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tty: mxser: drop low-latency workaround 

Commit 67d2bc58af ("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 a9c3f68f3c ("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: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2021-04-21 11:54:44 +02:00 committed by Greg Kroah-Hartman
parent e2a5e8448e
commit 02ca144fa4
1 changed files with 0 additions and 7 deletions
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7
drivers/tty/mxser.c
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@ -2155,14 +2155,7 @@ end_intr:
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)