spi: dw: fix possible race condition

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

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index f693bfe95ab9a1133e93a30b148f2b89a9499413..a087464efdd7592b68f27349b8ee693e247edaa9 100644 (file)
--- 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");