[PATCH 3.5 36/88] spidev: fix hang when transfer_one_message fails

[Daniel Santos]

On 02/07/2014 05:22 AM, Luis Henriques wrote:
> 3.5.7.30 -stable review patch.  If anyone has any objections, please let me know.
>
> ------------------
>
> From: Daniel Santos <daniel.santos at pobox.com>
>
> commit e120cc0dcf2880a4c5c0a6cb27b655600a1cfa1d upstream.
>
> This corrects a problem in spi_pump_messages() that leads to an spi
> message hanging forever when a call to transfer_one_message() fails.
> This failure occurs in my MCP2210 driver when the cs_change bit is set
> on the last transfer in a message, an operation which the hardware does
> not support.
>
> Rationale
> Since the transfer_one_message() returns an int, we must presume that it
> may fail.  If transfer_one_message() should never fail, it should return
> void.  Thus, calls to transfer_one_message() should properly manage a
> failure.
>
> Fixes: ffbbdd21329f3 (spi: create a message queueing infrastructure)
> Signed-off-by: Daniel Santos <daniel.santos at pobox.com>
> Signed-off-by: Mark Brown <broonie at linaro.org>
> Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
> ---
>   drivers/spi/spi.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index 1041cb8..40f528b 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -574,7 +574,9 @@ static void spi_pump_messages(struct kthread_work *work)
>   	ret = master->transfer_one_message(master, master->cur_msg);
>   	if (ret) {
>   		dev_err(&master->dev,
> -			"failed to transfer one message from queue\n");
> +			"failed to transfer one message from queue: %d\n", ret);
> +		master->cur_msg->status = ret;
> +		spi_finalize_current_message(master);
>   		return;
>   	}
>   }

This isn't a good patch and is reverted by a later patch. I'm not sure 
what the protocol for this is, but either skip this patch or include the 
one that reverts it.

Daniel