libtraceevent: Document new log functionality

Updated man pages with the new log API and log levels.

Link: https://lore.kernel.org/linux-trace-devel/20210507095022.1079364-5-tz.stoyanov@gmail.com

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

2 files changed, 93 insertions, 0 deletions

diff --git a/Documentation/libtraceevent-log.txt b/Documentation/libtraceevent-log.txt
new file mode 100644
index 0000000..0aee21d
--- /dev/null
+++ b/Documentation/libtraceevent-log.txt
@@ -0,0 +1,90 @@
+libtraceevent(3)
+================
+
+NAME
+----
+tep_set_loglevel - Set log level of the library
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <event-parse.h>*
+
+enum *tep_loglevel* {
+	TEP_LOG_NONE = 0,
+	TEP_LOG_CRITICAL,
+	TEP_LOG_ERROR,
+	TEP_LOG_WARNING,
+	TEP_LOG_INFO,
+	TEP_LOG_DEBUG,
+	TEP_LOG_ALL
+};
+
+int *tep_set_loglevel*(enum tep_loglevel _level_);
+
+--
+DESCRIPTION
+-----------
+The _tep_set_loglevel()_ function sets the level of the library logs that will be printed
+on the console. Library log levels are:
+[verse]
+--
+	_TEP_LOG_NONE_ - Do not print any logs.
+	_TEP_LOG_CRITICAL_ - Print critical logs, problem that may case a crash.
+	_TEP_LOG_ERROR_ - Print error logs, problem that could break the main logic of an API.
+	_TEP_LOG_WARNING_ - Print warnings, problem that could limit the result of an API.
+	_TEP_LOG_INFO_ - Print information about normal execution of an API.
+	_TEP_LOG_DEBUG_ - Print debug information.
+	_TEP_LOG_ALL_ - Print logs from all levels.
+--
+Setting the log level to specific value means that logs from the previous levels will be printed
+too. For example _TEP_LOG_WARNING_ will print any logs with severity _TEP_LOG_WARNING_,
+_TEP_LOG_ERROR_ and _TEP_LOG_CRITICAL_. The default log level is _TEP_LOG_CRITICAL_.
+
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <event-parse.h>
+
+tep_set_loglevel(TEP_LOG_ALL);
+...
+/* call libtraceevent APIs and observe any logs they produce */
+...
+tep_set_loglevel(TEP_LOG_CRITICAL);
+--
+
+FILES
+-----
+[verse]
+--
+*event-parse.h*
+	Header file to include in order to have access to the library APIs.
+*-ltraceevent*
+	Linker switch to add when building a program that uses the library.
+--
+
+SEE ALSO
+--------
+_libtraceevent(3)_, _trace-cmd(1)_
+
+AUTHOR
+------
+[verse]
+--
+*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.
+*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.
+--
+REPORTING BUGS
+--------------
+Report bugs to  <linux-trace-devel@vger.kernel.org>
+
+LICENSE
+-------
+libtraceevent is Free Software licensed under the GNU LGPL 2.1
+
+RESOURCES
+---------
+https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/
diff --git a/Documentation/libtraceevent.txt b/Documentation/libtraceevent.txt
index 3365455..d42b5c9 100644
--- a/Documentation/libtraceevent.txt
+++ b/Documentation/libtraceevent.txt
@@ -127,6 +127,9 @@ Endian related APIs:
 	bool *tep_is_local_bigendian*(struct tep_handle pass:[*]_tep_);
 	void *tep_set_local_bigendian*(struct tep_handle pass:[*]_tep_, enum tep_endian _endian_);
 
+Control library logs:
+	int *tep_set_loglevel*(enum tep_loglevel _level_);
+
 Trace sequences:
 *#include <trace-seq.h>*
 	void *trace_seq_init*(struct trace_seq pass:[*]_s_);