uart: fix sleeping while holding mutex in uart_tty_detach()

Move swi_remove() call before acquiring the tty lock. swi_remove() calls
intr_event_remove_handler() which may sleep via msleep(), causing a lock
order violation when called with the tty mutex held.

The software interrupt handler removal operates on the interrupt event
structure independently and does not require the tty lock. This matches
the pattern used in other drivers such as tcp_hpts.c where swi_remove()
is called without holding other locks.

Reviewed by:	imp, kevans
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D54953

This commit is contained in:

Abdelkader Boudih

2026-02-02 21:21:43 -06:00

committed by

Kyle Evans

parent d3f21856aa

commit ed3a2469a7

1 changed files with 2 additions and 1 deletions

									
										sys/dev/uart/uart_tty.c
									
		+2
		-1
	
												View File
												
				@@ -447,8 +447,9 @@ uart_tty_detach(struct uart_softc *sc)

					tp = sc->sc_u.u_tty.tp;

					tty_lock(tp);

					swi_remove(sc->sc_softih);

					tty_lock(tp);

					tty_rel_gone(tp);

					return (0);