panic: dev ... is on clonelist
From: Andrew Gallatin (gallatin_at_cs.duke.edu)
Date: 03/04/05
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Date: Thu, 3 Mar 2005 18:01:17 -0500 (EST) To: freebsd-current@freebsd.org
Hi,
I've got a character driver which I'd like to make behave as much like
a linux cloning driver as possible because I'm maintaining linux
binary compat. I'm using the cloning interface in 5.x and 6.0.
My driver *seems* to work fine in 5.4, even with INVARIANTS. But in
6.0, I'm dying with: "dev 0xc2f89c00 (mx_fake.1) is on clonelist".
>From the si_drv{1,2} fields, it looks like the cdev was closed.
Did something change between 5.x and 6.0? Or am I doing something
that's bogus in 5.x and I'm just getting lucky?
What I want is to have a unique cdev generated for each open
of the device. Then I would like to use the si_drv1 and
si_drv2 fields of the cdev to hang per-open information from.
So, if the user opens /dev/mx0, then I'd like a unique cdev generated.
And if somebody else opens /dev/mx0, then I'd like a second unique cdev
generated.
What I've been doing (and what seemed to work in 5.x) was this:
- Don't make any /dev/mx devices at all, use clone handler for all
device creation.
- Use dev_stdclone() in to get the "real" unit number (0 from /dev/mx0,
1 from /dev/mx1, etc, where the unit corresponds to a physical
device).
- Prepare a "fake" device for the user, so that every open
has a unique cdev. To do this, I have been calling
clone_create() with a "fake" unit number (starting at 0,
and increasing) until I find either a free "fake" cdev, or
a "fake" cdev which does not exist. By free, I make
a cdev whose si_drv1 indicates he's free. By "fake",
I mean I don't care what the unit number is.
- if the "fake" cdev does not exist, create a /dev/mx_fake.%d,
using the "fake" unit number via make_dev()
- using the cdev obtained from either clone_create(), or make_dev(),
set (*cdev)->si_drv1 to the "real" unit number so my open
routine knows what to do.
Any idea what I'm doing wrong?
Thanks for the help,
Drew
static void
mx_clone(void *arg, char *name, int namelen, struct cdev **cdev)
{
int u, i, privileged, mode, fake_unit, free_cdev;
if (*cdev != NULL) {
/* printf("mx_clone called with non-null struct cdev *??\n");*/
return;
}
if (dev_stdclone(name, NULL, "mxp", &u)) {
privileged = 1;
mode = 0600;
} else if (dev_stdclone(name, NULL, "mx", &u)) {
privileged = 0;
mode = 0666;
} else {/* Don't recognize the name */
return;
}
if (u >= mx_num_instances)
return; /* unit too large */
if (privileged && suser(curthread))
return; /* EPERM */
/* Now we iterate over our clone list. We start at index 0, and
keep going until we find a free clone. We know the clone is free
because either the cdev is null (in which case it was never
allocated, and no /dev/mx_fake.%d entry exists) or the cdev is
non-null, and its si_drv1 field is null (which means that it has
been closed by another process, and a /dev/mx_fake.%d exists).
Its important to find priviliged devices, so we always search
only odd units when we want a priviliged device.
*/
fake_unit = 0 + privileged;
do {
i = clone_create(&mx_clones, &mx_cdevsw, &fake_unit, cdev, 0);
free_cdev = i || ((*cdev)->si_drv1 == NULL);
#if 1
printf("dev: %d. i: %d", fake_unit, i);
if (i == 0)
printf(" drv1: %p", (*cdev)->si_drv1);
else
printf(" drv1: NULL");
printf(" Free = %d\n", free_cdev);
#endif
if (!free_cdev)
fake_unit+=2;
} while (!free_cdev);
if (i) {
/* need to allocate a new /dev/mx_fake.%d device node */
*cdev = make_dev(&mx_cdevsw, unit2minor(fake_unit),
UID_ROOT, GID_WHEEL,
mode, "mx_fake.%d", fake_unit);
}
if (*cdev != NULL) {
/* Treat si_drv1 like a bitfield. Low bit is "in use" flag,
second bit is privileged bit, remainder is the real unit that
the opener requested */
mx_always_assert((*cdev)->si_drv1 == NULL);
(*cdev)->si_drv1 = (void *)(uintptr_t)(1 | (privileged << 1) | (u << 2));
(*cdev)->si_drv2 = NULL;
}
}
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