Commit 02ca144f authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
Browse files

tty: mxser: drop low-latency workaround 

Commit 67d2bc58 ("Char: mxser_new, fix recursive locking") worked
around the infamous low_latency behaviour of tty_flip_buffer_push() by
simply dropping and reacquiring the port lock in the interrupt handler.

Since commit a9c3f68f ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.

Link: https://lore.kernel.org/lkml/3018694794025219@wsc.cz/T/#m06b04c640a7b6f41afb3d34a4cf29b1df4935d3a


Reviewed-by: default avatarJiri Slaby <jirislaby@kernel.org>
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-2-johan@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e2a5e844

drivers/tty/mxser.c

+0 −7
Original line number Diff line number Diff line
@@ -2155,14 +2155,7 @@ static void mxser_receive_chars(struct tty_struct *tty, 
	port->mon_data.rxcnt += cnt;

	port->mon_data.up_rxcnt += cnt;



	/*

	 * We are called from an interrupt context with &port->slock

	 * being held. Drop it temporarily in order to prevent

	 * recursive locking.

	 */

	spin_unlock(&port->slock);

	tty_flip_buffer_push(&port->port);

	spin_lock(&port->slock);

}



static void mxser_transmit_chars(struct tty_struct *tty, struct mxser_port *port)