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 CC: Ingo Molnar CC: Rusty Russell CC: akpm@linux-foundation.org CC: "Frank Ch. Eigler" --- 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 Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/