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authorMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>2008-11-14 17:47:48 -0500
committerIngo Molnar <mingo@elte.hu>2008-11-16 09:01:37 +0100
commit8fd88d159031bd238dad1d7186a2030b9f9349de (patch)
treef5ab2ddfd747ee0dd6e4e9555671ff6b7d0dca0b /Documentation
parent7e066fb870fcd1025ec3ba7bbde5d541094f4ce1 (diff)
tracepoints: documentation fix for teardown
Impact: documentation update Need a tracepoint_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> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/tracepoints.txt10
1 files changed, 6 insertions, 4 deletions
diff --git a/Documentation/tracepoints.txt b/Documentation/tracepoints.txt
index e8ad47b437f..93cd90e89cc 100644
--- a/Documentation/tracepoints.txt
+++ b/Documentation/tracepoints.txt
@@ -70,10 +70,12 @@ Where :
Connecting a function (probe) to a tracepoint is done by providing a probe
(function to call) for the specific tracepoint through
register_trace_subsys_eventname(). Removing a probe is done through
-unregister_trace_subsys_eventname(); it will remove the probe 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.
+unregister_trace_subsys_eventname(); it will remove 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 tracepoint mechanism supports inserting multiple instances of the same
tracepoint, but a single definition must be made of a given tracepoint name over