linux-kernel - [PATCH] tty: serial: fsl_lpuart: check dma_tx_in

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Message-Id: <20210817100203.21300-1-sherry.sun@nxp.com>
Date:   Tue, 17 Aug 2021 18:02:03 +0800
From:   Sherry Sun <sherry.sun@....com>
To:     gregkh@...uxfoundation.org, jirislaby@...nel.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-imx@....com
Subject: [PATCH] tty: serial: fsl_lpuart: check dma_tx_in_progress in tx dma callback

From: Fugang Duan <fugang.duan@....com>

There have a corner case that tx DMA .callback() is coming after
.flush_buffer(), then .callback() should check dma_tx_in_progress
flag and return in directly.

Signed-off-by: Fugang Duan <fugang.duan@....com>
Signed-off-by: Vipul Kumar <vipul_kumar@...tor.com>
Signed-off-by: Sherry Sun <sherry.sun@....com>
---
 drivers/tty/serial/fsl_lpuart.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 460e428b7592..117e011aff5f 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -479,6 +479,10 @@ static void lpuart_dma_tx_complete(void *arg)
 	unsigned long flags;
 
 	spin_lock_irqsave(&sport->port.lock, flags);
+	if (!sport->dma_tx_in_progress) {
+		spin_unlock_irqrestore(&sport->port.lock, flags);
+		return;
+	}
 
 	dma_unmap_sg(chan->device->dev, sgl, sport->dma_tx_nents,
 		     DMA_TO_DEVICE);
-- 
2.17.1