linux-kernel - [PATCH RESEND tty-next] serial: 8250_dw: Take port lock while accessing LSR

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Message-ID: <c5879db7-bee9-93f-526e-872a292442@linux.intel.com>
Date:   Tue, 28 Jun 2022 12:01:28 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Greg KH <gregkh@...uxfoundation.org>
cc:     linux-serial <linux-serial@...r.kernel.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH RESEND tty-next] serial: 8250_dw: Take port lock while
 accessing LSR

Accessing LSR requires port lock because it mutates lsr_saved_flags
in serial_lsr_in().

Fixes: 197eb5c416ff ("serial: 8250_dw: Use serial_lsr_in() in dw8250_handle_irq()")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>

---
I'll resend the third patch later.

 drivers/tty/serial/8250/8250_dw.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 167a691c7b19..f78b13db1b1e 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -266,7 +266,10 @@ static int dw8250_handle_irq(struct uart_port *p)
 
 	/* Manually stop the Rx DMA transfer when acting as flow controller */
 	if (quirks & DW_UART_QUIRK_IS_DMA_FC && up->dma && up->dma->rx_running && rx_timeout) {
+		spin_lock_irqsave(&p->lock, flags);
 		status = serial_lsr_in(up);
+		spin_unlock_irqrestore(&p->lock, flags);
+
 		if (status & (UART_LSR_DR | UART_LSR_BI)) {
 			dw8250_writel_ext(p, RZN1_UART_RDMACR, 0);
 			dw8250_writel_ext(p, DW_UART_DMASA, 1);

-- 
tg: (f55d2e4b0a47..) dw/use-spinlock (depends on: 8250/fix-stop_tx-race)