serial: sh-sci: Fix deadlock caused by serial output request

While spin is already locked, serial output request causes the deadlock,
because serial output process also tries to lock the spin.
This patch removes serial output with spin locked.
Signed-off-by: Takatoshi Akiyama <takatoshi.akiyama.kj@ps.hitachi-solutions.com>
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/sh-sci.c

@@ -1142,11 +1142,8 @@ static int sci_dma_rx_push(struct sci_port *s, void *buf, size_t count)
 	int copied;
 
 	copied = tty_insert_flip_string(tport, buf, count);
-	if (copied < count) {
-		dev_warn(port->dev, "Rx overrun: dropping %zu bytes\n",
-			 count - copied);
+	if (copied < count)
 		port->icount.buf_overrun++;
-	}
 
 	port->icount.rx += copied;
 
@@ -1161,8 +1158,6 @@ static int sci_dma_rx_find_active(struct sci_port *s)
 		if (s->active_rx == s->cookie_rx[i])
 			return i;
 
-	dev_err(s->port.dev, "%s: Rx cookie %d not found!\n", __func__,
-		s->active_rx);
 	return -1;
 }
 
@@ -1223,9 +1218,9 @@ static void sci_dma_rx_complete(void *arg)
 
 	dma_async_issue_pending(chan);
 
+	spin_unlock_irqrestore(&port->lock, flags);
 	dev_dbg(port->dev, "%s: cookie %d #%d, new active cookie %d\n",
 		__func__, s->cookie_rx[active], active, s->active_rx);
-	spin_unlock_irqrestore(&port->lock, flags);
 	return;
 
 fail:
@@ -1273,8 +1268,6 @@ static void sci_submit_rx(struct sci_port *s)
 		if (dma_submit_error(s->cookie_rx[i]))
 			goto fail;
 
-		dev_dbg(s->port.dev, "%s(): cookie %d to #%d\n", __func__,
-			s->cookie_rx[i], i);
 	}
 
 	s->active_rx = s->cookie_rx[0];
@@ -1288,7 +1281,6 @@ static void sci_submit_rx(struct sci_port *s)
 	for (i = 0; i < 2; i++)
 		s->cookie_rx[i] = -EINVAL;
 	s->active_rx = -EINVAL;
-	dev_warn(s->port.dev, "Failed to re-start Rx DMA, using PIO\n");
 	sci_rx_dma_release(s, true);
 }
 
@@ -1358,10 +1350,10 @@ static void rx_timer_fn(unsigned long arg)
 	int active, count;
 	u16 scr;
 
-	spin_lock_irqsave(&port->lock, flags);
-
 	dev_dbg(port->dev, "DMA Rx timed out\n");
 
+	spin_lock_irqsave(&port->lock, flags);
+
 	active = sci_dma_rx_find_active(s);
 	if (active < 0) {
 		spin_unlock_irqrestore(&port->lock, flags);
@@ -1370,9 +1362,9 @@ static void rx_timer_fn(unsigned long arg)
 
 	status = dmaengine_tx_status(s->chan_rx, s->active_rx, &state);
 	if (status == DMA_COMPLETE) {
+		spin_unlock_irqrestore(&port->lock, flags);
 		dev_dbg(port->dev, "Cookie %d #%d has already completed\n",
 			s->active_rx, active);
-		spin_unlock_irqrestore(&port->lock, flags);
 
 		/* Let packet complete handler take care of the packet */
 		return;
@@ -1396,8 +1388,6 @@ static void rx_timer_fn(unsigned long arg)
 	/* Handle incomplete DMA receive */
 	dmaengine_terminate_all(s->chan_rx);
 	read = sg_dma_len(&s->sg_rx[active]) - state.residue;
-	dev_dbg(port->dev, "Read %u bytes with cookie %d\n", read,
-		s->active_rx);
 
 	if (read) {
 		count = sci_dma_rx_push(s, s->rx_buf[active], read);