patch "Revert "serial: 8250: Don't service RX FIFO if interrupts are" added to tty-next

This is a note to let you know that I've just added the patch titled

Revert "serial: 8250: Don't service RX FIFO if interrupts are

to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-next branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release during the merge window.

If you have any questions about this process, please let me know.

From 3f2640ed7be838c3f05c0d2b0f7c7508e7431e48 Mon Sep 17 00:00:00 2001
From: Oliver Barta <[email protected]>
Date: Wed, 19 Jun 2019 10:16:39 +0200
Subject: Revert "serial: 8250: Don't service RX FIFO if interrupts are
disabled"

This reverts commit 2e9fe539108320820016f78ca7704a7342788380.

Reading LSR unconditionally but processing the error flags only if UART_IIR_RDI bit was set before in IIR may lead to a loss of transmission error information on UARTs where the transmission error flags are cleared by a read of LSR. Information are lost in case an error is detected right before the read of LSR while processing e.g. an UART_IIR_THRI interrupt.

---
 drivers/tty/serial/8250/8250_port.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

index a6fabc7e3b13..c1cec808571b 100644
@@ -1867,8 +1867,7 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
 
 	status = serial_port_in(port, UART_LSR);
 
-	if (status & (UART_LSR_DR | UART_LSR_BI) &&
-	    iir & UART_IIR_RDI) {
+	if (status & (UART_LSR_DR | UART_LSR_BI)) {
 		if (!up->dma || handle_rx_dma(up, iir))
 			status = serial8250_rx_chars(up, status);
 	}

2.22.0