Re: [PATCH] spi: davinci: fix spurious i/o error

From: Sekhar Nori
Date: Tue Nov 24 2015 - 07:28:00 EST


On Tuesday 24 November 2015 04:04 PM, Sekhar Nori wrote:
> davinci_spi_bufs() uses wait_for_completion_interruptible()
> without bothering to handle -ERESTARTSYS. Due to this,
> sometime, it returns prematurely when a signal is received.
> Since the return value is never checked, userspace eventually
> receives a spurious -EIO.
>
> To fix this, use un-interruptible wait_for_completion_timeout().
>
> Signed-off-by: Sekhar Nori <nsekhar@xxxxxx>
> ---
> drivers/spi/spi-davinci.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
> index 7d3af3eacf57..38026aa1afd7 100644
> --- a/drivers/spi/spi-davinci.c
> +++ b/drivers/spi/spi-davinci.c
> @@ -703,7 +703,10 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t)
>
> /* Wait for the transfer to complete */
> if (spicfg->io_type != SPI_IO_TYPE_POLL) {
> - wait_for_completion_interruptible(&(dspi->done));
> + if (wait_for_completion_timeout(&dspi->done, HZ) == 0) {
> + dev_err(&spi->dev, "spi transfer timeout\n");
> + return -ETIMEDOUT;

Grygorii pointed out offline that this does not recover correctly in DMA
case. I will fix and send a v2.

Thanks,
Sekhar
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