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-rw-r--r--Documentation/markers.txt15
-rw-r--r--include/linux/marker.h6
2 files changed, 14 insertions, 7 deletions
diff --git a/Documentation/markers.txt b/Documentation/markers.txt
index 6d275e4ef385..d2b3d0e91b26 100644
--- a/Documentation/markers.txt
+++ b/Documentation/markers.txt
@@ -51,11 +51,16 @@ to call) for the specific marker through marker_probe_register() and can be
51activated by calling marker_arm(). Marker deactivation can be done by calling 51activated by calling marker_arm(). Marker deactivation can be done by calling
52marker_disarm() as many times as marker_arm() has been called. Removing a probe 52marker_disarm() as many times as marker_arm() has been called. Removing a probe
53is done through marker_probe_unregister(); it will disarm the probe. 53is done through marker_probe_unregister(); it will disarm the probe.
54marker_synchronize_unregister() must be called before the end of the module exit 54
55function to make sure there is no caller left using the probe. This, and the 55marker_synchronize_unregister() must be called between probe unregistration and
56fact that preemption is disabled around the probe call, make sure that probe 56the first occurrence of
57removal and module unload are safe. See the "Probe example" section below for a 57- the end of module exit function,
58sample probe module. 58 to make sure there is no caller left using the probe;
59- the free of any resource used by the probes,
60 to make sure the probes wont be accessing invalid data.
61This, and the fact that preemption is disabled around the probe call, make sure
62that probe removal and module unload are safe. See the "Probe example" section
63below for a sample probe module.
59 64
60The marker mechanism supports inserting multiple instances of the same marker. 65The marker mechanism supports inserting multiple instances of the same marker.
61Markers can be put in inline functions, inlined static functions, and 66Markers can be put in inline functions, inlined static functions, and
diff --git a/include/linux/marker.h b/include/linux/marker.h
index 34c14bc957f5..b85e74ca782f 100644
--- a/include/linux/marker.h
+++ b/include/linux/marker.h
@@ -211,8 +211,10 @@ extern void *marker_get_private_data(const char *name, marker_probe_func *probe,
211 211
212/* 212/*
213 * marker_synchronize_unregister must be called between the last marker probe 213 * marker_synchronize_unregister must be called between the last marker probe
214 * unregistration and the end of module exit to make sure there is no caller 214 * unregistration and the first one of
215 * executing a probe when it is freed. 215 * - the end of module exit function
216 * - the free of any resource used by the probes
217 * to ensure the code and data are valid for any possibly running probes.
216 */ 218 */
217#define marker_synchronize_unregister() synchronize_sched() 219#define marker_synchronize_unregister() synchronize_sched()
218 220