path: root/samples
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authorMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>2008-02-13 15:03:37 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-13 16:21:20 -0800
commitfb40bd78b0f91b274879cf5db8facd1e04b6052e (patch)
tree2347ccb5ad07f58ab5a4eb41174bb7b54d5f0c5b /samples
parent9170d2f6e1dc4d79650fbf492d1cd45291c66504 (diff)
Linux Kernel Markers: support multiple probes
RCU style multiple probes support for the Linux Kernel Markers. Common case (one probe) is still fast and does not require dynamic allocation or a supplementary pointer dereference on the fast path. - Move preempt disable from the marker site to the callback. Since we now have an internal callback, move the preempt disable/enable to the callback instead of the marker site. Since the callback change is done asynchronously (passing from a handler that supports arguments to a handler that does not setup the arguments is no arguments are passed), we can safely update it even if it is outside the preempt disable section. - Move probe arm to probe connection. Now, a connected probe is automatically armed. Remove MARK_MAX_FORMAT_LEN, unused. This patch modifies the Linux Kernel Markers API : it removes the probe "arm/disarm" and changes the probe function prototype : it now expects a va_list * instead of a "...". If we want to have more than one probe connected to a marker at a given time (LTTng, or blktrace, ssytemtap) then we need this patch. Without it, connecting a second probe handler to a marker will fail. It allow us, for instance, to do interesting combinations : Do standard tracing with LTTng and, eventually, to compute statistics with SystemTAP, or to have a special trigger on an event that would call a systemtap script which would stop flight recorder tracing. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Cc: Christoph Hellwig <hch@infradead.org> Cc: Mike Mason <mmlnx@us.ibm.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: David Smith <dsmith@redhat.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: "Frank Ch. Eigler" <fche@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'samples')
1 files changed, 9 insertions, 16 deletions
diff --git a/samples/markers/probe-example.c b/samples/markers/probe-example.c
index a36797535615..c8e099d4d1fd 100644
--- a/samples/markers/probe-example.c
+++ b/samples/markers/probe-example.c
@@ -20,31 +20,27 @@ struct probe_data {
marker_probe_func *probe_func;
-void probe_subsystem_event(const struct marker *mdata, void *private,
- const char *format, ...)
+void probe_subsystem_event(void *probe_data, void *call_data,
+ const char *format, va_list *args)
- va_list ap;
/* Declare args */
unsigned int value;
const char *mystr;
/* Assign args */
- va_start(ap, format);
- value = va_arg(ap, typeof(value));
- mystr = va_arg(ap, typeof(mystr));
+ value = va_arg(*args, typeof(value));
+ mystr = va_arg(*args, typeof(mystr));
/* Call printk */
- printk(KERN_DEBUG "Value %u, string %s\n", value, mystr);
+ printk(KERN_INFO "Value %u, string %s\n", value, mystr);
/* or count, check rights, serialize data in a buffer */
- va_end(ap);
atomic_t eventb_count = ATOMIC_INIT(0);
-void probe_subsystem_eventb(const struct marker *mdata, void *private,
- const char *format, ...)
+void probe_subsystem_eventb(void *probe_data, void *call_data,
+ const char *format, va_list *args)
/* Increment counter */
@@ -72,10 +68,6 @@ static int __init probe_init(void)
if (result)
printk(KERN_INFO "Unable to register probe %s\n",
- result = marker_arm(probe_array[i].name);
- if (result)
- printk(KERN_INFO "Unable to arm probe %s\n",
- probe_array[i].name);
return 0;
@@ -85,7 +77,8 @@ static void __exit probe_fini(void)
int i;
for (i = 0; i < ARRAY_SIZE(probe_array); i++)
- marker_probe_unregister(probe_array[i].name);
+ marker_probe_unregister(probe_array[i].name,
+ probe_array[i].probe_func, &probe_array[i]);
printk(KERN_INFO "Number of event b : %u\n",