src/patches/suse-2.6.27.25/patches.trace/tracepoints-documentation-fix-teardown.patch

   1 From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
   2 Subject: Tracepoints : documentation fix teardown
   3
   4 Need a tracepoint_synchronize_unregister() before the end of exit() to make sure
   5 every probe callers have exited the non preemptible section and thus are not
   6 executing the probe code anymore.
   7
   8 Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
   9 CC: Rusty Russell <rusty@rustcorp.com.au>
  10 CC: "Frank Ch. Eigler" <fche@redhat.com>
  11 CC: Ingo Molnar <mingo@elte.hu>
  12 CC: Peter Zijlstra <peterz@infradead.org>
  13 CC: Steven Rostedt <rostedt@goodmis.org>
  14 Acked-by: Jan Blunck <jblunck@suse.de>
  15 ---
  16  Documentation/tracepoints.txt |   10 ++++++----
  17  1 file changed, 6 insertions(+), 4 deletions(-)
  18
  19 Index: linux-2.6-lttng/Documentation/tracepoints.txt
  20 ===================================================================
  21 --- linux-2.6-lttng.orig/Documentation/tracepoints.txt  2008-07-31 09:22:56.000000000 -0400
  22 +++ linux-2.6-lttng/Documentation/tracepoints.txt       2008-07-31 09:24:54.000000000 -0400
  23 @@ -68,10 +68,12 @@ Where :
  24  Connecting a function (probe) to a tracepoint is done by providing a probe
  25  (function to call) for the specific tracepoint through
  26  register_trace_subsys_eventname().  Removing a probe is done through
  27 -unregister_trace_subsys_eventname(); it will remove the probe sure there is no
  28 -caller left using the probe when it returns. Probe removal is preempt-safe
  29 -because preemption is disabled around the probe call. See the "Probe example"
  30 -section below for a sample probe module.
  31 +unregister_trace_subsys_eventname(); it will remove the probe.
  32 +marker_synchronize_unregister() must be called before the end of the module exit
  33 +function to make sure there is no caller left using the probe. This, and the
  34 +fact that preemption is disabled around the probe call, make sure that probe
  35 +removal and module unload are safe. See the "Probe example" section below for a
  36 +sample probe module.
  37
  38  The tracepoint mechanism supports inserting multiple instances of the same
  39  tracepoint, but a single definition must be made of a given tracepoint name over