Re: [Bluez-devel] Re: Reproducible kernel oops on PPP session start

[Eugene Crosser <crosser@average.org>]

Continuing investigation:

> As far as I can tell from analyzing the dump, and objdump of l2cap.o
> object, BUG() happens when "sk_set_owner(sk, THIS_MODULE);" in
> net/bluetooth/l2cap.c line 353 encounters zero refcount of the module. 
> So, probably somebody incorrectly decreases the l2cap's refcount
> elsewhere...

yes, this seems to be true (and explains the fixed number of attempts). 
Reference count increases by one every time session starts, and
decreases by *two* when it is finished.  Why initial refcount is 5 is
still unclear to me...

root@pccross:/# lsmod|grep l2cap
l2cap                  21952  5 rfcomm
bluetooth              44004  7 rfcomm,l2cap,hci_usb
root@pccross:/# PPP opened

root@pccross:/# lsmod|grep l2cap
l2cap                  21952  6 rfcomm
bluetooth              44004  7 rfcomm,l2cap,hci_usb
root@pccross:/# PPP closed

root@pccross:/# lsmod|grep l2cap
l2cap                  21952  4 rfcomm
bluetooth              44004  7 rfcomm,l2cap,hci_usb
root@pccross:/# PPP opened

root@pccross:/# lsmod|grep l2cap
l2cap                  21952  5 rfcomm
bluetooth              44004  7 rfcomm,l2cap,hci_usb
root@pccross:/# PPP closed

root@pccross:/# lsmod|grep l2cap
l2cap                  21952  3 rfcomm
bluetooth              44004  7 rfcomm,l2cap,hci_usb

Eugene