Commit 41682e03 authored Aug 24, 2012 by Marek Vasut Committed by Mark Brown Aug 27, 2012

mxs/spi: Fix misuse of init_completion



The init_completion() call does reinit not only the variable carrying
the flag that the completion finished, but also initialized the
waitqueue associated with the completion. On the contrary, the
INIT_COMPLETION() call only reinits the flag.

In case there was anything still stuck in the waitqueue, subsequent call
to init_completion() would be able to create possible race condition. This
patch uses the proper function and moves init_completion() into .probe() call
of the driver, to be issued only once.

Note that such scenario is impossible, since two threads can never enter the
mxs_spi_txrx_dma(), since whole this section is protected by mutex in SPI core.
This by no means allows this issue to exit though.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chris Ball <cjb@laptop.org>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

parent c895db0f

drivers/spi/spi-mxs.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -230,7 +230,7 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, int cs,
		return -EINVAL;
		}

		init_completion(&spi->c);
		INIT_COMPLETION(spi->c);

		if (*first)
		pio \|= BM_SSP_CTRL0_LOCK_CS;
		@@ -549,6 +549,8 @@ static int __devinit mxs_spi_probe(struct platform_device *pdev)
		ssp->devid = devid;
		ssp->dma_channel = dma_channel;

		init_completion(&spi->c);

		ret = devm_request_irq(&pdev->dev, irq_err, mxs_ssp_irq_handler, 0,
		DRIVER_NAME, ssp);
		if (ret)

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