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| -rw-r--r-- | Documentation/trace/ftrace-uses.rst | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/trace/ftrace-uses.rst b/Documentation/trace/ftrace-uses.rst index 5981d5691745..f7d98ae5b885 100644 --- a/Documentation/trace/ftrace-uses.rst +++ b/Documentation/trace/ftrace-uses.rst @@ -116,6 +116,8 @@ called by a callback may also be traced, and call that same callback, recursion protection must be used. There are two helper functions that can help in this regard. If you start your code with: +.. code-block:: c + int bit; bit = ftrace_test_recursion_trylock(ip, parent_ip); @@ -124,6 +126,8 @@ can help in this regard. If you start your code with: and end it with: +.. code-block:: c + ftrace_test_recursion_unlock(bit); The code in between will be safe to use, even if it ends up calling a @@ -145,6 +149,8 @@ protection, it is best to make sure that RCU is "watching", otherwise that data or critical section will not be protected as expected. In this case add: +.. code-block:: c + if (!rcu_is_watching()) return; |