From 6721f28a26efd6368497abbdef5dcfc59608d899 Mon Sep 17 00:00:00 2001 From: Simon Lindgren Date: Tue, 26 Aug 2014 21:13:24 +0200 Subject: [PATCH] i2c: at91: Fix a race condition during signal handling in at91_do_twi_xfer. 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 Acked-by: Ludovic Desroches Signed-off-by: Wolfram Sang Cc: stable@kernel.org --- drivers/i2c/busses/i2c-at91.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c index 79a68999a696..ec299ae17a5a 100644 --- a/drivers/i2c/busses/i2c-at91.c +++ b/drivers/i2c/busses/i2c-at91.c @@ -421,8 +421,8 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) } } - 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); -- 2.20.1