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    SubjectRe: [PATCH 01/26] tty: mxser: drop low-latency workaround
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    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

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