Messages in this thread Patch in this message | | | Date | Fri, 14 Nov 2008 17:47:48 -0500 | From | Mathieu Desnoyers <> | Subject | [patch 15/16] Tracepoints : documentation fix teardown |
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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 <mathieu.desnoyers@polymtl.ca> CC: Rusty Russell <rusty@rustcorp.com.au> CC: "Frank Ch. Eigler" <fche@redhat.com> CC: Ingo Molnar <mingo@elte.hu> CC: Lai Jiangshan <laijs@cn.fujitsu.com> CC: Peter Zijlstra <peterz@infradead.org> CC: Steven Rostedt <rostedt@goodmis.org> --- 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
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