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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>
This commit is contained in:
Mathieu Desnoyers 2008-11-14 17:47:48 -05:00 committed by Ingo Molnar
parent 7e066fb870
commit 8fd88d1590
1 changed files with 6 additions and 4 deletions
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10
Documentation/tracepoints.txt
View File

@ -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