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trace doc: add ftrace-uses.rst to doc tree 

Add ftrace-uses.rst into Sphinx TOC tree. Few format issues are fixed.

Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Changbin Du <changbin.du@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
hifive-unleashed-5.1
Changbin Du 2018-02-17 13:39:36 +08:00 committed by Jonathan Corbet
parent fcdeddc9fd
commit b3fdd1f92c
2 changed files with 13 additions and 11 deletions
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23
Documentation/trace/ftrace-uses.rst
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@ -21,13 +21,14 @@ how to use ftrace to implement your own function callbacks.
The ftrace context
==================
.. warning::
WARNING: The ability to add a callback to almost any function within the
kernel comes with risks. A callback can be called from any context
(normal, softirq, irq, and NMI). Callbacks can also be called just before
going to idle, during CPU bring up and takedown, or going to user space.
This requires extra care to what can be done inside a callback. A callback
can be called outside the protective scope of RCU.
The ability to add a callback to almost any function within the
kernel comes with risks. A callback can be called from any context
(normal, softirq, irq, and NMI). Callbacks can also be called just before
going to idle, during CPU bring up and takedown, or going to user space.
This requires extra care to what can be done inside a callback. A callback
can be called outside the protective scope of RCU.
The ftrace infrastructure has some protections agains recursions and RCU
but one must still be very careful how they use the callbacks.
@ -54,15 +55,15 @@ an ftrace_ops with ftrace:
Both .flags and .private are optional. Only .func is required.
To enable tracing call::
To enable tracing call:
.. c:function:: register_ftrace_function(&ops);
To disable tracing call::
To disable tracing call:
.. c:function:: unregister_ftrace_function(&ops);
The above is defined by including the header::
The above is defined by including the header:
.. c:function:: #include <linux/ftrace.h>
@ -200,7 +201,7 @@ match a specific pattern.
See Filter Commands in :file:`Documentation/trace/ftrace.txt`.
To just trace the schedule function::
To just trace the schedule function:
.. code-block:: c
@ -210,7 +211,7 @@ To add more functions, call the ftrace_set_filter() more than once with the
@reset parameter set to zero. To remove the current filter set and replace it
with new functions defined by @buf, have @reset be non-zero.
To remove all the filtered functions and trace all functions::
To remove all the filtered functions and trace all functions:
.. code-block:: c

1
Documentation/trace/index.rst
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@ -6,3 +6,4 @@ Linux Tracing Technologies
:maxdepth: 2
ftrace-design
ftrace-uses