Michael Chan wrote:

On Thu, 2010-03-11 at 10:05 -0800, David Miller wrote:

quoted

From: "Michael Chan" <mchan@broadcom.com>
Date: Thu, 11 Mar 2010 09:49:56 -0800

quoted

On Wed, 2010-03-10 at 18:09 -0800, Brian Haley wrote:

quoted

quoted

quoted

I'm able to cause a netdev_watchdog timeout by changing the coalesce
settings on my bnx2, I built a little test program for it:

Do you run this program in a loop?  How quickly do you see the NETDEV
WATCHDOG?

It's run once, and we see it almost immediately after ETHTOOL_SCOALESCE.

What's the difference between running the test program and doing ethtool
-C?  Do you see the issue in either case?  I don't see the issue here
with ethtool -C.

Probably because the independent program runs faster and thus
can trigger races more easily.

A customer provided some test code that triggered this hang, so
I've just been using it.  I just used ethtool and it happened too:

# ethtool -C eth0 rx-usecs 0 rx-frames 1 rx-usecs-irq 0 rx-frames-irq 1

If the interface is down, no problem.

That's what I thought, I thought he was running it in a loop and
triggering some race condition.  But he said he only ran it once.  His
program gets the coalesce settings, sleeps for 5 seconds, and then sets
the coalesce settings.

The 5 seconds was there only because this was a snippet from a larger
function that was doing a lot of ETHTOOL ioctl()'s, and I wanted to
wait between each call to see which was causing this.  Removing the
sleep() still triggers the watchdog.

quoted

In any case, you should be trying to reproduce his problem with
his test program since he went through the effort of providing
one.

I just tried it and cannot reproduce the problem.

Brian, please provide more information.  Thanks.

I can only reproduce this on one system out of many, so it's either a
race condition or bad hardware.  The only thing I can confirm at the
moment is that it's the code at the bottom of bnx2_set_coalesce()
that's causing it, I'm trying to go through all those codepaths now.

# lspci -vv -s 04:00
04:00.0 Ethernet controller: Broadcom Corporation NetXtreme II BCM5708 Gigabit Ethernet (rev 12)
	Subsystem: Hewlett-Packard Company NC373i Integrated Multifunction Gigabit Server Adapter
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop- ParErr+ Stepping- SERR+ FastB2B- DisINTx+
	Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 64 (16000ns min), Cache Line Size: 64 bytes
	Interrupt: pin A routed to IRQ 65
	Region 0: Memory at f6000000 (64-bit, non-prefetchable) [size=32M]
	[virtual] Expansion ROM at d0200000 [disabled] [size=2K]
	Capabilities: [40] PCI-X non-bridge device
		Command: DPERE- ERO- RBC=512 OST=8
		Status: Dev=04:00.0 64bit+ 133MHz+ SCD- USC- DC=simple DMMRBC=512 DMOST=8 DMCRS=32 RSCEM- 266MHz- 533MHz-
	Capabilities: [48] Power Management version 2
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot+,D3cold+)
		Status: D0 PME-Enable- DSel=0 DScale=1 PME-
	Capabilities: [50] Vital Product Data <?>
	Capabilities: [58] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable+
		Address: 00000000fee0100c  Data: 4182
	Kernel driver in use: bnx2
	Kernel modules: bnx2

# ethtool -i eth0
driver: bnx2
version: 2.0.2
firmware-version: 1.9.6
bus-info: 0000:04:00.0

What other info would help?

-Brian