tracepoints: fix reentrancy

The tracepoints had the same problem markers did have wrt reentrancy. Apply a
similar fix using a rcu_barrier after each tracepoint mutex lock.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 0 deletions

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index db39961a0d03..f2b7c28a4708 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -356,6 +356,8 @@ int tracepoint_probe_register(const char *name, void *probe)
         mutex_lock(&tracepoints_mutex);
         entry = get_tracepoint(name);
         WARN_ON(!entry);
+        if (entry->rcu_pending)
+                rcu_barrier_sched();
         tracepoint_entry_free_old(entry, old);
 end:
         mutex_unlock(&tracepoints_mutex);
@@ -392,6 +394,8 @@ int tracepoint_probe_unregister(const char *name, void *probe)
         entry = get_tracepoint(name);
         if (!entry)
                 goto end;
+        if (entry->rcu_pending)
+                rcu_barrier_sched();
         tracepoint_entry_free_old(entry, old);
         remove_tracepoint(name);        /* Ignore busy error message */
         ret = 0;