| Message ID | 20210421095509.3024-2-johan@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | tty: drop low-latency workarounds | expand |
On 21. 04. 21, 11:54, Johan Hovold wrote: > Commit 67d2bc58afdd ("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 a9c3f68f3cd8 ("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 > Signed-off-by: Johan Hovold <johan@kernel.org> Reviewed-by: Jiri Slaby <jirislaby@kernel.org> > --- > drivers/tty/mxser.c | 7 ------- > 1 file changed, 7 deletions(-) > > diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c > index 2d8e76263a25..16a852ecbe8a 100644 > --- a/drivers/tty/mxser.c > +++ b/drivers/tty/mxser.c > @@ -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) > thanks, -- js
diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c index 2d8e76263a25..16a852ecbe8a 100644 --- a/drivers/tty/mxser.c +++ b/drivers/tty/mxser.c @@ -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)
Commit 67d2bc58afdd ("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 a9c3f68f3cd8 ("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 Signed-off-by: Johan Hovold <johan@kernel.org> --- drivers/tty/mxser.c | 7 ------- 1 file changed, 7 deletions(-)