On Fri, Jun 11, 2021 at 03:03:42PM +0530, Saubhik Mukherjee wrote: > Consider the following events involving drivers/tty/serial/owl-uart.c: > > Suppose the driver is registered, and the owl_uart_probe() was called. > Then uart_startup() can be called in serial core. This calls > owl_uart_startup() which registers the interrupt handler owl_uart_irq. > > Now suppose uart_remove_one_port() in serial core is called. This > detaches port from the core. This calls owl_uart_release_port(port). > This writes NULL to port->membase after iounmap of port->membase from > port->dev. > > During this point, an interrupt is triggered and the interrupt callback > owl_uart_irq() is called (parallel with uart_remove_one_port()). This > tries to read port->membase to send or receive chars (with spinlock on > port->lock). This introduces a race condition on port->membase. > > QUESTION: Is it possible to remove an active port (without shutdown)? You can remove it, if the driver is set up to do so properly. Odds are the owl-uart code is not written to expect that to ever happen. How are you "removing" an active port? What triggers this action? thanks, greg k-h
