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_WAITQUEUE() 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 <ma...@denx.de>
Cc: Chris Ball <c...@laptop.org>
Cc: Shawn Guo <shawn....@linaro.org>
Cc: Mark Brown <broo...@opensource.wolfsonmicro.com>
Cc: Fabio Estevam <fabio.este...@freescale.com>
---
drivers/spi/spi-mxs.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
V2: Update the patch description and snap a whip over myself for being lazy to
write one in the first place!
diff --git a/drivers/spi/spi-mxs.c b/drivers/spi/spi-mxs.c
index 331f600..c965cc6 100644
--- a/drivers/spi/spi-mxs.c
+++ b/drivers/spi/spi-mxs.c
@@ -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;
@@ -560,6 +560,8 @@ 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)
--
1.7.10.4
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