linux-kernel - [PATCH V3] tty: serial: fsl_lpuart: count tty buffer overruns

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Date:   Tue, 11 Jan 2022 16:51:30 +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 V3] tty: serial: fsl_lpuart: count tty buffer overruns

Added support for counting the tty buffer overruns in fsl_lpuart driver
like other uart drivers.

Signed-off-by: Sherry Sun <sherry.sun@....com>
---
changes in V3

1. Remove the initialization for copied as it is not necessary.
---
 drivers/tty/serial/fsl_lpuart.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index ce3e26144689..7d90c5a530ee 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -931,7 +931,8 @@ static void lpuart_rxint(struct lpuart_port *sport)
 			sport->port.sysrq = 0;
 		}
 
-		tty_insert_flip_char(port, rx, flg);
+		if (tty_insert_flip_char(port, rx, flg) == 0)
+			sport->port.icount.buf_overrun++;
 	}
 
 out:
@@ -1024,7 +1025,8 @@ static void lpuart32_rxint(struct lpuart_port *sport)
 				flg = TTY_OVERRUN;
 		}
 
-		tty_insert_flip_char(port, rx, flg);
+		if (tty_insert_flip_char(port, rx, flg) == 0)
+			sport->port.icount.buf_overrun++;
 	}
 
 out:
@@ -1116,7 +1118,7 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport)
 	struct dma_chan *chan = sport->dma_rx_chan;
 	struct circ_buf *ring = &sport->rx_ring;
 	unsigned long flags;
-	int count = 0;
+	int count = 0, copied;
 
 	if (lpuart_is_32(sport)) {
 		unsigned long sr = lpuart32_read(&sport->port, UARTSTAT);
@@ -1218,20 +1220,24 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport)
 	if (ring->head < ring->tail) {
 		count = sport->rx_sgl.length - ring->tail;
 
-		tty_insert_flip_string(port, ring->buf + ring->tail, count);
+		copied = tty_insert_flip_string(port, ring->buf + ring->tail, count);
+		if (copied != count)
+			sport->port.icount.buf_overrun++;
 		ring->tail = 0;
-		sport->port.icount.rx += count;
+		sport->port.icount.rx += copied;
 	}
 
 	/* Finally we read data from tail to head */
 	if (ring->tail < ring->head) {
 		count = ring->head - ring->tail;
-		tty_insert_flip_string(port, ring->buf + ring->tail, count);
+		copied = tty_insert_flip_string(port, ring->buf + ring->tail, count);
+		if (copied != count)
+			sport->port.icount.buf_overrun++;
 		/* Wrap ring->head if needed */
 		if (ring->head >= sport->rx_sgl.length)
 			ring->head = 0;
 		ring->tail = ring->head;
-		sport->port.icount.rx += count;
+		sport->port.icount.rx += copied;
 	}
 
 exit:
-- 
2.17.1