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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.18 153/235] spi: dw: fix possible race condition
Date:   Mon, 24 Sep 2018 13:52:19 +0200
Message-Id: <20180924113120.644318048@linuxfoundation.org>
In-Reply-To: <20180924113103.999624566@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexandre Belloni <alexandre.belloni@bootlin.com>

[ 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 <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/spi/spi-dw.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -485,6 +485,8 @@ int dw_spi_add_host(struct device *dev,
 	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,
 		}
 	}
 
-	spi_controller_set_devdata(master, dws);
 	ret = devm_spi_register_controller(dev, master);
 	if (ret) {
 		dev_err(&master->dev, "problem registering spi master\n");