| From | Greg Kroah-Hartman <> | Subject | [ 39/98] tracing: Fix free of probe entry by calling call_rcu_sched() | Date | Tue, 26 Mar 2013 15:42:28 -0700 |
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3.8-stable review patch. If anyone has any objections, please let me know.
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From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
commit 740466bc89ad8bd5afcc8de220f715f62b21e365 upstream.
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().
Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/trace/ftrace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3082,8 +3082,8 @@ __unregister_ftrace_function_probe(char 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();
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