[tip:perf/urgent] tracing: Fix free of probe entry by calling call_rcu_sched()

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Commit-ID:  740466bc89ad8bd5afcc8de220f715f62b21e365
Gitweb:     http://git.kernel.org/tip/740466bc89ad8bd5afcc8de220f715f62b21e365
Author:     Steven Rostedt (Red Hat) <rostedt@xxxxxxxxxxx>
AuthorDate: Wed, 13 Mar 2013 11:15:19 -0400
Committer:  Steven Rostedt <rostedt@xxxxxxxxxxxxxxxxxxxxx>
CommitDate: Wed, 13 Mar 2013 17:57:44 -0400

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@xxxxxxxxxxxxxxx
Cc: Paul McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 kernel/trace/ftrace.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 98ca94a..e6effd0 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -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();
--
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