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[3.13,099/103] i2c: at91: Fix a race condition during signal handling in at91_do_twi_xfer.

Message ID 1412112708-27356-100-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Sept. 30, 2014, 9:31 p.m. UTC 
3.13.11.8 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Simon Lindgren <simon@aqwary.com>

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@aqwary.com>
Acked-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 drivers/i2c/busses/i2c-at91.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index d13d3bb..ae4cdc0 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);