3.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Simon Lindgren <simon@xxxxxxxxxx>
commit 6721f28a26efd6368497abbdef5dcfc59608d899 upstream.
There is a race condition in at91_do_twi_xfer when signals arrive.
If a signal is recieved while waiting for a transfer to complete
wait_for_completion_interruptible_timeout() will return -ERESTARTSYS.
This is not handled correctly resulting in interrupts still being
enabled and a transfer being in flight when we return.
Symptoms include a range of oopses and bus lockups. Oopses can happen
when the transfer completes because the interrupt handler will corrupt
the stack. If a new transfer is started before the interrupt fires
the controller will start a new transfer in the middle of the old one,
resulting in confused slaves and a locked bus.
To avoid this, use wait_for_completion_io_timeout instead so that we
don't have to deal with gracefully shutting down the transfer and
disabling the interrupts.
Signed-off-by: Simon Lindgren <simon@xxxxxxxxxx>
Acked-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-at91.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -434,8 +434,8 @@ static int at91_do_twi_transfer(struct a
}
}
- ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
- dev->adapter.timeout);
+ ret = wait_for_completion_io_timeout(&dev->cmd_complete,
+ dev->adapter.timeout);
if (ret == 0) {
dev_err(dev->dev, "controller timed out\n");
at91_init_twi_bus(dev);
--
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