[4.9,029/128] spi: dw: fix possible race condition

Message ID 20200619141621.706156204@linuxfoundation.org
State New
Headers show
Series
  • Untitled series #28329
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Commit Message

Greg Kroah-Hartman June 19, 2020, 2:32 p.m.
[ 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(-)

Patch

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index babf0a337e96..be3ab4006313 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -500,6 +500,8 @@  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");
@@ -531,7 +533,6 @@  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");