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authorWu Fengguang <fengguang.wu@intel.com>2008-11-27 16:14:44 +0800
committerIngo Molnar <mingo@elte.hu>2008-11-28 16:47:41 +0100
commita838c2ec6ea1f18431da74dfe4978c57355b95f3 (patch)
treec51852ff62ec383c27e21f318f5e3180f141b885 /Documentation
parentc7cc77307669336a08928ab8668bdb3f3bcc021b (diff)
markers: comment marker_synchronize_unregister() on data dependency
Add document and comments on marker_synchronize_unregister(): it should be called before freeing resources that the probes depend on. Based on comments from Lai Jiangshan and Mathieu Desnoyers. Signed-off-by: Wu Fengguang <wfg@linux.intel.com> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/markers.txt15
1 files changed, 10 insertions, 5 deletions
diff --git a/Documentation/markers.txt b/Documentation/markers.txt
index 6d275e4ef38..d2b3d0e91b2 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
activated by calling marker_arm(). Marker deactivation can be done by calling
marker_disarm() as many times as marker_arm() has been called. Removing a probe
is done through marker_probe_unregister(); it will disarm the probe.
-marker_synchronize_unregister() must be called before the end of the module exit
-function to make sure there is no caller left using the probe. This, and the
-fact that preemption is disabled around the probe call, make sure that probe
-removal and module unload are safe. See the "Probe example" section below for a
-sample probe module.
+
+marker_synchronize_unregister() must be called between probe unregistration and
+the first occurrence of
+- the end of module exit function,
+ to make sure there is no caller left using the probe;
+- the free of any resource used by the probes,
+ to make sure the probes wont be accessing invalid data.
+This, and the fact that preemption is disabled around the probe call, make sure
+that probe removal and module unload are safe. See the "Probe example" section
+below for a sample probe module.
The marker mechanism supports inserting multiple instances of the same marker.
Markers can be put in inline functions, inlined static functions, and