Hello Greg, On 12/10/2016 09:32 AM, Greg Kroah-Hartman wrote: > On Sat, Dec 10, 2016 at 02:15:19AM +0200, Vladimir Zapolskiy wrote: >> If CONFIG_DEBUG_TEST_DRIVER_REMOVE option is enabled a number of false >> positives are reported for ATA controller drivers, because ATA port >> probes are done asynchronously, and the same problem may also touch >> other asynchronously probed drivers. >> >> To reduce the rate of false reports on boot call async_synchronize_full() >> before attempting to remove a driver, the same is done in delete_module() >> syscall for all possible drivers and in __device_release_driver() function >> for asynchronously probed drivers. > > __device_release_driver() already calls this function, why call it > again? >
__device_release_driver() is not called on test removal of drivers, if CONFIG_DEBUG_TEST_DRIVER_REMOVE option is enabled. This opens a possibility to races like one I've discovered: https://www.spinics.net/lists/linux-ide/msg53473.html Next, async_synchronize_full() from __device_release_driver() is not called in case of removal of ATA controller drivers, because driver_allows_async_probing(drv) return value is false. -- With best wishes, Vladimir
