From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: rostedt@goodmis.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 10/11] tracing: add and use generic set_trigger_filter() implementation
Date: Fri, 21 Jun 2013 13:18:05 +0900 [thread overview]
Message-ID: <51C3D3FD.2070408@hitachi.com> (raw)
In-Reply-To: <8fe2c1ceb63a6375b56f046de835742f18b955ce.1371751701.git.tom.zanussi@linux.intel.com>
(2013/06/21 3:31), Tom Zanussi wrote:
> diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
> index 88ac7da..7c5627f 100644
> --- a/include/trace/ftrace.h
> +++ b/include/trace/ftrace.h
> @@ -522,14 +522,6 @@ ftrace_raw_event_##call(void *__data, proto) \
> int __data_size; \
> int pc; \
> \
> - if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT, \
> - &ftrace_file->flags)) \
> - event_triggers_call(ftrace_file); \
> - \
> - if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, \
> - &ftrace_file->flags)) \
> - return; \
> - \
> local_save_flags(irq_flags); \
> pc = preempt_count(); \
> \
> @@ -547,8 +539,22 @@ ftrace_raw_event_##call(void *__data, proto) \
> \
> { assign; } \
> \
> + if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, \
> + &ftrace_file->flags)) { \
> + ring_buffer_discard_commit(buffer, event); \
> + \
> + if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT, \
> + &ftrace_file->flags)) \
> + event_triggers_call(ftrace_file, entry); \
> + return; \
> + } \
> + \
> if (!filter_current_check_discard(buffer, event_call, entry, event)) \
> trace_buffer_unlock_commit(buffer, event, irq_flags, pc); \
> + \
> + if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT, \
> + &ftrace_file->flags)) \
> + event_triggers_call(ftrace_file, entry); \
Actually, since "entry" is a part of "event" which may be already discarded,
I think we should not access it here. It may not cause real problem because
even if it is discarded, that does NOT mean it is freed. However, it depends
on the ring-buffer implementation.
I recommend you to call event triggers before commit the event. It will also
make the code simpler :)
> diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
> index e287011..47fa712 100644
> --- a/kernel/trace/trace_syscalls.c
> +++ b/kernel/trace/trace_syscalls.c
> @@ -319,14 +319,6 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
> if (!sys_data)
> return;
>
> - if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT,
> - &sys_data->enter_file->flags))
> - event_triggers_call(sys_data->enter_file);
> -
> - if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT,
> - &sys_data->enter_file->flags))
> - return;
> -
> size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
>
> buffer = tr->trace_buffer.buffer;
> @@ -339,9 +331,23 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
> entry->nr = syscall_nr;
> syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
>
> + if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT,
> + &sys_data->enter_file->flags)) {
> + ring_buffer_discard_commit(buffer, event);
> +
> + if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT,
> + &sys_data->enter_file->flags))
> + event_triggers_call(sys_data->enter_file, entry);
> + return;
> + }
> +
> if (!filter_current_check_discard(buffer, sys_data->enter_event,
> entry, event))
> trace_current_buffer_unlock_commit(buffer, event, 0, 0);
> +
> + if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT,
> + &sys_data->enter_file->flags))
> + event_triggers_call(sys_data->enter_file, entry);
> }
>
> static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
> @@ -363,14 +369,6 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
> if (!sys_data)
> return;
>
> - if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT,
> - &sys_data->exit_file->flags))
> - event_triggers_call(sys_data->exit_file);
> -
> - if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT,
> - &sys_data->exit_file->flags))
> - return;
> -
> buffer = tr->trace_buffer.buffer;
> event = trace_buffer_lock_reserve(buffer,
> sys_data->exit_event->event.type, sizeof(*entry), 0, 0);
> @@ -381,9 +379,23 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
> entry->nr = syscall_nr;
> entry->ret = syscall_get_return_value(current, regs);
>
> + if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT,
> + &sys_data->exit_file->flags)) {
> + ring_buffer_discard_commit(buffer, event);
> +
> + if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT,
> + &sys_data->exit_file->flags))
> + event_triggers_call(sys_data->exit_file, entry);
> + return;
> + }
> +
> if (!filter_current_check_discard(buffer, sys_data->exit_event,
> entry, event))
> trace_current_buffer_unlock_commit(buffer, event, 0, 0);
> +
> + if (test_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT,
> + &sys_data->exit_file->flags))
> + event_triggers_call(sys_data->exit_file, entry);
> }
>
> static int reg_event_syscall_enter(struct ftrace_event_file *file,
>
Same changes are needed here.
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
next prev parent reply other threads:[~2013-06-21 4:18 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-20 18:31 [PATCH 00/11] tracing: trace event triggers Tom Zanussi
2013-06-20 18:31 ` [PATCH 01/11] tracing: simplify event_enable_read() Tom Zanussi
2013-06-21 6:52 ` Masami Hiramatsu
2013-06-20 18:31 ` [PATCH 02/11] tracing: add missing syscall_metadata comment Tom Zanussi
2013-06-21 7:06 ` Masami Hiramatsu
2013-06-21 19:48 ` Steven Rostedt
2013-06-20 18:31 ` [PATCH 03/11] tracing: add soft disable for syscall events Tom Zanussi
2013-06-21 6:53 ` zhangwei(Jovi)
2013-06-21 20:22 ` Steven Rostedt
2013-06-22 5:08 ` Jovi Zhang
2013-06-22 11:45 ` Steven Rostedt
2013-06-20 18:31 ` [PATCH 04/11] tracing: fix disabling of soft disable Tom Zanussi
2013-06-21 11:12 ` Masami Hiramatsu
2013-06-21 20:39 ` Steven Rostedt
2013-06-21 21:14 ` Tom Zanussi
2013-06-22 5:25 ` Tom Zanussi
2013-07-01 11:38 ` Masami Hiramatsu
2013-06-20 18:31 ` [PATCH 05/11] tracing: add basic event trigger framework Tom Zanussi
2013-06-21 12:12 ` Masami Hiramatsu
2013-06-20 18:31 ` [PATCH 06/11] tracing: add 'traceon' and 'traceoff' event trigger commands Tom Zanussi
2013-06-20 18:31 ` [PATCH 07/11] tracing: add 'snapshot' event trigger command Tom Zanussi
2013-06-20 18:31 ` [PATCH 08/11] tracing: add 'stacktrace' " Tom Zanussi
2013-06-20 18:31 ` [PATCH 09/11] tracing: add 'enable_event' and 'disable_event' event trigger commands Tom Zanussi
2013-06-20 18:31 ` [PATCH 10/11] tracing: add and use generic set_trigger_filter() implementation Tom Zanussi
2013-06-21 4:18 ` Masami Hiramatsu [this message]
2013-06-21 17:59 ` Tom Zanussi
2013-06-22 11:53 ` Steven Rostedt
2013-06-20 18:31 ` [PATCH 11/11] tracing: add documentation for trace event triggers Tom Zanussi
2013-06-21 19:45 ` [PATCH 00/11] tracing: " Steven Rostedt
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