[PATCH] sky2: detect and prevent kernel panic from a possible faulty hardware

[PATCH] sky2: detect and prevent kernel panic from a possible faulty hardware

[Samuel Williams]

A possible faulty hardware might interrupt with a status of 0xffffffff which
may kernel panic if sky2 driver tries to handle it. Detecting this problem
may avoid kernel panic.

Signed-off-by: Samuel Williams <sam8641@gmail.com>
---
 drivers/net/ethernet/marvell/sky2.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/sky2.c b/drivers/net/ethernet/marvell/sky2.c
index e09a8c6..43fe2f3 100644
--- a/drivers/net/ethernet/marvell/sky2.c
+++ b/drivers/net/ethernet/marvell/sky2.c
@@ -3049,8 +3049,17 @@ static int sky2_poll(struct napi_struct *napi, int work_limit)
 	int work_done = 0;
 	u16 idx;
 
-	if (unlikely(status & Y2_IS_ERROR))
+	if (unlikely(status & Y2_IS_ERROR)) {
+		if (status == 0xFFFFFFFF) {
+			dev_err(&hw->pdev->dev,
+				"fatal hardware inturrupt error\n");
+			napi_complete(napi);
+			napi_disable(&hw->napi);
+			return 0;
+		}
 		sky2_err_intr(hw, status);
+	}
+
 
 	if (status & Y2_IS_IRQ_PHY1)
 		sky2_phy_intr(hw, 0);
-- 
1.7.10.4

Re: [PATCH] sky2: detect and prevent kernel panic from a possible faulty hardware

[David Miller]

From: Samuel Williams <sam8641@gmail.com>
Date: Sat, 27 Jul 2013 15:35:54 -0500

> A possible faulty hardware might interrupt with a status of 0xffffffff which
> may kernel panic if sky2 driver tries to handle it. Detecting this problem
> may avoid kernel panic.
> 
> Signed-off-by: Samuel Williams <sam8641@gmail.com>

Sure, but then the device is basically just going to stop.

I think this change needs to be more comprehensive, for example it
needs to fully reset the device and try to get it operational again.

Re: [PATCH] sky2: detect and prevent kernel panic from a possible faulty hardware

[Stephen Hemminger]

On Tue, 30 Jul 2013 16:19:06 -0700 (PDT)
David Miller <davem@davemloft.net> wrote:

> From: Samuel Williams <sam8641@gmail.com>
> Date: Sat, 27 Jul 2013 15:35:54 -0500
> 
> > A possible faulty hardware might interrupt with a status of 0xffffffff which
> > may kernel panic if sky2 driver tries to handle it. Detecting this problem
> > may avoid kernel panic.
> > 
> > Signed-off-by: Samuel Williams <sam8641@gmail.com>
> 
> Sure, but then the device is basically just going to stop.
> 
> I think this change needs to be more comprehensive, for example it
> needs to fully reset the device and try to get it operational again.

Not only that it is going to assert IRQ until the device is hard
reset. Plus it is not clear that cleaning up after sick hardware
is possible at all.

Re: [PATCH] sky2: detect and prevent kernel panic from a possible faulty hardware

[Oliver Neukum]

On Tue, 2013-07-30 at 16:19 -0700, David Miller wrote:
> From: Samuel Williams <sam8641@gmail.com>
> Date: Sat, 27 Jul 2013 15:35:54 -0500
> 
> > A possible faulty hardware might interrupt with a status of 0xffffffff which
> > may kernel panic if sky2 driver tries to handle it. Detecting this problem
> > may avoid kernel panic.
> > 
> > Signed-off-by: Samuel Williams <sam8641@gmail.com>
> 
> Sure, but then the device is basically just going to stop.
> 
> I think this change needs to be more comprehensive, for example it
> needs to fully reset the device and try to get it operational again.

But sky2 is used in some hotremovable cards. You can hit the window
for this race. It is unlikely but still this simple check fixes a bug.

	Regards
		Oliver