Patch "serial: sh-sci: Fix panic when serial console and DMA are enabled" has been added to the 4.4-stable tree

Patch "serial: sh-sci: Fix panic when serial console and DMA are enabled" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    serial: sh-sci: Fix panic when serial console and DMA are enabled

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     serial-sh-sci-fix-panic-when-serial-console-and-dma-are-enabled.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 3c9101766b502a0163d1d437fada5801cf616be2 Mon Sep 17 00:00:00 2001
From: Takatoshi Akiyama <takatoshi.akiyama.kj@ps.hitachi-solutions.com>
Date: Mon, 27 Feb 2017 15:56:31 +0900
Subject: serial: sh-sci: Fix panic when serial console and DMA are enabled

From: Takatoshi Akiyama <takatoshi.akiyama.kj@ps.hitachi-solutions.com>

commit 3c9101766b502a0163d1d437fada5801cf616be2 upstream.

This patch fixes an issue that kernel panic happens when DMA is enabled
and we press enter key while the kernel booting on the serial console.

* An interrupt may occur after sci_request_irq().
* DMA transfer area is initialized by setup_timer() in sci_request_dma()
  and used in interrupt.

If an interrupt occurred between sci_request_irq() and setup_timer() in
sci_request_dma(), DMA transfer area has not been initialized yet.
So, this patch changes the order of sci_request_irq() and
sci_request_dma().

Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.")
Signed-off-by: Takatoshi Akiyama <takatoshi.akiyama.kj@ps.hitachi-solutions.com>
[Shimoda changes the commit log]
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/tty/serial/sh-sci.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1800,11 +1800,13 @@ static int sci_startup(struct uart_port
 
 	dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
 
+	sci_request_dma(port);
+
 	ret = sci_request_irq(s);
-	if (unlikely(ret < 0))
+	if (unlikely(ret < 0)) {
+		sci_free_dma(port);
 		return ret;
-
-	sci_request_dma(port);
+	}
 
 	spin_lock_irqsave(&port->lock, flags);
 	sci_start_tx(port);
@@ -1834,8 +1836,8 @@ static void sci_shutdown(struct uart_por
 	}
 #endif
 
-	sci_free_dma(port);
 	sci_free_irq(s);
+	sci_free_dma(port);
 }
 
 static unsigned int sci_scbrr_calc(struct sci_port *s, unsigned int bps,


Patches currently in stable-queue which might be from takatoshi.akiyama.kj@ps.hitachi-solutions.com are

queue-4.4/serial-sh-sci-fix-panic-when-serial-console-and-dma-are-enabled.patch