i2c: designware: Synchronize IRQs when unregistering slave client

Make sure interrupt handler i2c_dw_irq_handler_slave() has finished
before clearing the the dev->slave pointer in i2c_dw_unreg_slave().

There is possibility for a race if i2c_dw_irq_handler_slave() is running
on another CPU while clearing the dev->slave pointer.

Reported-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
Reported-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-designware-slave.c b/drivers/i2c/busses/i2c-designware-slave.c
index e7f9305..f5f0017 100644 (file)
--- a/drivers/i2c/busses/i2c-designware-slave.c
+++ b/drivers/i2c/busses/i2c-designware-slave.c
@@ -94,6 +94,7 @@ static int i2c_dw_unreg_slave(struct i2c_client *slave)
 
        dev->disable_int(dev);
        dev->disable(dev);
+       synchronize_irq(dev->irq);
        dev->slave = NULL;
        pm_runtime_put(dev->dev);