[PATCH/RFC] serial: sh-sci: Fix exclusion of work_fn_rx and sci_dma_rx_complete

[Yoshihiro Kaneko <ykaneko0929@gmail.com>]

From: Kazuya Mizuguchi <kazuya.mizuguchi.ks@renesas.com>

There is a problem when the sci_dma_rx_complete() is processed
before cancel process of work_fn_rx() completes by rx_timer_fn().
This patch locks work_fn_rx().

Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@renesas.com>
Signed-off-by: Yoshihiro Kaneko <ykaneko0929@gmail.com>
---

This patch is based on the tty-next branch of Greg Kroah-Hartman's tty
tree.

 drivers/tty/serial/sh-sci.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index b74a644..ef59842 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1423,14 +1423,16 @@ static void work_fn_rx(struct work_struct *work)
 	struct uart_port *port = &s->port;
 	struct dma_async_tx_descriptor *desc;
 	int new;
+	unsigned long flags;
 
+	spin_lock_irqsave(&port->lock, flags);
 	if (s->active_rx = s->cookie_rx[0]) {
 		new = 0;
 	} else if (s->active_rx = s->cookie_rx[1]) {
 		new = 1;
 	} else {
 		dev_err(port->dev, "cookie %d not found!\n", s->active_rx);
-		return;
+		goto out;
 	}
 	desc = s->desc_rx[new];
 
@@ -1440,36 +1442,35 @@ static void work_fn_rx(struct work_struct *work)
 		struct dma_chan *chan = s->chan_rx;
 		struct shdma_desc *sh_desc = container_of(desc,
 					struct shdma_desc, async_tx);
-		unsigned long flags;
 		int count;
 
 		dmaengine_terminate_all(chan);
 		dev_dbg(port->dev, "Read %zu bytes with cookie %d\n",
 			sh_desc->partial, sh_desc->cookie);
 
-		spin_lock_irqsave(&port->lock, flags);
 		count = sci_dma_rx_push(s, sh_desc->partial);
-		spin_unlock_irqrestore(&port->lock, flags);
 
 		if (count)
 			tty_flip_buffer_push(&port->state->port);
 
 		sci_submit_rx(s);
 
-		return;
+		goto out;
 	}
 
 	s->cookie_rx[new] = desc->tx_submit(desc);
 	if (s->cookie_rx[new] < 0) {
 		dev_warn(port->dev, "Failed submitting Rx DMA descriptor\n");
 		sci_rx_dma_release(s, true);
-		return;
+		goto out;
 	}
 
 	s->active_rx = s->cookie_rx[!new];
 
 	dev_dbg(port->dev, "%s: cookie %d #%d, new active #%d\n",
 		__func__, s->cookie_rx[new], new, s->active_rx);
+out:
+	spin_unlock_irqrestore(&port->lock, flags);
 }
 
 static void work_fn_tx(struct work_struct *work)
-- 
1.9.1