[PATCH 4.14 043/190] spi: dw: fix possible race condition

Greg Kroah-Hartman
2020-06-19T16:39:22Z

[ Upstream commit 66b19d762378785d1568b5650935205edfeb0503 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 cbdad3c4930f..5c16f7b17029 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -499,6 +499,8 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
dws->dma_addr = (dma_addr_t)(dws->paddr + DW_SPI_DR);
spin_lock_init(&dws->buf_lock);

+ spi_master_set_devdata(master, dws);
+
ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dev_name(dev),
master);
if (ret < 0) {
@@ -532,7 +534,6 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
}
}

- spi_master_set_devdata(master, dws);
ret = devm_spi_register_master(dev, master);
if (ret) {
dev_err(&master->dev, "problem registering spi master\n");
--
2.25.1