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Date: Wed, 25 Feb 2009 07:59:49 +0100
From: Frederic Weisbecker <fweisbec@...il.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
Andrew Morton <akpm@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Theodore Tso <tytso@....edu>,
Arjan van de Ven <arjan@...radead.org>,
Pekka Paalanen <pq@....fi>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Jason Baron <jbaron@...hat.com>,
Martin Bligh <mbligh@...gle.com>,
Mathieu Desnoyers <compudj@...stal.dyndns.org>,
"Frank Ch. Eigler" <fche@...hat.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Jens Axboe <jens.axboe@...cle.com>,
Masami Hiramatsu <mhiramat@...hat.com>,
Steven Rostedt <srostedt@...hat.com>
Subject: Re: [PATCH 4/4] tracing: make event directory structure
On Tue, Feb 24, 2009 at 09:56:12PM -0500, Steven Rostedt wrote:
> From: Steven Rostedt <srostedt@...hat.com>
>
> This patch adds the directory /debug/tracing/events/ that will contain
> all the registered trace points.
>
> # ls /debug/tracing/events/
> sched_kthread_stop sched_process_fork sched_switch
> sched_kthread_stop_ret sched_process_free sched_wait_task
> sched_migrate_task sched_process_wait sched_wakeup
> sched_process_exit sched_signal_send sched_wakeup_new
>
> # ls /debug/tracing/events/sched_switch/
> enable
>
> # cat /debug/tracing/events/sched_switch/enable
> 1
>
> # cat /debug/tracing/set_event
> sched_switch
Do you plan to add other things inside these events directory?
I mean, if you plan to only put an enable file on each of them,
it would be better to have just one file:
cat /debug/tracing/events/sched_switch
1
> Signed-off-by: Steven Rostedt <srostedt@...hat.com>
> ---
> kernel/trace/trace_events.c | 137 +++++++++++++++++++++++++++++++++++++++++--
> kernel/trace/trace_events.h | 7 ++-
> 2 files changed, 137 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 05bc80e..3bcb9df 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -12,6 +12,11 @@
>
> #include "trace_events.h"
>
> +#define events_for_each(event) \
> + for (event = __start_ftrace_events; \
> + (unsigned long)event < (unsigned long)__stop_ftrace_events; \
> + event++)
> +
The name for_each_events seems to me more intuitive, but it's just
a matter of taste.
Frederic.
> void event_trace_printk(unsigned long ip, const char *fmt, ...)
> {
> va_list ap;
> @@ -39,15 +44,16 @@ static void ftrace_clear_events(void)
>
> static int ftrace_set_clr_event(char *buf, int set)
> {
> - struct ftrace_event_call *call = (void *)__start_ftrace_events;
> + struct ftrace_event_call *call = __start_ftrace_events;
>
>
> - while ((unsigned long)call < (unsigned long)__stop_ftrace_events) {
> + events_for_each(call) {
>
> - if (strcmp(buf, call->name) != 0) {
> - call++;
> + if (!call->name)
> + continue;
> +
> + if (strcmp(buf, call->name) != 0)
> continue;
> - }
>
> if (set) {
> /* Already set? */
> @@ -223,6 +229,67 @@ ftrace_event_seq_open(struct inode *inode, struct file *file)
> return ret;
> }
>
> +static ssize_t
> +event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
> + loff_t *ppos)
> +{
> + struct ftrace_event_call *call = filp->private_data;
> + char *buf;
> +
> + if (call->enabled)
> + buf = "1\n";
> + else
> + buf = "0\n";
> +
> + return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
> +}
> +
> +static ssize_t
> +event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
> + loff_t *ppos)
> +{
> + struct ftrace_event_call *call = filp->private_data;
> + char buf[64];
> + unsigned long val;
> + int ret;
> +
> + if (cnt >= sizeof(buf))
> + return -EINVAL;
> +
> + if (copy_from_user(&buf, ubuf, cnt))
> + return -EFAULT;
> +
> + buf[cnt] = 0;
> +
> + ret = strict_strtoul(buf, 10, &val);
> + if (ret < 0)
> + return ret;
> +
> + switch (val) {
> + case 0:
> + if (!call->enabled)
> + break;
> +
> + call->enabled = 0;
> + call->unregfunc();
> + break;
> + case 1:
> + if (call->enabled)
> + break;
> +
> + call->enabled = 1;
> + call->regfunc();
> + break;
> +
> + default:
> + return -EINVAL;
> + }
> +
> + *ppos += cnt;
> +
> + return cnt;
> +}
> +
> static const struct seq_operations show_event_seq_ops = {
> .start = t_start,
> .next = t_next,
> @@ -252,10 +319,59 @@ static const struct file_operations ftrace_set_event_fops = {
> .release = seq_release,
> };
>
> +static const struct file_operations ftrace_enable_fops = {
> + .open = tracing_open_generic,
> + .read = event_enable_read,
> + .write = event_enable_write,
> +};
> +
> +static struct dentry *event_trace_events_dir(void)
> +{
> + static struct dentry *d_tracer;
> + static struct dentry *d_events;
> +
> + if (d_events)
> + return d_events;
> +
> + d_tracer = tracing_init_dentry();
> + if (!d_tracer)
> + return NULL;
> +
> + d_events = debugfs_create_dir("events", d_tracer);
> + if (!d_events)
> + pr_warning("Could not create debugfs "
> + "'events' directory\n");
> +
> + return d_events;
> +}
> +
> +static int
> +event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
> +{
> + struct dentry *entry;
> +
> + call->dir = debugfs_create_dir(call->name, d_events);
> + if (!call->dir) {
> + pr_warning("Could not create debugfs "
> + "'%s' directory\n", call->name);
> + return -1;
> + }
> +
> + entry = debugfs_create_file("enable", 0644, call->dir, call,
> + &ftrace_enable_fops);
> + if (!entry)
> + pr_warning("Could not create debugfs "
> + "'%s/enable' entry\n", call->name);
> +
> + return 0;
> +}
> +
> static __init int event_trace_init(void)
> {
> + struct ftrace_event_call *call = __start_ftrace_events;
> struct dentry *d_tracer;
> struct dentry *entry;
> + struct dentry *d_events;
>
> d_tracer = tracing_init_dentry();
> if (!d_tracer)
> @@ -275,6 +391,17 @@ static __init int event_trace_init(void)
> pr_warning("Could not create debugfs "
> "'set_event' entry\n");
>
> + d_events = event_trace_events_dir();
> + if (!d_events)
> + return 0;
> +
> + events_for_each(call) {
> + /* The linker may leave blanks */
> + if (!call->name)
> + continue;
> + event_create_dir(call, d_events);
> + }
> +
> return 0;
> }
> fs_initcall(event_trace_init);
> diff --git a/kernel/trace/trace_events.h b/kernel/trace/trace_events.h
> index 39342f8..cb8455b 100644
> --- a/kernel/trace/trace_events.h
> +++ b/kernel/trace/trace_events.h
> @@ -1,11 +1,13 @@
> #ifndef _LINUX_KERNEL_TRACE_EVENTS_H
> #define _LINUX_KERNEL_TRACE_EVENTS_H
>
> +#include <linux/debugfs.h>
> #include <linux/ftrace.h>
> #include "trace.h"
>
> struct ftrace_event_call {
> char *name;
> + struct dentry *dir;
> int enabled;
> int (*regfunc)(void);
> void (*unregfunc)(void);
> @@ -39,6 +41,7 @@ static void ftrace_unreg_event_##call(void) \
> } \
> \
> static struct ftrace_event_call __used \
> +__attribute__((__aligned__(4))) \
> __attribute__((section("_ftrace_events"))) event_##call = { \
> .name = #call, \
> .regfunc = ftrace_reg_event_##call, \
> @@ -46,7 +49,7 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
> }
>
> void event_trace_printk(unsigned long ip, const char *fmt, ...);
> -extern unsigned long __start_ftrace_events[];
> -extern unsigned long __stop_ftrace_events[];
> +extern struct ftrace_event_call __start_ftrace_events[];
> +extern struct ftrace_event_call __stop_ftrace_events[];
>
> #endif /* _LINUX_KERNEL_TRACE_EVENTS_H */
> --
> 1.5.6.5
>
> --
--
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