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

Sandy Harris (sandy@storm.ca)
Sat, 20 Jan 2001 16:58:56 -0500


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;
> }
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