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. Impact: documentation update. Signed-off-by: Mathieu Desnoyers CC: Rusty Russell CC: "Frank Ch. Eigler" CC: Ingo Molnar CC: Lai Jiangshan CC: Peter Zijlstra CC: Steven Rostedt --- Documentation/tracepoints.txt | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) Index: linux-2.6-lttng/Documentation/tracepoints.txt =================================================================== --- linux-2.6-lttng.orig/Documentation/tracepoints.txt 2008-11-14 17:18:59.000000000 -0500 +++ linux-2.6-lttng/Documentation/tracepoints.txt 2008-11-14 17:19:05.000000000 -0500 @@ -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 -- Mathieu Desnoyers 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/