [<8018f580>] generic_handle_irq+0x38/0x50
    > [<804c6924>] ocelot_irq_handler+0x104/0x1c0
    > [<8018f580>] generic_handle_irq+0x38/0x50
    > [<8075c1d8>] do_IRQ+0x18/0x24
    > [<804c4714>] plat_irq_dispatch+0xa4/0x150
    > [<80106ba8>] except_vec_vi_end+0xb8/0xc4
    > [<8075ba5c>] _raw_spin_unlock_irqrestore+0x14/0x20
    > [<801926c8>] __setup_irq+0x53c/0x8e0
    > [<80192e28>] request_threaded_irq+0xf4/0x1e8
    > [<8058ed18>] dw_spi_add_host+0x264/0x2c4
    > [<8058f2ec>] dw_spi_mmio_probe+0x258/0x27c
    > [<8051f4a4>] platform_drv_probe+0x58/0xbc
    > [<8051daa8>] driver_probe_device+0x308/0x40c
    > [<8051dc9c>] __driver_attach+0xf0/0xf8
    > [<8051b698>] bus_for_each_dev+0x78/0xcc
    > [<8051c2c0>] bus_add_driver+0x1b4/0x228
    > [<8051e840>] driver_register+0x84/0x154
    > [<801001d8>] do_one_initcall+0x54/0x1ac
    > [<80880e90>] kernel_init_freeable+0x1ec/0x2ac
    > [<80755310>] kernel_init+0x14/0x110
    > [<80106698>] ret_from_kernel_thread+0x14/0x1c
    > Code: 00000000 8ca40050 8c820008 <8c420030> 0000000f 3042003f 10400007 00000000 8ca20230
    >

    Good catch!

    Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

    > Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
    > ---
    > drivers/spi/spi-dw.c | 3 ++-
    > 1 file changed, 2 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
    > index f693bfe95ab9..a087464efdd7 100644
    > --- a/drivers/spi/spi-dw.c
    > +++ b/drivers/spi/spi-dw.c
    > @@ -485,6 +485,8 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
    > dws->dma_inited = 0;
    > dws->dma_addr = (dma_addr_t)(dws->paddr + DW_SPI_DR);
    >
    > + spi_controller_set_devdata(master, dws);
    > +
    > ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dev_name(dev),
    > master);
    > if (ret < 0) {
    > @@ -518,7 +520,6 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
    > }
    > }
    >
    > - spi_controller_set_devdata(master, dws);
    > ret = devm_spi_register_controller(dev, master);
    > if (ret) {
    > dev_err(&master->dev, "problem registering spi master\n");
    > --
    > 2.18.0
    >
    > --
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    --
    With Best Regards,
    Andy Shevchenko

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