mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-17 17:24:17 +08:00
fb40bd78b0
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>
92 lines
2.0 KiB
C
92 lines
2.0 KiB
C
/* probe-example.c
|
|
*
|
|
* Connects two functions to marker call sites.
|
|
*
|
|
* (C) Copyright 2007 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
|
|
*
|
|
* This file is released under the GPLv2.
|
|
* See the file COPYING for more details.
|
|
*/
|
|
|
|
#include <linux/sched.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/marker.h>
|
|
#include <asm/atomic.h>
|
|
|
|
struct probe_data {
|
|
const char *name;
|
|
const char *format;
|
|
marker_probe_func *probe_func;
|
|
};
|
|
|
|
void probe_subsystem_event(void *probe_data, void *call_data,
|
|
const char *format, va_list *args)
|
|
{
|
|
/* Declare args */
|
|
unsigned int value;
|
|
const char *mystr;
|
|
|
|
/* Assign args */
|
|
value = va_arg(*args, typeof(value));
|
|
mystr = va_arg(*args, typeof(mystr));
|
|
|
|
/* Call printk */
|
|
printk(KERN_INFO "Value %u, string %s\n", value, mystr);
|
|
|
|
/* or count, check rights, serialize data in a buffer */
|
|
}
|
|
|
|
atomic_t eventb_count = ATOMIC_INIT(0);
|
|
|
|
void probe_subsystem_eventb(void *probe_data, void *call_data,
|
|
const char *format, va_list *args)
|
|
{
|
|
/* Increment counter */
|
|
atomic_inc(&eventb_count);
|
|
}
|
|
|
|
static struct probe_data probe_array[] =
|
|
{
|
|
{ .name = "subsystem_event",
|
|
.format = "integer %d string %s",
|
|
.probe_func = probe_subsystem_event },
|
|
{ .name = "subsystem_eventb",
|
|
.format = MARK_NOARGS,
|
|
.probe_func = probe_subsystem_eventb },
|
|
};
|
|
|
|
static int __init probe_init(void)
|
|
{
|
|
int result;
|
|
int i;
|
|
|
|
for (i = 0; i < ARRAY_SIZE(probe_array); i++) {
|
|
result = marker_probe_register(probe_array[i].name,
|
|
probe_array[i].format,
|
|
probe_array[i].probe_func, &probe_array[i]);
|
|
if (result)
|
|
printk(KERN_INFO "Unable to register probe %s\n",
|
|
probe_array[i].name);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static void __exit probe_fini(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < ARRAY_SIZE(probe_array); i++)
|
|
marker_probe_unregister(probe_array[i].name,
|
|
probe_array[i].probe_func, &probe_array[i]);
|
|
printk(KERN_INFO "Number of event b : %u\n",
|
|
atomic_read(&eventb_count));
|
|
}
|
|
|
|
module_init(probe_init);
|
|
module_exit(probe_fini);
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Mathieu Desnoyers");
|
|
MODULE_DESCRIPTION("SUBSYSTEM Probe");
|