RE: The failure summary report of GEN2 for linux stable v4.8

[Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>]

Hi Geert-san, Xuan-san,

> From: linux-renesas-soc-owner@vger.kernel.org [mailto:linux-renesas-soc-owner@vger.kernel.org] On Behalf Of Geert
> Uytterhoeven
> Sent: Monday, October 24, 2016 6:21 PM
> 
> On Mon, Oct 24, 2016 at 11:13 AM, Xuan Truong Nguyen
> <nx-truong@jinso.co.jp> wrote:
> >> This is with shmobile_defconfig?
> >
> > yes. we also attach the configs file we used
> > (lager-scif-pio-v4.9-rc2.config)
> >
> >> Does it work better if you enable CONFIG_SERIAL_SH_SCI_DMA?
> >
> > yes, it's better a little bit. the kernel does not hangs up, but the warning
> > message is output.
> > please refer lager-scif-dma.log.
> >
> > we tested on v4.9-rc2. the issue is the same.
> >
> > if you need any information, please let us know.
> 
> > WARNING: CPU: 0 PID: 2249 at drivers/dma/sh/rcar-dmac.c:1257 rcar_dmac_tx_status+0x128/0x4
> > No descriptor for cookie!
> 
> > [<c03419e8>] (rcar_dmac_tx_status) from [<c0371e04>] (rx_timer_fn+0x48/0x148)
> 
> > [<c0371dbc>] (rx_timer_fn) from [<c016dedc>] (call_timer_fn+0x2c/0xa0)
> 
> That looks like a race condition between timeout handling and actual completion
> of the DMA?

I found an issue in sh-sci.c and made a patch to resolve it.
But, I'm not sure this is correct way.
If this is correct way, we also have to fix dev_dbg() in some functions.

Best regards,
Yoshihiro Shimoda

Since I send this email using Outlook, the patch format may be not good.
---
From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Date: Fri, 28 Oct 2016 16:52:36 +0900
Subject: [PATCH] serial: sh-sci: remove dev_warn() to avoid double spin lock
 held

If we use serial console and CONFIG_SERIAL_SH_SCI_DMA=y, since
sci_dma_rx_push() is called with port->lock held and dev_warn() will
call serial_console_write() finally, this is possible to call
spin_lock{_irqsave}() twice.
To avoid this, this patch remove dev_warn() in sci_dma_rx_push().

Reported-by: Xuan Truong Nguyen <nx-truong@jinso.co.jp>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
 drivers/tty/serial/sh-sci.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 4b26252..380b5d7 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/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;
 
-- 
1.9.1