On Wed, Jun 23, 2021 at 11:06:53AM +0530, Saubhik Mukherjee wrote: > On 6/17/21 4:52 PM, Greg KH wrote: > > On Thu, Jun 17, 2021 at 04:34:43PM +0530, Saubhik Mukherjee wrote: > >> Suppose the driver is registered and a UART port is added. Once an > >> application opens the port, owl_uart_startup is called which registers > >> the interrupt handler owl_uart_irq. > >> > >> We could have the following race condition: > >> > >> When device is removed, owl_uart_remove is called, which calls > >> uart_remove_one_port, which calls owl_uart_release_port, which writes > >> NULL to port->membase. At this point parallely, an interrupt could be > >> handled by owl_uart_irq which reads port->membase. > >> > >> This is because it is possible to remove device without closing a port. > >> Thus, we need to check it and call owl_uart_shutdown in owl_uart_remove. No, this makes no sense at all. The port is deregistered and hung up by uart_remove_one_port() (and the interrupt line is consequently disabled by the driver) before it is released so this can never happen. > >> Found by Linux Driver Verification project (linuxtesting.org). And you clearly did not test this, which you should mention. Johan
