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authorLinus Torvalds <torvalds@linux-foundation.org>2008-12-28 12:21:10 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2008-12-28 12:21:10 -0800
commitb0f4b285d7ed174804658539129a834270f4829a (patch)
treebe7f8dca58075aba2c6a137fcfd4d44c5c333efc /Documentation/markers.txt
parentbe9c5ae4eeec2e85527e95647348b8ea4eb25128 (diff)
parent5250d329e38cdf7580faeb9c53c17d3588d7d19c (diff)
Merge branch 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (241 commits) sched, trace: update trace_sched_wakeup() tracing/ftrace: don't trace on early stage of a secondary cpu boot, v3 Revert "x86: disable X86_PTRACE_BTS" ring-buffer: prevent false positive warning ring-buffer: fix dangling commit race ftrace: enable format arguments checking x86, bts: memory accounting x86, bts: add fork and exit handling ftrace: introduce tracing_reset_online_cpus() helper tracing: fix warnings in kernel/trace/trace_sched_switch.c tracing: fix warning in kernel/trace/trace.c tracing/ring-buffer: remove unused ring_buffer size trace: fix task state printout ftrace: add not to regex on filtering functions trace: better use of stack_trace_enabled for boot up code trace: add a way to enable or disable the stack tracer x86: entry_64 - introduce FTRACE_ frame macro v2 tracing/ftrace: add the printk-msg-only option tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp() x86, bts: correctly report invalid bts records ... Fixed up trivial conflict in scripts/recordmcount.pl due to SH bits being already partly merged by the SH merge.
Diffstat (limited to 'Documentation/markers.txt')
-rw-r--r--Documentation/markers.txt29
1 files changed, 24 insertions, 5 deletions
diff --git a/Documentation/markers.txt b/Documentation/markers.txt
index 089f6138fcd..d2b3d0e91b2 100644
--- a/Documentation/markers.txt
+++ b/Documentation/markers.txt
@@ -51,11 +51,16 @@ 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.
-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.
+
+marker_synchronize_unregister() must be called between probe unregistration and
+the first occurrence of
+- the end of module exit function,
+ to make sure there is no caller left using the probe;
+- the free of any resource used by the probes,
+ to make sure the probes wont be accessing invalid data.
+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
@@ -70,6 +75,20 @@ a printk warning which identifies the inconsistency:
"Format mismatch for probe probe_name (format), marker (format)"
+Another way to use markers is to simply define the marker without generating any
+function call to actually call into the marker. This is useful in combination
+with tracepoint probes in a scheme like this :
+
+void probe_tracepoint_name(unsigned int arg1, struct task_struct *tsk);
+
+DEFINE_MARKER_TP(marker_eventname, tracepoint_name, probe_tracepoint_name,
+ "arg1 %u pid %d");
+
+notrace void probe_tracepoint_name(unsigned int arg1, struct task_struct *tsk)
+{
+ struct marker *marker = &GET_MARKER(kernel_irq_entry);
+ /* write data to trace buffers ... */
+}
* Probe / marker example