linux-kernel - [PATCH 3/6] serial: 8250: 8250_omap: Move locking out from __dma_rx_do

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Date:   Thu, 19 Mar 2020 16:33:41 +0530
From:   Vignesh Raghavendra <vigneshr@...com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>
CC:     Vignesh Raghavendra <vigneshr@...com>,
        <linux-serial@...r.kernel.org>, <linux-omap@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH 3/6] serial: 8250: 8250_omap: Move locking out from __dma_rx_do_complete()

From: Peter Ujfalusi <peter.ujfalusi@...com>

Caller functions of __dma_rx_do_complete() already hold rx_dma_lock.
Therefore move locking out of the function to avoid need to release and
reacquire lock.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
Signed-off-by: Vignesh Raghavendra <vigneshr@...com>
---
 drivers/tty/serial/8250/8250_omap.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index be2b7d374e60..aef0535b62a4 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -736,22 +736,19 @@ static void omap_8250_unthrottle(struct uart_port *port)
 #ifdef CONFIG_SERIAL_8250_DMA
 static int omap_8250_rx_dma(struct uart_8250_port *p);
 
+/* Must be called while priv->rx_dma_lock is held */
 static void __dma_rx_do_complete(struct uart_8250_port *p)
 {
-	struct omap8250_priv	*priv = p->port.private_data;
 	struct uart_8250_dma    *dma = p->dma;
 	struct tty_port         *tty_port = &p->port.state->port;
 	struct dma_chan		*rxchan = dma->rxchan;
 	dma_cookie_t		cookie;
 	struct dma_tx_state     state;
 	int                     count;
-	unsigned long		flags;
 	int			ret;
 
-	spin_lock_irqsave(&priv->rx_dma_lock, flags);
-
 	if (!dma->rx_running)
-		goto unlock;
+		goto out;
 
 	cookie = dma->rx_cookie;
 	dma->rx_running = 0;
@@ -777,13 +774,12 @@ static void __dma_rx_do_complete(struct uart_8250_port *p)
 		}
 	}
 	if (!count)
-		goto unlock;
+		goto out;
 	ret = tty_insert_flip_string(tty_port, dma->rx_buf, count);
 
 	p->port.icount.rx += ret;
 	p->port.icount.buf_overrun += count - ret;
-unlock:
-	spin_unlock_irqrestore(&priv->rx_dma_lock, flags);
+out:
 
 	tty_flip_buffer_push(tty_port);
 }
@@ -836,9 +832,8 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p)
 		if (WARN_ON_ONCE(ret))
 			priv->rx_dma_broken = true;
 	}
-	spin_unlock_irqrestore(&priv->rx_dma_lock, flags);
-
 	__dma_rx_do_complete(p);
+	spin_unlock_irqrestore(&priv->rx_dma_lock, flags);
 }
 
 static int omap_8250_rx_dma(struct uart_8250_port *p)
-- 
2.25.2