Hi Mark,
On Thu, Jan 30, 2014 at 11:38 PM, Mark Brown <[email protected]> wrote:
> From: Mark Brown <[email protected]>
>
> Don't wait indefinitely for transfers to complete but time out after 10ms
> more than we expect the transfer to take on the wire.
>
> Signed-off-by: Mark Brown <[email protected]>
> ---
> drivers/spi/spi.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index 7f23cf9afa79..1826a50c2aaf 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -710,6 +710,7 @@ static int spi_transfer_one_message(struct spi_master
> *master,
> bool cur_cs = true;
> bool keep_cs = false;
> int ret = 0;
> + int ms = 1;
>
> spi_set_cs(msg->spi, true);
>
> @@ -727,7 +728,16 @@ static int spi_transfer_one_message(struct spi_master
> *master,
>
> if (ret > 0) {
> ret = 0;
> - wait_for_completion(&master->xfer_completion);
> + ms = xfer->len * 8 * 1000 / xfer->speed_hz;
> + ms += 10; /* some tolerance */
> +
> + ms =
> wait_for_completion_timeout(&master->xfer_completion,
> +
> msecs_to_jiffies(ms));
> + }
> +
> + if (ms == 0) {
> + dev_err(&msg->spi->dev, "SPI transfer timed out\n");
> + msg->status = -ETIMEDOUT;
> }
>
> trace_spi_transfer_stop(msg, xfer);
What if it still completes in the driver a little bit later? The
driver will also call
spi_finalize_current_message(), and we'll get a NULL pointer dereference
as master->cur_msg is now NULL.
So I think we need a check like (whitespace damaged) below:
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -829,6 +829,9 @@ void spi_finalize_current_message(struct spi_master *master)
queue_kthread_work(&master->kworker, &master->pump_messages);
spin_unlock_irqrestore(&master->queue_lock, flags);
+ if (!mesg)
+ return NULL;
+
if (master->cur_msg_prepared && master->unprepare_message) {
ret = master->unprepare_message(master, mesg);
if (ret) {
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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