[PATCH 0/2] sysctl: lockdep support.

From: Eric W. Biederman
Date: Sat Mar 21 2009 - 03:41:24 EST



The problem: There is a class of deadlocks that we currently
have in the kernel that lockdep does not recognize.

In particular with the network stack we can have:

rtnl_lock(); use_table();
unregister_netdevice(); rtnl_lock();
unregister_sysctl_table(); ....
wait_for_completion(); rtnl_lock();
.... unuse_table()
rtnl_unlock(); complete();



Where we never make it to the lines labled ....

My patch following patches treats the sysctl use count as a read/writer
lock for purposes of lockdep.

The code works but I'm not certain I have plugged into lockdep quite
correctly.

Eric

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