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Commit ee3ad90b authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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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: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 45c6df44

drivers/tty/serial/8250/8250_port.c

+3 −4
Original line number Diff line number Diff line
@@ -2002,12 +2002,11 @@ int serial8250_do_startup(struct uart_port *port) 
	}



	/*

	 * 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;