Hello,
it seems like there is a problem with node reference counts. I have a
test program, that instantiates a chain of nodes like this:
ng_atm -----------> ng_sscop --------------> ng_sscf ---------> ng_socket
| ^
+--------------------------------------+
the ng_sscf and ng_sscop node's disconnect procedures call
ng_rmnode_self() in the case that the hook count drops to zero and the
node is still valid. The shutdown methods free private memory and call
NG_NODE_UNREF.
When destroying the above graph I first send a shutdown to the ng_sscf
node and then to the ng_sscop node. The sscf node disappears as expected
leaving the sscop node with two hooks. The shutdown of that node first
disconnects those two hooks and then calls the shutdown method of
ng_sscop. Everything is fine, except that I find the following lines in
/var/log/messages:
Jan 29 17:26:21 beagle /boot/kernel/kernel: disconnect 0xc2c54980 from 0xc2c94d00
(invalid) refs=3 flags=9
Jan 29 17:26:21 beagle /boot/kernel/kernel: ng_sscop_shutdown: 0xc2c94d00 refs=2
flags=9
Jan 29 17:26:21 beagle /boot/kernel/kernel: Accessing freed node node: ID [7]: type
'sscop', 0 hooks, flags 0x9, 0 refs, :
Jan 29 17:26:21 beagle /boot/kernel/kernel: Last active @
/usr/src/sys/modules/netgraph/netgraph/../../../netgraph/ng_base.c, line 735
Jan 29 17:26:21 beagle /boot/kernel/kernel: problem discovered at file
/usr/src/sys/modules/netgraph/netgraph/../../../netgraph/ng_base.c, line 2436
The first two lines come from the sscop node, the other from ng_base.
I have put a couple of printf()s into ng_base to understand what happens but
could not find the problem. I have the feeling, that the reference count
when entering ng_sscop_shutdown should be rather 3 than 2: one held by the
item from which the shutdown is executed and which is UNREFed in line 2436.
One extra reference from the ng_rmnode function and the reference, that
is UNREFed in the ng_sscop_shutdown method. But I may be wrong.
So what is the problem?
harti
--
harti brandt,
http://www.fokus.gmd.de/research/cc/cats/employees/hartmut.brandt/private
[EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED]
To Unsubscribe: send mail to [EMAIL PROTECTED]
with "unsubscribe freebsd-net" in the body of the message
