6.1-stable review patch. If anyone has any objections, please let me know.
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From: Simon Arlott simon@octiron.net
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-c6... Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/can/spi/mcp251x.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/can/spi/mcp251x.c +++ b/drivers/net/can/spi/mcp251x.c @@ -753,7 +753,7 @@ static int mcp251x_hw_wake(struct spi_de 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 */