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tracing: Fix free of probe entry by calling call_rcu_sched() 

Because function tracing is very invasive, and can even trace
calls to rcu_read_lock(), RCU access in function tracing is done
with preempt_disable_notrace(). This requires a synchronize_sched()
for updates and not a synchronize_rcu().

Function probes (traceon, traceoff, etc) must be freed after
a synchronize_sched() after its entry has been removed from the
hash. But call_rcu() is used. Fix this by using call_rcu_sched().

Also fix the usage to use hlist_del_rcu() instead of hlist_del().

Cc: stable@vger.kernel.org
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2013-03-13 11:15:19 -04:00 committed by Steven Rostedt
parent 2721e72dd1
commit 740466bc89
1 changed files with 2 additions and 2 deletions
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4
kernel/trace/ftrace.c
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@ -3108,8 +3108,8 @@ __unregister_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
continue;
}
hlist_del(&entry->node);
call_rcu(&entry->rcu, ftrace_free_entry_rcu);
hlist_del_rcu(&entry->node);
call_rcu_sched(&entry->rcu, ftrace_free_entry_rcu);
}
}
__disable_ftrace_function_probe();