[4.9,107/119] serial: sh-sci: Fix panic when serial console and DMA are enabled
diff mbox series

Message ID 20170612152604.085850314@linuxfoundation.org
State New, archived
Headers show
  • 4.9.32-stable review
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Commit Message

Greg Kroah-Hartman June 12, 2017, 3:26 p.m. UTC
4.9-stable review patch.  If anyone has any objections, please let me know.


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

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(-)

diff mbox series

--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1976,11 +1976,13 @@  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);
+	}
 	return 0;
@@ -2012,8 +2014,8 @@  static void sci_shutdown(struct uart_por
-	sci_free_dma(port);
+	sci_free_dma(port);
 static int sci_sck_calc(struct sci_port *s, unsigned int bps,