can: mcp251x: fix deadlock if an interrupt occurs during mcp251x_open

commit 7dd9c26bd6cf679bcfdef01a8659791aa6487a29 upstream.

The mcp251x_hw_wake() function is called with the mpc_lock mutex held and
disables the interrupt handler so that no interrupts can be processed while
waking the device. If an interrupt has already occurred then waiting for
the interrupt handler to complete will deadlock because it will be trying
to acquire the same mutex.

CPU0                           CPU1
----                           ----
mcp251x_open()
 mutex_lock(&priv->mcp_lock)
  request_threaded_irq()
                               <interrupt>
                               mcp251x_can_ist()
                                mutex_lock(&priv->mcp_lock)
  mcp251x_hw_wake()
   disable_irq() <-- deadlock

Use disable_irq_nosync() instead because the interrupt handler does
everything while holding the mutex so it doesn't matter if it's still
running.

Fixes: 8ce8c0abcba3 ("can: mcp251x: only reset hardware as required")
Signed-off-by: Simon Arlott <simon@octiron.net>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/4fc08687-1d80-43fe-9f0d-8ef8475e75f6@0882a8b5-c6c3-11e9-b005-00805fc181fe.uuid.home.arpa
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/can/spi/mcp251x.c b/drivers/net/can/spi/mcp251x.c
index ffcb04aac9729ece57edce656e526f5613a34f45..88d065718e9905f20f4c97a58f5618ba46c01f29 100644 (file)
--- a/drivers/net/can/spi/mcp251x.c
+++ b/drivers/net/can/spi/mcp251x.c
@@ -755,7 +755,7 @@ static int mcp251x_hw_wake(struct spi_device *spi)
        int ret;
 
        /* Force wakeup interrupt to wake device, but don't execute IST */
-       disable_irq(spi->irq);
+       disable_irq_nosync(spi->irq);
        mcp251x_write_2regs(spi, CANINTE, CANINTE_WAKIE, CANINTF_WAKIF);
 
        /* Wait for oscillator startup timer after wake up */