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@xxxxxxxxxxxxxxxxxx>
---
** REQUIRES serial: 8250: Split base port operations from universal driver **
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 888c01a..02c911b 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2008,12 +2008,11 @@ 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;
--
2.4.5
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