From ee3ad90be5ec5e94a45aac597a23b1050cd4f1b0 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Sun, 12 Jul 2015 21:11:31 -0400 Subject: [PATCH] serial: 8250: Defer interrupt enable until fifos enabled An already-active sender can swamp the interrupt handler with "too much work" if the rx interrupts are enabled when the fifo is disabled and operating in single-byte mode. Defer rx and line status interrupt enable until after the fifos are enabled in set_termios(), but at least initialize the shadow IER value with the interrupts which will be enabled. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_port.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 4dc143eee086..de6655d50c37 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2002,12 +2002,11 @@ dont_test_tx_en: } /* - * Finally, enable interrupts. Note: Modem status interrupts - * are set via set_termios(), which will be occurring imminently - * anyway, so we don't enable them here. + * Set the IER shadow for rx interrupts but defer actual interrupt + * enable until after the FIFOs are enabled; otherwise, an already- + * active sender can swamp the interrupt handler with "too much work". */ up->ier = UART_IER_RLSI | UART_IER_RDI; - serial_port_out(port, UART_IER, up->ier); if (port->flags & UPF_FOURPORT) { unsigned int icp; -- 2.20.1