Re: md= broken. Found problem. Can't fix it. : (

[Sandy Harris]

Dave Cinege wrote:
> 
> ... 'md=' for each device on
> the cmdline, but unfortuantly it's broken.
> 
> Between a few emails to mingo and several wasted hours, I've managed to figure
> out the problem. However I don't know how to fix it; it *should*
> be working from what I can see.
> 
> My only guess right now is because I'm using gcc 2.95.2, and it's doing
> something funky. (And I do not have another version to test with right now.)
> 
> The problem is during parsing of the md= line, name_to_kdev_t() is not
> returning the proper k_dev_t for the device. (IE /dev/sdd5 returns as
> 16:45 /dev/sde5 returns as 20:05.)

Looks to me like this parsing code unnecessarily and rather clumsily re-invents
strtok() and should be rewritten to use that function. It takes two nested loops,
along the general lines of:

	/*
	outer loop, parse into space-separted strings
	*/
	for( p = strtok(str, " ") ; p != NULL ; p = strtok(NULL, " ")	{
		/*
		inner loop using comma separator
		*
		for( q = strtok( p, ",") ; q != NULL ; q = strtok(NULL, ",")	{

		}
	}

I suspect that I've misunderstood some constraint here. Perhaps the more complex
code you posted is necessary, but I'd like to know why.
 
> However if I pass static text to name_to_kdev_t(), it works. I first believed
> it was in how the str pointer was sent to name_to_kdev_t(), (running over into
> comma's, instead of seperate terminated strings) I
> fixed that but the problem persists.
> 
> My current test for loop is attached. The hard coded device names
> printk out to a proper major:minor. The devicenames obtained from
> 'str' don't. I don't see the bug in here or name_to_kdev_t()...
> 
> I'm testing this with the following cmdline:
> root=/dev/md0 raid=noautodetect md=0,/dev/hdd5,/dev/hde5
> md=1,/dev/hdd6,/dev/hde6  md=2,/dev/hdd7,/dev/hde7
> md=3,/dev/hdd8,/dev/hde8 mem=524288K
> 
> --
> "Nobody will ever be safe until the last cop is dead."
>                 NH Rep. Tom Alciere - (My new Hero)
> 
>   --------------------------------------------------------------------------------------------------------------------------------
> 2.4.1prepatch 8
> drivers/md/md.c line 3722
> 
>         for (; i < MD_SB_DISKS && str; i++) {
>                 /*
>                 if ((device = name_to_kdev_t(str))) {
>                         md_setup_args.devices[minor][i] = device;
>                 } else {
>                         printk ("md: Unknown device name, %s.\n", str);
>                         return 0;
>                 }
>                 if ((str = strchr(str, ',')) != NULL)
>                         str++;
>                 */
> 
>                 char *ndevstr;
>                 ndevstr = strchr(str, ',');     // Goto ','
>                 if (ndevstr != NULL)
>                         *ndevstr++ = 0;         // Zero it for proper string
> 
>                 // DEBUG Print device name
>                 printk("Checking: '%s'\n", str);
> 
> 
>                 // Convert device name to k_dev_t and assign to md_setup_args.devices
>                 // DEBUG As test, hardcode device names for /dev/md0.0 and /dev/md0.1
>                 if (minor == 0 && i == 0)
>                         md_setup_args.devices[minor][i] = name_to_kdev_t("/dev/sdd5");
>                 else if (minor == 0 && i == 1)
>                         md_setup_args.devices[minor][i] = name_to_kdev_t("/dev/sde5");
>                 else
>                         md_setup_args.devices[minor][i] = name_to_kdev_t(str);
> 
>                 // DEBUG Print out kdevname of md_setup_args.devices
>                 printk("\t%s\n", kdevname(md_setup_args.devices[minor][i]));
>                 // DEBUG Print minor and i (insync?)
>                 printk("minor=%d, i=%d\n",minor, i);
> 
>                 // name_to_kdev_t() returned 0. Invalid device
>                 if (md_setup_args.devices[minor][i] == 0) {
>                         printk ("md: Unknown device name, %s.\n", str);
>                         return 0;
>                 }
>                 // Jump to next devname in str
>                 str = ndevstr;
>         }