On Wed, Jan 14, 2015 at 11:47:35AM -0800, prasad.koya@xxxxxxxxx wrote: > From: Prasad Koya <prasad@xxxxxxxxxx> > > At slow baud rates, say 9600, it is easy to run into tty buffer overrun > as interrupts could get disabled for a long time. To avoid that, if > UART_LSR_DR is set, pick up bytes from rx fifo while waiting for tx > buffer to be empty. Stop buffering if port->sysrq is true or > oops_in_progress is set. > > George Spelvin reworked original patch quite a bit. > > Tested on 16550 UART with 16byte FIFO > > Signed-off-by: Prasad Koya <prasad@xxxxxxxxxx> > Signed-off-by: George Spelvin <linux@xxxxxxxxxxx> > --- > drivers/tty/serial/8250/8250_core.c | 65 +++++++++++++++++++++++++++++++++---- > drivers/tty/serial/8250/8250_fsl.c | 2 +- > include/linux/serial_8250.h | 3 +- > include/linux/serial_core.h | 2 +- > 4 files changed, 63 insertions(+), 9 deletions(-) > > diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c > index 11c6685..a9adf9d 100644 > --- a/drivers/tty/serial/8250/8250_core.c > +++ b/drivers/tty/serial/8250/8250_core.c > @@ -1434,9 +1434,12 @@ static void serial8250_enable_ms(struct uart_port *port) > * serial8250_rx_chars: processes according to the passed in LSR > * value, and returns the remaining LSR bits not handled > * by this Rx routine. > + * no_sysrq is normally false, but when set it indicates we should stop > + * processing input after receiving a break, rather than passing the > + * next character to uart_handle_sysrq_char. > */ > unsigned char > -serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr) > +serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr, bool no_sysrq) I hate functions that have "bool" variables like this, it's a mess and can cause them to do different things so you always have to look up the details. Why isn't this a problem with other uarts and slow baud rates? Why hasn't this problem ever been reported in the past for other uarts? Is this really the best/only way to solve this? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
