markers: documentation fix for teardown

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>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Mathieu Desnoyers 2008-09-29 11:10:34 -04:00 committed by Ingo Molnar
parent 531d297569
commit 91a8d46c47

View file

@ -50,10 +50,12 @@ Connecting a function (probe) to a marker is done by providing a probe (function
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