On 08/02/2016 03:12 AM, Brian Norris wrote: > Hi all, > > I'm seeing the following warnings when I read from an IIO char device, > with CONFIG_DEBUG_ATOMIC_SLEEP=y. I'm testing a v4.4 kernel, but AFAICT, > nothing too relevant has changed between that and v4.7: [...] > Have any of you seen this kind of issue before (perhaps most IIO users > are not using CONFIG_DEBUG_ATOMIC_SLEEP)? If the WARNING is really > correct, then this problem has really been around a while. It looks like > we have a wait_event_interruptible() called, with this call chain in the > 'condition' path: > > iio_buffer_ready() > -> iio_buffer_data_available() (i.e., iio_kfifo_buf_data_available()) > -> mutex_lock() > > Calling mutex_lock() means we clobber the TASK_INTERRUPTIBLE state with > TASK_RUNNING -- hence, the WARNING. Should this be using a spinlock > instead? Or is there some way to refactor this to avoid calling these > sleeping functions in the wait_event*() condition? Hi, Yes, this is an issue, thanks for pointing this out. It has been there for a while, my fault, sorry for that. We need a solution like pointed out in this article (https://lwn.net/Articles/628628/). - Lars -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
