[PATCH] spi/mxs: Fix device remove function

[Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>]

The call sequence spi_alloc_master/spi_register_master/spi_unregister_master
is complete; it reduces the device reference count to zero, which results in
device memory being freed. The remove function accesses the freed memory after
the call to spi_unregister_master(), _and_ it calls spi_master_put on the freed
memory.

Acquire a reference to the SPI master device and release it after cleanup is
complete (with the existing spi_master_put) to solve the problem.

Also, the device subsystem ensures that the remove function is only called once,
and resets device driver data to NULL. Remove the unnecessaary calls to
platform_set_drvdata().

Cc: Marek Vasut <marex-ynQEQJNshbs@public.gmane.org>
Signed-off-by: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
---
Applies to -next (as of 8/24/12).

 drivers/spi/spi-mxs.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/spi/spi-mxs.c b/drivers/spi/spi-mxs.c
index 130a436..cb189b7 100644
--- a/drivers/spi/spi-mxs.c
+++ b/drivers/spi/spi-mxs.c
@@ -582,7 +582,6 @@ static int __devinit mxs_spi_probe(struct platform_device *pdev)
 	return 0;
 
 out_free_dma:
-	platform_set_drvdata(pdev, NULL);
 	dma_release_channel(ssp->dmach);
 	clk_disable_unprepare(ssp->clk);
 out_master_free:
@@ -596,14 +595,12 @@ static int __devexit mxs_spi_remove(struct platform_device *pdev)
 	struct mxs_spi *spi;
 	struct mxs_ssp *ssp;
 
-	master = platform_get_drvdata(pdev);
+	master = spi_master_get(platform_get_drvdata(pdev));
 	spi = spi_master_get_devdata(master);
 	ssp = &spi->ssp;
 
 	spi_unregister_master(master);
 
-	platform_set_drvdata(pdev, NULL);
-
 	dma_release_channel(ssp->dmach);
 
 	clk_disable_unprepare(ssp->clk);
-- 
1.7.9.7


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