[PATCH v7 03/16] tracing: Add hist trigger handler.action documentation to README

[Tom Zanussi]

From: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>

Add abbreviated documentation for handlers and actions to README.

Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
---
 kernel/trace/trace.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ff1c4b20cd0a..998955dcc3ca 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4686,6 +4686,7 @@ static const char readme_msg[] =
 	"\t            [:size=#entries]\n"
 	"\t            [:pause][:continue][:clear]\n"
 	"\t            [:name=histname1]\n"
+	"\t            [:<handler>.<action>]\n"
 	"\t            [if <filter>]\n\n"
 	"\t    When a matching event is hit, an entry is added to a hash\n"
 	"\t    table using the key(s) and value(s) named, and the value of a\n"
@@ -4727,7 +4728,16 @@ static const char readme_msg[] =
 	"\t    The enable_hist and disable_hist triggers can be used to\n"
 	"\t    have one event conditionally start and stop another event's\n"
 	"\t    already-attached hist trigger.  The syntax is analagous to\n"
-	"\t    the enable_event and disable_event triggers.\n"
+	"\t    the enable_event and disable_event triggers.\n\n"
+	"\t    Hist trigger handlers and actions are executed whenever a\n"
+	"\t    a histogram entry is added or updated.  They take the form:\n\n"
+	"\t        <handler>.<action>\n\n"
+	"\t    The available handlers are:\n\n"
+	"\t        onmatch(matching.event)  - invoke on addition or update\n"
+	"\t        onmax(var)               - invoke if var exceeds current max\n\n"
+	"\t    The available actions are:\n\n"
+	"\t        <synthetic_event>(param list)        - generate synthetic event\n"
+	"\t        save(field,...)                      - save current event fields\n"
 #endif
 ;
 
-- 
2.14.1