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[Medium] termios/TIOCM ioctls waiting behind a blocking write: this is a trade-off discussed on v8, where Loic chose a single ops_lock for now, with finer-grained locking possibly later. In v10 the lock is only held around the termios/TIOCM state, never across a user copy, the wait is interruptible, and ioctls that don't touch that state don't take it. No in-tree driver implements both ->tx_blocking and ->dtr_rts, so the circular wait you describe can't happen today. If the maintainers would rather keep the termios/TIOCM state under a lock the TX path doesn't hold, I'm happy to do that as a follow-up.