[PATCH] Markers : documentation fix teardown

[Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>]

Document the need for a marker_synchronize_unregister() before the end of exit()
to make sure every probe callers have exited the non preemptible section and
thus are not executing the probe code anymore.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Ingo Molnar <mingo@elte.hu>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: akpm@linux-foundation.org
CC: "Frank Ch. Eigler" <fche@redhat.com>
---
 Documentation/markers.txt |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Index: linux-2.6-lttng/Documentation/markers.txt
===================================================================
--- linux-2.6-lttng.orig/Documentation/markers.txt	2008-07-31 09:11:13.000000000 -0400
+++ linux-2.6-lttng/Documentation/markers.txt	2008-07-31 09:20:57.000000000 -0400
@@ -50,10 +50,12 @@ Connecting a function (probe) to a marke
 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 and make
-sure there is no caller left using the probe when it returns. Probe removal is
-preempt-safe because preemption is disabled around the probe call. See the
-"Probe example" section below for a sample probe module.
+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.
 
 The marker mechanism supports inserting multiple instances of the same marker.
 Markers can be put in inline functions, inlined static functions, and
-- 
Mathieu Desnoyers
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