[PATCH 4.4 026/101] spi: dw: fix possible race condition

[Greg Kroah-Hartman]

[ 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@xxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 5688591e9cd3..61a951549eba 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -501,6 +501,8 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
 	snprintf(dws->name, sizeof(dws->name), "dw_spi%d", dws->bus_num);
 	spin_lock_init(&dws->buf_lock);
 
+	spi_master_set_devdata(master, dws);
+
 	ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dws->name, master);
 	if (ret < 0) {
 		dev_err(dev, "can not get IRQ\n");
@@ -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