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tracing: Add hook to function tracing for other subsystems to use

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Currently Function traces can be only exported to the ring buffer. This
adds a trace_export concept which can process traces and export
them to a registered destination as an addition to the current
one that outputs to Ftrace - i.e. ring buffer.

In this way, if we want function traces to be sent to other destinations
rather than only to the ring buffer, we just need to register a new
trace_export and implement its own .write() function for writing traces to
storage.

With this patch, only function tracing (trace type is TRACE_FN)
is supported.

Link: http://lkml.kernel.org/r/1479715043-6534-2-git-send-email-zhang.chunyan@linaro.org

Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Chunyan Zhang
2016-11-21 15:57:18 +08:00
committed by Steven Rostedt
parent 153aae5f99
commit 478409dd68
2 changed files with 156 additions and 1 deletions
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28
include/linux/trace.h Normal file
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@@ -0,0 +1,28 @@
#ifndef _LINUX_TRACE_H
#define _LINUX_TRACE_H
#ifdef CONFIG_TRACING
/*
* The trace export - an export of Ftrace output. The trace_export
* can process traces and export them to a registered destination as
* an addition to the current only output of Ftrace - i.e. ring buffer.
*
* If you want traces to be sent to some other place rather than ring
* buffer only, just need to register a new trace_export and implement
* its own .write() function for writing traces to the storage.
*
* next - pointer to the next trace_export
* write - copy traces which have been delt with ->commit() to
* the destination
*/
struct trace_export {
struct trace_export __rcu *next;
void (*write)(const void *, unsigned int);
};
int register_ftrace_export(struct trace_export *export);
int unregister_ftrace_export(struct trace_export *export);
#endif /* CONFIG_TRACING */
#endif /* _LINUX_TRACE_H */