From ee3ad90be5ec5e94a45aac597a23b1050cd4f1b0 Mon Sep 17 00:00:00 2001
From: Peter Hurley <peter@hurleysoftware.com>
Date: Sun, 12 Jul 2015 21:11:31 -0400
Subject: 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 <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/8250/8250_port.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
(limited to 'drivers/tty')
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;
--
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