On Sun, Jan 10, 2016 at 01:42:44PM -0800, Peter Hurley wrote: > The tty/serial core uses 5 bits in the tty_port.flags field to > manage state. They are: > > ASYNCB_INITIALIZED > ASYNCB_SUSPENDED > ASYNCB_NORMAL_ACTIVE > - and - > ASYNCB_CTS_FLOW > ASYNCB_CHECK_CD > > Unfortunately, updates to this field (tty_port.flags) are often > non-atomic. Additionally, the field is visible to/modifiable by > userspace (the first 3 bits above are not modifiable by userspace > though). Lastly, the multi-bit ASYNC_SPD_ bitfield is in this > tty_port.flags field as well. > > What needs to happen is the tty/serial core needs to update its > state transitions atomically. I want to re-define the above 5 flags > into a separate field in the tty_port structure and designate new > symbols for these bits. The base patch that does this is inlined > below. > > This will break out-of-tree drivers but I don't really see a > realistic alternative. Also, I think the new symbol prefix ASY_ isn't > great and I'd like to get some suggestions. Don't worry about breaking out-of-tree drivers, that's fine. And try "hiding" the symbol prefix behind inline functions (tty_port_initialized(port) and the like) that way the prefix of the symbol, or even how you do this with locking or bits or atomics will all not matter at all. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
