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Diffstat (limited to 'Documentation/trace/ftrace-uses.rst')
| -rw-r--r-- | Documentation/trace/ftrace-uses.rst | 60 |
1 files changed, 30 insertions, 30 deletions
diff --git a/Documentation/trace/ftrace-uses.rst b/Documentation/trace/ftrace-uses.rst index 8494a801d341..3aed560a12ee 100644 --- a/Documentation/trace/ftrace-uses.rst +++ b/Documentation/trace/ftrace-uses.rst @@ -42,9 +42,9 @@ as well as what protections the callback will perform and not require ftrace to handle. There is only one field that is needed to be set when registering -an ftrace_ops with ftrace:: +an ftrace_ops with ftrace: -.. code-block: c +.. code-block:: c struct ftrace_ops ops = { .func = my_callback_func, @@ -81,12 +81,12 @@ may take some time to finish. The callback function ===================== -The prototype of the callback function is as follows (as of v4.14):: +The prototype of the callback function is as follows (as of v4.14): -.. code-block: c +.. code-block:: c - void callback_func(unsigned long ip, unsigned long parent_ip, - struct ftrace_ops *op, struct pt_regs *regs); + void callback_func(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, struct pt_regs *regs); @ip This is the instruction pointer of the function that is being traced. @@ -176,10 +176,10 @@ Filtering which functions to trace If a callback is only to be called from specific functions, a filter must be set up. The filters are added by name, or ip if it is known. -.. code-block: c +.. code-block:: c - int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf, - int len, int reset); + int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf, + int len, int reset); @ops The ops to set the filter with @@ -202,9 +202,9 @@ See Filter Commands in :file:`Documentation/trace/ftrace.txt`. To just trace the schedule function:: -.. code-block: c +.. code-block:: c - ret = ftrace_set_filter(&ops, "schedule", strlen("schedule"), 0); + ret = ftrace_set_filter(&ops, "schedule", strlen("schedule"), 0); 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 @@ -212,17 +212,17 @@ with new functions defined by @buf, have @reset be non-zero. To remove all the filtered functions and trace all functions:: -.. code-block: c +.. code-block:: c - ret = ftrace_set_filter(&ops, NULL, 0, 1); + ret = ftrace_set_filter(&ops, NULL, 0, 1); Sometimes more than one function has the same name. To trace just a specific function in this case, ftrace_set_filter_ip() can be used. -.. code-block: c +.. code-block:: c - ret = ftrace_set_filter_ip(&ops, ip, 0, 0); + ret = ftrace_set_filter_ip(&ops, ip, 0, 0); Although the ip must be the address where the call to fentry or mcount is located in the function. This function is used by perf and kprobes that @@ -237,10 +237,10 @@ be called by any function. An empty "notrace" list means to allow all functions defined by the filter to be traced. -.. code-block: c +.. code-block:: c - int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf, - int len, int reset); + int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf, + int len, int reset); This takes the same parameters as ftrace_set_filter() but will add the functions it finds to not be traced. This is a separate list from the @@ -251,7 +251,7 @@ that match @buf to it. Clearing the "notrace" list is the same as clearing the filter list -.. code-block: c +.. code-block:: c ret = ftrace_set_notrace(&ops, NULL, 0, 1); @@ -264,29 +264,29 @@ If a filter is in place, and the @reset is non-zero, and @buf contains a matching glob to functions, the switch will happen during the time of the ftrace_set_filter() call. At no time will all functions call the callback. -.. code-block: c +.. code-block:: c - ftrace_set_filter(&ops, "schedule", strlen("schedule"), 1); + ftrace_set_filter(&ops, "schedule", strlen("schedule"), 1); - register_ftrace_function(&ops); + register_ftrace_function(&ops); - msleep(10); + msleep(10); - ftrace_set_filter(&ops, "try_to_wake_up", strlen("try_to_wake_up"), 1); + ftrace_set_filter(&ops, "try_to_wake_up", strlen("try_to_wake_up"), 1); is not the same as: -.. code-block: c +.. code-block:: c - ftrace_set_filter(&ops, "schedule", strlen("schedule"), 1); + ftrace_set_filter(&ops, "schedule", strlen("schedule"), 1); - register_ftrace_function(&ops); + register_ftrace_function(&ops); - msleep(10); + msleep(10); - ftrace_set_filter(&ops, NULL, 0, 1); + ftrace_set_filter(&ops, NULL, 0, 1); - ftrace_set_filter(&ops, "try_to_wake_up", strlen("try_to_wake_up"), 0); + ftrace_set_filter(&ops, "try_to_wake_up", strlen("try_to_wake_up"), 0); As the latter will have a short time where all functions will call the callback, between the time of the reset, and the time of the |