[BUG] Re: mtd_stresstest module bricked my dockstar

[Wolfram Sang]

On Mon, Oct 24, 2011 at 09:32:42PM +0200, Roland Kletzing wrote:

CCing the mtd-list...

> Hello,
> 
> cc`ing correct email of Adrian Hunter and i found that
> mtd_torturetest (and the
> other modules) have the same issue and there is another author i
> could find the
> email for.
> 
> >If you can't restore it with JTAG, it means the hardware is really dead.
> >JTAG is used when you blank the flash, and is supposed to work. I don't
> >know what the module does, but I fail to see how to could wear the flash
> >that fast. At worst it could have wiped it, or the flash was already bad.
> 
> Yes, i think accidentally insmodding  "mtd_stresstest" has just
> wiped it, not killed.
> The problem is, that it is important stuff for booting and you can`t
> pull it out and
> re-write externally, like a disk. Sorry, i that was probably not
> clearly stated.
> 
> Anyway - what would people think if linux had a kernel module  which wipes
> /dev/sda1 when loaded ? :)
> 
> >I got one Iomega Iconnect with a faulty flash that I got replaced for a
> >good one, so it's more likely the case here.
> 
> Yes, i could give debricking with JTAG a try. But what about the
> cost for the JTAG
> and the work to be spent with it? I could buy another Dockstar for that.....
> 
> >I agree with you. I remember the very old ISA NE2000 driver who used to
> >scan various addresses to find a NIC, causing some of them to reconfigure
> >their address to *none* and definitely stop responding on the bus to any
> >reconfiguration request. That was pretty annoying too. After killing a
> >few, I stopped using Linux on a machine with such a NIC for a long time!
> 
> Oh, that could be an explanation why i had 2 broken NE2000 NICs in
> the nineties.. ;)
> 
> >You should keep it and retry the JTAG adapter. You just need a boot loader
> >so if you manage to find a usable memory location that you can select by
> >soldering two pins together, you could manage to store it and bood from
> >another device.
> 
> I`m sure debricking with JTAG is possible and it would be an
> interesting task.
> Maybe i like to spend some money and time with this one day. For now
> i don`t.
> 
> In the meantime i`d rather being interested in what can be done to add more
> safety to the mtd tests.
> 
> By writing these lines and looking into the source, i started
> getting curious -  i
> see there is dev param with that module(s), but i did not pass a
> device number,
> nor did i pass anything to it.
> 
> in
> 
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=drivers/mtd/tests/mtd_stresstest.c;h=63920476b57a24c7e61563303eb3abb773b73fdf;hb=7163cea15f7b362795b858e7c130cd617aecc0aa
> 
> i see:
> 
> static int dev;   <-!
> module_param(dev, int, S_IRUGO);
> MODULE_PARM_DESC(dev, "MTD device number to use");
> 
> static int count = 10000;
> module_param(count, int, S_IRUGO);
> MODULE_PARM_DESC(count, "Number of operations to do (default is 10000)");
> 
> and then
> 
> static int __init mtd_stresstest_init(void)
> {
> 	int err;
> 	int i, op;
> 	uint64_t tmp;
> 
> 	printk(KERN_INFO "\n");
> 	printk(KERN_INFO "=================================================\n");
> 	printk(PRINT_PREF "MTD device: %d\n", dev);
> 
> 	mtd = get_mtd_device(NULL, dev);
> 	if (IS_ERR(mtd)) {
> 		err = PTR_ERR(mtd);
> 		printk(PRINT_PREF "error: cannot get MTD device\n");
> 		return err;
> 	}
> 
> 
> 
> My kernel log showed:
> 
> mtd_stresstest: MTD device: 0
> mtd_stresstest: MTD device size 1048576 etc...
> 
> So, apparenly the module accidentally picked mtd0 instead of exiting
> cleanly (as
> i did not pass a device number)
> 
> I`m not a programmer, but doesn`t look that like an "unitialized
> variable" issue ?
> 
> If yes, then i would call my Dockstar "victim of a bug".

No, that's okay. Check http://en.wikipedia.org/wiki/.bss

I wonder though, if it makes sense to initialize it with -EINVAL or something,
so a user is forced to use the dev-module parameter?

Regards,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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