From: Frederic Weisbecker <fweisbec@gmail.com>
To: Li Zefan <lizf@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
Tom Zanussi <tzanussi@gmail.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] tracing/events: make struct trace_entry->type to be int type
Date: Wed, 22 Apr 2009 11:10:46 +0200 [thread overview]
Message-ID: <20090422091045.GA6031@nowhere> (raw)
In-Reply-To: <49EEDB0E.5070207@cn.fujitsu.com>
On Wed, Apr 22, 2009 at 04:53:34PM +0800, Li Zefan wrote:
> struct trace_entry->type is unsigned char, while trace event's id is
> int type, thus for a event with id >= 256, it's entry->type is cast
> to (id % 256), and then we can't see the trace output of this event.
>
> # insmod trace-events-sample.ko
> # echo foo_bar > /mnt/tracing/set_event
> # cat /debug/tracing/events/trace-events-sample/foo_bar/id
> 256
> # cat /mnt/tracing/trace_pipe
> <...>-3548 [001] 215.091142: Unknown type 0
> <...>-3548 [001] 216.089207: Unknown type 0
> <...>-3548 [001] 217.087271: Unknown type 0
> <...>-3548 [001] 218.085332: Unknown type 0
>
> [ Impact: fix output for trace events with id >= 256 ]
>
> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Indeed, now with the trace_events, we are approaching this possible
overflow and the type is indeed an int:
struct trace_event *ftrace_find_event(int type)
Curious: does it only happen with the trace-event-sample?
I doubt we already reached this threshold of event number.
But anyway, it's a good thing.
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
> ---
> include/linux/ftrace_event.h | 4 ++--
> include/trace/ftrace.h | 2 +-
> kernel/trace/trace.c | 4 ++--
> kernel/trace/trace.h | 2 +-
> kernel/trace/trace_events.c | 2 +-
> 5 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
> index 75f3ac0..2a4a407 100644
> --- a/include/linux/ftrace_event.h
> +++ b/include/linux/ftrace_event.h
> @@ -16,7 +16,7 @@ struct dentry;
> * bash-15816 [01] 235.197585: idle_cpu <- irq_enter
> */
> struct trace_entry {
> - unsigned char type;
> + int type;
> unsigned char flags;
> unsigned char preempt_count;
> int pid;
> @@ -73,7 +73,7 @@ enum print_line_t {
>
>
> struct ring_buffer_event *
> -trace_current_buffer_lock_reserve(unsigned char type, unsigned long len,
> +trace_current_buffer_lock_reserve(int type, unsigned long len,
> unsigned long flags, int pc);
> void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
> unsigned long flags, int pc);
> diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
> index 39a3351..15ef08d 100644
> --- a/include/trace/ftrace.h
> +++ b/include/trace/ftrace.h
> @@ -198,7 +198,7 @@ ftrace_define_fields_##call(void) \
> struct ftrace_event_call *event_call = &event_##call; \
> int ret; \
> \
> - __common_field(unsigned char, type); \
> + __common_field(int, type); \
> __common_field(unsigned char, flags); \
> __common_field(unsigned char, preempt_count); \
> __common_field(int, pid); \
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index b9a3adc..b6183bc 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -838,7 +838,7 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
> }
>
> struct ring_buffer_event *trace_buffer_lock_reserve(struct trace_array *tr,
> - unsigned char type,
> + int type,
> unsigned long len,
> unsigned long flags, int pc)
> {
> @@ -881,7 +881,7 @@ void trace_buffer_unlock_commit(struct trace_array *tr,
> }
>
> struct ring_buffer_event *
> -trace_current_buffer_lock_reserve(unsigned char type, unsigned long len,
> +trace_current_buffer_lock_reserve(int type, unsigned long len,
> unsigned long flags, int pc)
> {
> return trace_buffer_lock_reserve(&global_trace,
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 8750e83..3e5c664 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -422,7 +422,7 @@ void init_tracer_sysprof_debugfs(struct dentry *d_tracer);
> struct ring_buffer_event;
>
> struct ring_buffer_event *trace_buffer_lock_reserve(struct trace_array *tr,
> - unsigned char type,
> + int type,
> unsigned long len,
> unsigned long flags,
> int pc);
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 9631caf..86fa720 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -398,7 +398,7 @@ static int trace_write_header(struct trace_seq *s)
> "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
> "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
> "\n",
> - FIELD(unsigned char, type),
> + FIELD(int, type),
> FIELD(unsigned char, flags),
> FIELD(unsigned char, preempt_count),
> FIELD(int, pid),
> --
> 1.5.4.rc3
>
next prev parent reply other threads:[~2009-04-22 9:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-22 8:53 [PATCH] tracing/events: make struct trace_entry->type to be int type Li Zefan
2009-04-22 9:10 ` Frederic Weisbecker [this message]
2009-04-22 9:19 ` Li Zefan
2009-04-22 9:40 ` Ingo Molnar
2009-04-22 10:06 ` [tip:tracing/core] " tip-bot for Li Zefan
2009-04-22 13:40 ` Steven Rostedt
2009-04-22 13:52 ` Ingo Molnar
2009-04-22 14:07 ` Steven Rostedt
2009-04-23 0:57 ` Li Zefan
2009-04-22 13:15 ` [PATCH] " Steven Rostedt
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