Re: [bug] hung bootup in various drivers, was: "2.6.21-rc5: known regressions"


* Greg KH <gregkh@xxxxxxx> wrote:

BUG: at drivers/base/driver.c:187 driver_unregister()
[<c0105ff9>] show_trace_log_lvl+0x19/0x2e
[<c01063e2>] show_trace+0x12/0x14
[<c01063f8>] dump_stack+0x14/0x16
[<c063f7e6>] driver_unregister+0x3d/0x43
[<c0488048>] pci_unregister_driver+0x10/0x5f
[<c1b5f7c7>] slgt_init+0x9b/0x1ca
[<c1b31a2d>] init+0x15d/0x2bd
[<c0105bc3>] kernel_thread_helper+0x7/0x10

Yes, we should allow the ability to call unregister_driver from within
the module_init function.

But I don't understand what is causing you to see this problem. Who
is holding the reference on the struct device at this point in time?
Is it the fact that userspace has some files open and it hasn't
released them yet?

at least in the slgt_init() case the affected codepath is trivial:

if ((rc = pci_register_driver(&pci_driver)) < 0) {
printk("%s pci_register_driver error=%d\n", driver_name, rc);
return rc;
}
pci_registered = 1;

if (!slgt_device_list) {
printk("%s no devices found\n",driver_name);
pci_unregister_driver(&pci_driver);
return -ENODEV;

slgt_device_list is NULL because no matching PCI ID is on my system (i
dont have this hardware), so the ->probe() function did not get called
at all.

i.e. a pure pci_register_driver() + pci_unregister_driver() sequence
seems to cause a hang. I.e. it seems to be a pure driver-base-core
matter.

Ingo
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