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![]() I have been experimenting with loadable protocol modules, and ran into several issues with module reference counting. The first issue was that __module_get failed at the BUG_ON check at the top of the routine (checking that my module reference count was not zero) when I created the first socket. When sk_alloc() is called, my module reference count was still 0. When I looked at why sctp didn't have this problem, I discovered that sctp creates a control socket during module init (when the module ref count is not 0), which keeps the reference count non-zero. This section has been updated to address the point Stephen raised about checking the return value of try_module_get(). The next problem arose when my socket init routine returned an error. This resulted in my module reference count being decremented below 0. My socket ops->release routine was also being called. The issue here is that sock_release() calls the ops->release routine and decrements the ref count if sock->ops is not NULL. Since the socket probably didn't get correctly initialized, this should not be done, so we will set sock->ops to NULL because we will not call try_module_get(). While searching for another bug, I also noticed that sys_accept() has a possibility of doing a module_put() when it did not do an __module_get so I re-ordered the call to security_socket_accept(). Signed-off-by: Frank Filz <ffilzlnx@us.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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802 | ||
8021q | ||
appletalk | ||
atm | ||
ax25 | ||
bluetooth | ||
bridge | ||
core | ||
dccp | ||
decnet | ||
econet | ||
ethernet | ||
ieee80211 | ||
ipv4 | ||
ipv6 | ||
ipx | ||
irda | ||
key | ||
lapb | ||
llc | ||
netfilter | ||
netlink | ||
netrom | ||
packet | ||
rose | ||
rxrpc | ||
sched | ||
sctp | ||
sunrpc | ||
unix | ||
wanrouter | ||
x25 | ||
xfrm | ||
compat.c | ||
Kconfig | ||
Makefile | ||
nonet.c | ||
socket.c | ||
sysctl_net.c | ||
TUNABLE |