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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 03:01:37 -0500
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 e8ad47b437f3..93cd90e89cc1 100644
--- a/Documentation/tracepoints.txt
+++ b/Documentation/tracepoints.txt
@@ -70,10 +70,12 @@ Where :
70Connecting a function (probe) to a tracepoint is done by providing a probe 70Connecting a function (probe) to a tracepoint is done by providing a probe
71(function to call) for the specific tracepoint through 71(function to call) for the specific tracepoint through
72register_trace_subsys_eventname(). Removing a probe is done through 72register_trace_subsys_eventname(). Removing a probe is done through
73unregister_trace_subsys_eventname(); it will remove the probe sure there is no 73unregister_trace_subsys_eventname(); it will remove the probe.
74caller left using the probe when it returns. Probe removal is preempt-safe 74marker_synchronize_unregister() must be called before the end of the module exit
75because preemption is disabled around the probe call. See the "Probe example" 75function to make sure there is no caller left using the probe. This, and the
76section below for a sample probe module. 76fact that preemption is disabled around the probe call, make sure that probe
77removal and module unload are safe. See the "Probe example" section below for a
78sample probe module.
77 79
78The tracepoint mechanism supports inserting multiple instances of the same 80The tracepoint mechanism supports inserting multiple instances of the same
79tracepoint, but a single definition must be made of a given tracepoint name over 81tracepoint, but a single definition must be made of a given tracepoint name over