This patch correct the flaw identified by Pete Zaitcev.
Plus I now fully understand the sysfs oops.
It is not a problem with sysfs, so GregKH rightly ignored me.
A pointer to control_interface->dev is saved in the tty class device
object created by tty_register_device(). This reference is used to
create/destroy sysfs symlinks between the tty class device object and the
control_interface->dev. On disconnect control_interface->dev is released.
tty_unregister_device() is called later when the last tty file desc
is closed. tty_unregister_device() then passes the stale pointer
to sysfs_remove_link() causing the oops if the slab debug is turned on.
So the below patch seems the cleanest way of fixing this.
Patch Description:
Clear acm->tty on last close because the tty layer
releases the tty object at that point.
Use a NULL device with tty_register_device() to prevent
tty layer from creating sysfs entries referencing the usb device.
This prevents oops in sysfs_hash_and_remove when tty_unregister_device
is called after usb device is disconnected during use. By the time
tty_unregister_device is called, the usb device has already been released.
Signed-off-by: Paul Fulghum <[EMAIL PROTECTED]>
--- linux-2.6.16-rc5/drivers/usb/class/cdc-acm.c 2006-02-27
14:40:21.000000000 -0600
+++ b/drivers/usb/class/cdc-acm.c 2006-03-13 12:28:19.000000000 -0600
@@ -515,6 +515,7 @@ static void acm_tty_close(struct tty_str
usb_kill_urb(acm->writeurb);
for (i = 0; i < ACM_NRU; i++)
usb_kill_urb(acm->ru[i].urb);
+ acm->tty = NULL;
} else
acm_tty_unregister(acm);
}
@@ -980,7 +981,7 @@ skip_normal_probe:
usb_driver_claim_interface(&acm_driver, data_interface, acm);
usb_get_intf(control_interface);
- tty_register_device(acm_tty_driver, minor, &control_interface->dev);
+ tty_register_device(acm_tty_driver, minor, NULL);
acm_table[minor] = acm;
usb_set_intfdata (intf, acm);
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