[PATCH 2/2] Tracepoint API doc update: tracepoint_probe_register() return value

From: Mathieu Desnoyers
Date: Mon Mar 10 2014 - 21:05:34 EST


Describe the return values of tracepoint_probe_register(), including
-ENODEV added by commit:

Author: Steven Rostedt <rostedt@xxxxxxxxxxx>

tracing: Warn if a tracepoint is not set via debugfs

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
CC: Steven Rostedt <rostedt@xxxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
CC: Frederic Weisbecker <fweisbec@xxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/tracepoint.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 49cb94e..0839258 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -378,7 +378,17 @@ tracepoint_add_probe(const char *name, void *probe, void *data)
* @probe: probe handler
* @data: probe private data
*
- * Returns 0 if ok, error value on error.
+ * Returns:
+ * - 0 if the probe was successfully registered, and tracepoint
+ * callsites are currently loaded for that probe,
+ * - -ENODEV if the probe was successfully registered, but no tracepoint
+ * callsite is currently loaded for that probe,
+ * - other negative error value on error.
+ *
+ * When tracepoint_probe_register() returns either 0 or -ENODEV,
+ * parameters @name, @probe, and @data may be used by the tracepoint
+ * infrastructure until the probe is unregistered.
+ *
* The probe address must at least be aligned on the architecture pointer size.
*/
int tracepoint_probe_register(const char *name, void *probe, void *data)
--
1.7.10.4

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