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Linux Kernel Markers: support multiple probes

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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>
This commit is contained in:
Mathieu Desnoyers
2008-02-13 15:03:37 -08:00
committed by Linus Torvalds
parent 9170d2f6e1
commit fb40bd78b0
6 changed files with 579 additions and 250 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
arch/powerpc/platforms/cell/spufs/sputrace.c
View File

@ -146,34 +146,28 @@ static void sputrace_log_item(const char *name, struct spu_context *ctx,
wake_up(&sputrace_wait);
}
static void spu_context_event(const struct marker *mdata,
void *private, const char *format, ...)
static void spu_context_event(void *probe_private, void *call_data,
const char *format, va_list *args)
{
struct spu_probe *p = mdata->private;
va_list ap;
struct spu_probe *p = probe_private;
struct spu_context *ctx;
struct spu *spu;
va_start(ap, format);
ctx = va_arg(ap, struct spu_context *);
spu = va_arg(ap, struct spu *);
ctx = va_arg(*args, struct spu_context *);
spu = va_arg(*args, struct spu *);
sputrace_log_item(p->name, ctx, spu);
va_end(ap);
}
static void spu_context_nospu_event(const struct marker *mdata,
void *private, const char *format, ...)
static void spu_context_nospu_event(void *probe_private, void *call_data,
const char *format, va_list *args)
{
struct spu_probe *p = mdata->private;
va_list ap;
struct spu_probe *p = probe_private;
struct spu_context *ctx;
va_start(ap, format);
ctx = va_arg(ap, struct spu_context *);
ctx = va_arg(*args, struct spu_context *);
sputrace_log_item(p->name, ctx, NULL);
va_end(ap);
}
struct spu_probe spu_probes[] = {
@ -219,10 +213,6 @@ static int __init sputrace_init(void)
if (error)
printk(KERN_INFO "Unable to register probe %s\n",
p->name);
error = marker_arm(p->name);
if (error)
printk(KERN_INFO "Unable to arm probe %s\n", p->name);
}
return 0;
@ -238,7 +228,8 @@ static void __exit sputrace_exit(void)
int i;
for (i = 0; i < ARRAY_SIZE(spu_probes); i++)
marker_probe_unregister(spu_probes[i].name);
marker_probe_unregister(spu_probes[i].name,
spu_probes[i].probe_func, &spu_probes[i]);
remove_proc_entry("sputrace", NULL);
kfree(sputrace_log);